Patent Publication Number: US-2023142099-A1

Title: Cd8 binding agents

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of and priority to U.S. Provisional Patent Application No. 62/542,920, filed Aug. 9, 2017, the content of which is hereby incorporated by reference in its entirety. 
    
    
     FIELD 
     The present invention relates, in part, to binding agents (e.g., antibodies, such as, without limitation, VHHs) which bind CD8 and their use as therapeutic and diagnostic agents. 
     DESCRIPTION OF THE TEXT FILE SUBMITTED ELECTRONICALLY 
     The contents of the text file submitted electronically herewith are incorporated herein by reference in their entirety: A computer readable format copy of the Sequence Listing (filename: ORN-032PC_ST25, date created: Aug. 8, 2018; file size: 828 KB). 
     BACKGROUND 
     Activated CD8+T lymphocytes (also known as cytotoxic T cells or CTLs) represent the main line of defense against a wide gamut of microbial pathogens. Further still, CTLs also play an important role in antitumor immunity. Specifically, these effector cells can curb cancer development through mechanisms including production of interferon (IFN)-γ and cytotoxins, exocytosis of lytic proteins (e.g., perforin, granzymes), and receptor-ligand binding of FAS molecules. 
     Nevertheless, microbial pathogens and tumor cells have developed various mechanisms to escape immune destruction by CTLs. For example, tumors can evade immune surveillance by crippling CTL functionality via, for instance, production of immune suppressive cytokines and engagement of immune checkpoint inhibition, either by the cancer cells themselves or by non-cancerous cells present in the tumor microenvironment. Cancer cells have also been shown to delete CTLs through apoptosis. 
     Accordingly, there remains a need for improved immunotherapeutic agents, including, for example, those that can effectively derail tumor evasion and enhance anti-tumor immunity as mediated, for example, by CTLs. 
     SUMMARY 
     In various aspects, the present invention relates to CD8 binding agents having at least one targeting moiety that specifically binds to CD8. In various embodiments, these CD8 binding agents bind to, but do not functionally modulate (including, without limitation, partially or fully neutralizing) CD8. Therefore, in various embodiments, the present CD8 binding agents have use in, for instance, recruiting a CD8-expressing cell to a site of interest while still allowing the CD8-expressing cell to signal via CD8 (i.e. the binding of the CD8 binding agent does not reduce or eliminate CD8 signaling at the site of interest). In an embodiment, the targeting moiety is a single domain antibody (VHH). In various embodiments, the CD8 binding agent further comprises a signaling agent, e.g., without limitation, an interferon, an interleukin, and a tumor necrosis factor, that may be modified to attenuate activity. In various embodiments, the CD8 binding agent comprises additional targeting moieties that bind to other antigens of interest. In an embodiment, the other antigens of interest are present on tumor cells. In another embodiment, the other antigens of interest are present on immune cells. In these embodiments, the present CD8 binding agent may directly or indirectly recruit an immune cell, e.g. an immune cell that can kill and/or suppress a tumor cell (e.g., cytotoxic T cells), to a site of action (such as, by way of non-limiting example, the tumor microenvironment). 
     In various embodiments, the present CD8 binding agents find use in the treatment of various diseases or disorders such as cancer, infections, immune disorders, autoimmune diseases, and other diseases and disorders, and the present invention encompasses various methods of treatment. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    depicts the nucleotide sequence of 69 different VHHs specific for human CD8. Gaps were introduced in order to align sequences. 
         FIG.  2    shows the amino acid sequences of 69 different VHHs specific for human CD8. Complementarity determining regions (CDR1, CDR2 and CDR3) as indicated are defined according to Kabat. Gaps were introduced in order to align sequences. The above 69 different VHHs belong to 31 different CDR3 groups (see  FIG.  3   ). VHHs belonging to the same group are very similar and their amino acid sequences suggest that they are from clonally-related B-cells resulting from somatic hypermutation or from the same B-cell but diversified due to RT and/or PCR error during library construction. VHHs belonging to the same group recognize the same epitope but their other characteristics (e.g. affinity, potency, stability, expression yield, etc.) can be different. 
         FIG.  3    provides a table depicting that the 69 different VHHs belonged to 31 different CDR3 groups. 
         FIG.  4    shows the binding of various VHHs to Hek293 T cells transfected with human CD8. 
         FIGS.  5 A-B  shows pSTAT1 signaling assay in CD8 positive ( FIG.  5 A ) and CD8 negative cells ( FIG.  5 B ). Chimeras studied were anti-human CD8 VHH/human IFN R149A (i.e., CD8 VHH-AFN). Peripheral blood mononuclear cells (PBMCs) from healthy donors were stained with CD8 antibody and stimulated with CD8 VHH-AFN&#39;s for 15 minutes. After fixation and permeabilisation, cells were stained with a pSTAT1 antibody. Data are plotted as percentage of pSTAT1 positive cells. 
         FIGS.  6 A-F  are graphs showing CD8 VHH AcTaferons (AFNs) stimulation of STAT phosphorylation in PBMC&#39;s from healthy donors. PBMC&#39;s from healthy donors were stained with CD8 Ab and stimulated with wild type IFNα2 ( FIG.  6 A ) or CD8 VHH AFN&#39;s (i.e., AFN 2CDA5 ( FIG.  6 B ), AFN 3CDA19 ( FIG.  6 C ), AFN 1CDA65 ( FIG.  6 D ), AFN 2CDA74 (C50S) ( FIG.  6 E ), or AFN 2CDA68 ( FIG.  6 F )) for 15 minutes. After fixation and permeabilization, cells were stained with a pSTAT1 Ab. The data is plotted as increase over baseline STAT1 phosphorylation. 
         FIGS.  7 A-E  are graphs showing that CD8 VHHs (i.e., 2CDA5 ( FIG.  7 A ), 3CDA19 ( FIG.  7 B ), 1CDA65 ( FIG.  7 C ), 2CDA74 (C50S) ( FIG.  7 D ), and 2CDA68 ( FIG.  7 E )) bind equally as well to human and cynomolgus CD8 alpha in FACs. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention is based, in part, on the discovery of agents (e.g. antibodies such as, by way of non-limiting example, VHHs) that recognize and bind to CD8. In various embodiments, these CD8 binding agents bind to, but do not functionally modulate CD8. In various embodiments, these CD8 binding agents may bind to and directly or indirectly recruit immune cells to sites in need of therapeutic action (e.g. a tumor). The present invention further provides pharmaceutical compositions comprising the CD8 binding agents and their use in the treatment of various diseases. 
     CD8 Binding Agents 
     In various embodiments, the present CD8 binding agent is a protein-based agent capable of specific binding to CD8. In various embodiments, the present CD8 binding agent is a protein-based agent capable of specific binding to CD8 without functionally modulating (e.g. partial or complete neutralization) CD8. 
     CD8 is a heterodimeric type I transmembrane glycoprotein, whose α and β chains are both comprised of an immunoglobulin (Ig)-like extracellular domain connected by an extended O-glycosylated stalk to a single-pass transmembrane domain and a short cytoplasmic tail (Li et al., 2013). The cytoplasmic region of the CD8 α-chain contains two cysteine motifs that serve as a docking site for src tyrosine kinase p56lck (Lck). In contrast, this Lck binding domain appears to be absent from the CD8 β chain, suggesting that the β chain is not involved in downstream signaling (Artyomov et al., 2010). CD8 functions as a co-receptor for the T-cell receptor with its principle role being the recruitment of Lck to the TCR-pMHC complex following co-receptor binding to MHC (Turner et al., 1990, Veillette et al., 1988). The increase in the local concentration of this kinase activates a signaling cascade that recruits and activates ζ-chain-associated protein kinase 70 (ZAP-70), subsequently leading to the amplification of T-cell activation signals (Purbhoo et al., 2001, Laugel et al., 2007a). 
     In various embodiments, the CD8 binding agent of the invention comprises a targeting moiety having an antigen recognition domain that recognizes an epitope present on the CD8 α and/or β chains. In an embodiment, the antigen-recognition domain recognizes one or more linear epitopes on the CD8 α and/or β chains. As used herein, a linear epitope refers to any continuous sequence of amino acids present on the CD8 α and/or β chains. In another embodiment, the antigen-recognition domain recognizes one or more conformational epitopes present on the CD8 α and/or β chains. As used herein, a conformation epitope refers to one or more sections of amino acids (which may be discontinuous) which form a three-dimensional surface with features and/or shapes and/or tertiary structures capable of being recognized by an antigen recognition domain. 
     In various embodiments, the CD8 binding agent of the present invention may bind to the full-length and/or mature forms and/or isoforms and/or splice variants and/or fragments and/or any other naturally occurring or synthetic analogs, variants, or mutants of human CD8 α and/or β chains. In various embodiments, the CD8 binding agent of the invention may bind to any forms of the human CD8 α and/or β chains, including monomeric, dimeric, heterodimeric, multimeric and associated forms. In an embodiment, the CD8 binding agent binds to the monomeric form of CD8 α chain or CD8 β chain. In another embodiment, the CD8 binding agent binds to a homodimeric form comprised of two CD8 α chains or two CD8 β chains. In a further embodiment, the CD8 binding agent binds to a heterodimeric form comprised of one CD8 α chain and one CD8 β chain. 
     In an embodiment, the present CD8 binding agent comprises a targeting moiety with an antigen recognition domain that recognizes one or more epitopes present on the human CD8 α chain. In an embodiment, the human CD8α chain comprises the amino acid sequence of Isoform 1 (SEQ ID NO:1). 
     In an embodiment, the human CD8 α chain comprises the amino acid sequence of Isoform 2 (SEQ ID NO:2). 
     In an embodiment, the human CD8 α chain comprises the amino acid sequence of Isoform 3 (SEQ ID NO:3). 
     In an embodiment, the present CD8 binding agent comprises a targeting moiety with an antigen recognition domain that recognizes one or more epitopes present on the human CD8 β chain. In an embodiment, the human CD8 β chain comprises the amino acid sequence of Isoform 1 (SEQ ID NO:4). 
     In an embodiment, the human CD8 β chain comprises the amino acid sequence of Isoform 2 (SEQ ID NO:5). 
     In an embodiment, the human CD8 β chain comprises the amino acid sequence of Isoform 3 (SEQ ID NO:6). 
     In an embodiment, the human CD8 β chain comprises the amino acid sequence of Isoform 4 (SEQ ID NO:7). 
     In an embodiment, the human CD8 β chain comprises the amino acid sequence of Isoform 5 (SEQ ID NO:8). 
     In an embodiment, the human CD8 β chain comprises the amino acid sequence of Isoform 6 (SEQ ID NO:9). 
     In an embodiment, the human CD8 β chain comprises the amino acid sequence of Isoform 7 (SEQ ID NO:10). 
     In an embodiment, the human CD8 β chain comprises the amino acid sequence of Isoform 8 (SEQ ID NO:11). 
     In various embodiments, the present CD8 binding agent comprises a targeting moiety capable of specific binding. 
     In various embodiments, the CD8 binding agent comprises a targeting moiety having an antigen recognition domain such as an antibody or derivatives thereof. In an embodiment, the CD8 binding agent comprises a targeting moiety which is an antibody. In various embodiments, the antibody is a full-length multimeric protein that includes two heavy chains and two light chains. Each heavy chain includes one variable region (e.g., V H ) and at least three constant regions (e.g., CH 1 , CH 2  and CH 3 ), and each light chain includes one variable region (V L ) and one constant region (C L ). The variable regions determine the specificity of the antibody. Each variable region comprises three hypervariable regions also known as complementarity determining regions (CDRs) flanked by four relatively conserved framework regions (FRs). The three CDRs, referred to as CDR1, CDR2, and CDR3, contribute to the antibody binding specificity. In some embodiments, the antibody is a chimeric antibody. In some embodiments, the antibody is a humanized antibody. 
     In some embodiments, the CD8 binding agent comprises a targeting moiety which is an antibody derivative or format. In some embodiments, the present CD8 binding agent comprises a targeting moiety which is a single-domain antibody, a recombinant heavy-chain-only antibody (VHH), a single-chain antibody (scFv), a shark heavy-chain-only antibody (VNAR), a microprotein (cysteine knot protein, knottin), a DARPin; a Tetranectin; an Affibody; a Transbody; an Anticalin; an AdNectin; an Affilin; an Affimer, a Microbody; an aptamer; an alterase; a plastic antibody; a phylomer; a stradobody; a maxibody; an evibody; a fynomer, an armadillo repeat protein, a Kunitz domain, an avimer, an atrimer, a probody, an immunobody, a triomab, a troybody; a pepbody; a vaccibody, a UniBody; a DuoBody, a Fv, a Fab, a Fab′, a F(ab′) 2 , a peptide mimetic molecule, or a synthetic molecule, as described in US Patent Nos. or Patent Publication Nos. U.S. Pat. No. 7,417,130, US 2004/132094, U.S. Pat. No. 5,831,012, US 2004/023334, U.S. Pat. Nos. 7,250,297, 6,818,418, US 2004/209243, U.S. Pat. Nos. 7,838,629, 7,186,524, 6,004,746, 5,475,096, US 2004/146938, US 2004/157209, U.S. Pat. Nos. 6,994,982, 6,794,144, US 2010/239633, U.S. Pat. No. 7,803,907, US 2010/119446, and/or U.S. Pat. No. 7,166,697, the contents of which are hereby incorporated by reference in their entireties. See also, Storz MAbs. 2011 May-June; 3(3): 310-317. 
     In some embodiments, the CD8 binding agent comprises a targeting moiety which is a single-domain antibody, such as a VHH. The VHH may be derived from, for example, an organism that produces VHH antibody such as a camelid, a shark, or the VHH may be a designed VHH. VHHs are antibody-derived therapeutic proteins that contain the unique structural and functional properties of naturally-occurring heavy-chain antibodies. VHH technology is based on fully functional antibodies from camelids that lack light chains. These heavy-chain antibodies contain a single variable domain (V H H) and two constant domains (CH2 and CH3). 
     In an embodiment, the CD8 binding agent comprises a VHH. In some embodiments, the VHH is a humanized VHH or camelized VHH. 
     In some embodiments, the VHH comprises a fully human V H  domain, e.g. a HUMABODY (Crescendo Biologics, Cambridge, UK). In some embodiments, fully human V H  domain, e.g. a HUMABODY is monovalent, bivalent, or trivalent. In some embodiments, the fully human V H  domain, e.g. a HUMABODY is mono- or multi-specific such as monospecific, bispecific, or trispecific. Illustrative fully human V H  domains, e.g. a HUMABODIES are described in, for example, WO2016/113555 and WO2016/113557, the entire disclosure of which is incorporated by reference. 
     In some embodiments, the CD8 binding agent comprises a targeting moiety which is a VHH comprising a single amino acid chain having four “framework regions” or FRs and three “complementary determining regions” or CDRs. As used herein, “framework region” or “FR” refers to a region in the variable domain which is located between the CDRs. As used herein, “complementary determining region” or “CDR” refers to variable regions in VHHs that contains the amino acid sequences capable of specifically binding to antigenic targets. 
     In various embodiments, the CD8 binding agent comprises a VHH having a variable domain comprising at least one CDR1, CDR2, and/or CDR3 sequences. 
     In some embodiments, the CDR1 sequence is selected from: 
     
       
         
           
               
               
            
               
                   
                 (SEQ ID NO: 12) 
               
               
                   
                 GRSFSSYTLA;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 13) 
               
               
                   
                 GRTFSSYTMG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 14) 
               
               
                   
                 GRTFSSYIMG; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 15) 
               
               
                   
                 GRTFSSYTMG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 16) 
               
               
                   
                 GRTSGRTFSSYTMG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 17) 
               
               
                   
                 GRTFSSYAMG; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 18) 
               
               
                   
                 GLTFSNYIMG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 19) 
               
               
                   
                 GRTFSSYTMG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 20) 
               
               
                   
                 GRTFSSDTMG; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 21) 
               
               
                   
                 GLTFSNYIMG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 22) 
               
               
                   
                 GFTLDYYGIG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 23) 
               
               
                   
                 GHTFSSYTMG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 24) 
               
               
                   
                 GRTFSSYVIG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 25) 
               
               
                   
                 GFAFDGYAIG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 26) 
               
               
                   
                 GFAFGFFDMT;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 27) 
               
               
                   
                 GRTFSNYVIG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 28) 
               
               
                   
                 GSIFSINVMG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 29) 
               
               
                   
                 GRTFSNYNVG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 30) 
               
               
                   
                 GHTFSSYTMG; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 31) 
               
               
                   
                 GRTFSTYPVG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 32) 
               
               
                   
                 GRTFSNYAMG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 33) 
               
               
                   
                 GRTFSDYRMG; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 34) 
               
               
                   
                 GLTFSNYIMA;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 35) 
               
               
                   
                 GRTFSNSVMG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 36) 
               
               
                   
                 GRTFSSYIIG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 37) 
               
               
                   
                 GRTFSSYVMG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 38) 
               
               
                   
                 GGTFSNYVMG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 39) 
               
               
                   
                 GRTFSNYGIG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 40) 
               
               
                   
                 GFTFDDYAIA;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 41) 
               
               
                   
                 GRTFSSYTVA;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 42) 
               
               
                   
                 GFPFDDYAIA;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 43) 
               
               
                   
                 GRTFSSYVMG; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 44) 
               
               
                   
                 GRTLSSNPMA;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 45) 
               
               
                   
                 GFTFDNYAIG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 46) 
               
               
                   
                 GRAFSSYFMG; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 47) 
               
               
                   
                 TPTFSSYNMG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 48) 
               
               
                   
                 GFTFDDYAIA;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 49) 
               
               
                   
                 GGTFSGYIMG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 50) 
               
               
                   
                 GRSFSSYTIA;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 51) 
               
               
                   
                 GFSSDDYTIG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 52) 
               
               
                   
                 GFTFDDYTIG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 53) 
               
               
                   
                 GFSSDDYTIG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 54) 
               
               
                   
                 GFTFDQYTIA;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 55) 
               
               
                   
                 GRTFSSYAMA;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 56) 
               
               
                   
                 GFAFDGYAIG; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 57) 
               
               
                   
                 GFSSDDYTIA;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 58) 
               
               
                   
                 GFSSDDYTIG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 59) 
               
               
                   
                 GFTFDDYTIG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 60) 
               
               
                   
                 GFSSDDYTIG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 61) 
               
               
                   
                 GFSSDDYTIG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 62) 
               
               
                   
                 GFSFDDYAIA;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 63) 
               
               
                   
                 GFSSDDYTIG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 64) 
               
               
                   
                 GFTGNDLAIG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 65) 
               
               
                   
                 GFSSDDYTIA;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 66) 
               
               
                   
                 EGTLSSYGIG; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 67) 
               
               
                   
                 GFSSDDYTIA;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 68) 
               
               
                   
                 GFTFDDYAIA;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 69) 
               
               
                   
                 GLSSDDYTIG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 70) 
               
               
                   
                 GLSSDDYTIG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 71) 
               
               
                   
                 GFSSDDYTIG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 73) 
               
               
                   
                 GFTFDDYAIA; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 72)  
               
               
                   
                 GFSFDDYTIG; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 74) 
               
               
                   
                 GFTFDDYAIG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 75) 
               
               
                   
                 GFTFGDYTIG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 76)  
               
               
                   
                 EGTFSSYGIG; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 77) 
               
               
                   
                 GFSSDDYTIG; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 78) 
               
               
                   
                 GVSIGDYNIG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 79) 
               
               
                   
                 GFTFDDYTIA; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 80) 
               
               
                   
                 GFTFDDYTIA. 
               
            
           
         
       
     
     In some embodiments, the CDR2 sequence is selected from: 
     
       
         
           
               
               
            
               
                   
                 (SEQ ID NO: 81) 
               
               
                   
                 ASITWGGGNTY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 82) 
               
               
                   
                 AATVWTGAGTV;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 83) 
               
               
                   
                 AAIGWSADITV; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 84) 
               
               
                   
                 AFIDWSGGGTY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 85) 
               
               
                   
                 ATITWGGGSTY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 86) 
               
               
                   
                 AAISWSGGPTV; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 87) 
               
               
                   
                 AAITWGGGSTV;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 88) 
               
               
                   
                 AAITWSGVSTV;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 89) 
               
               
                   
                 GAIMWSGAFTH; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 90) 
               
               
                   
                 AAITWGGGSTV;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 91) 
               
               
                   
                 SCISSSDRNTY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 92) 
               
               
                   
                 AFIDWSGGGTY; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 93) 
               
               
                   
                 AVITWSGDSTY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 94) 
               
               
                   
                 ACISSKDGSTY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 95) 
               
               
                   
                 SGINSIGGSTT; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 96) 
               
               
                   
                 AVVTWSGDSTY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 97) 
               
               
                   
                 AKITNFGITS;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 98) 
               
               
                   
                 SFISWISDITY; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 99) 
               
               
                   
                 AFIDWSGGGTY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NQ: 100) 
               
               
                   
                 AVILWSGVSTY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 101) 
               
               
                   
                 AAIVWSGGSTY; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 102) 
               
               
                   
                 AAISSSGYHTY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 103) 
               
               
                   
                 SCISSPDGSTY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 104) 
               
               
                   
                 AAVLWSGVSTA; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 105) 
               
               
                   
                 VAITWDGSATT;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 106) 
               
               
                   
                 AAIGWNGGITY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 107) 
               
               
                   
                 GFITWSGASTY; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NQ: 108) 
               
               
                   
                 AGINWSGESAD;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 109) 
               
               
                   
                 SCIERSDGSTY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 110) 
               
               
                   
                 SCISNTDSSTY; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 111) 
               
               
                   
                 SCISNTDSSTY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 112) 
               
               
                   
                 AQISWSAGSIY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 113) 
               
               
                   
                 AGMSWNPGPAV; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 114) 
               
               
                   
                 SCISRSDGSTY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 115) 
               
               
                   
                 ANIGWTGDMTY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 116) 
               
               
                   
                 AAIIWSGSMTY; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 117) 
               
               
                   
                 SCISNTDSSTY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 118) 
               
               
                   
                 AANTWSGGPTY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 119) 
               
               
                   
                 SCISSDGSTG; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NQ: 120) 
               
               
                   
                 SCYSSSDGSTG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 121) 
               
               
                   
                 SCISSDGSTG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 122) 
               
               
                   
                 GCIKSSDGTTG; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 123) 
               
               
                   
                 SCISNTDSSTY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 124) 
               
               
                   
                 AAIAWSAGSTY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 125) 
               
               
                   
                 SCISSKEGSTY; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 126) 
               
               
                   
                 SCISSSDGSTG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 127) 
               
               
                   
                 SCYSSRDGTTG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 128) 
               
               
                   
                 SCISSDGSTG; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 129) 
               
               
                   
                 SCYSSSDGSTG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 130) 
               
               
                   
                 SCFSSSDGSTG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 131) 
               
               
                   
                 SCISNTDSSTF; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 132) 
               
               
                   
                 SCYSSSDGSTG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 133) 
               
               
                   
                 SCISNTDSSTY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 134) 
               
               
                   
                 SCISSSDGSTG; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 135) 
               
               
                   
                 GGINWSGDSTD;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 136) 
               
               
                   
                 SCFSSSDGSAG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 137) 
               
               
                   
                 SCISNTDSSTY; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 138) 
               
               
                   
                 SCFSTRDGNAG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 139) 
               
               
                   
                 SCFSSRDGSTG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 140) 
               
               
                   
                 SCFSSRDGSTG; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 141) 
               
               
                   
                 SCISSDGSTG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 142) 
               
               
                   
                 SCISNTDSSTY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 143) 
               
               
                   
                 SCISSPDGSTY; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 144) 
               
               
                   
                 SCYSSSDGNTG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 145) 
               
               
                   
                 GGINWSGDSTD;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 146) 
               
               
                   
                 SCFSSSDGSTG; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 147) 
               
               
                   
                 SCISSGDGTTY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 148) 
               
               
                   
                 SCISSDGSTG;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 149) 
               
               
                   
                 SCISSDGSTG;  
               
               
                   
                 and 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 1221) 
               
               
                   
                 SSISRSDGSTY. 
               
            
           
         
       
     
     In some embodiments, the CDR3 sequence is selected from: 
     
       
         
           
               
               
            
               
                   
                 (SEQ ID NO: 150) 
               
               
                   
                 AKGLRNSDWDLRRGYEYDY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 151) 
               
               
                   
                 ADQASVPPPYGSERYDIASPSEYDY; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 152) 
               
               
                   
                 ANSRAYYSSSYDLGRLASYDY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 153) 
               
               
                   
                 AAQRLGSVTDYTKYDY; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO:  154) 
               
               
                   
                 ASVKWAGSGIDISGSRNYDY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO:  155) 
               
               
                   
                 AKRLDYSATDKGVDLSDEYDY; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO:  156) 
               
               
                   
                 AAGGSGRLRDLKVGQNYDY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO:  157) 
               
               
                   
                 ADSPPRTYSSGSVNLEDGSEYDY; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 158) 
               
               
                   
                 VIPGRGSALPIDVGKSDEYEY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 159) 
               
               
                   
                 AAGASGRLRDLKVGQNYDY; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NQ: 160) 
               
               
                   
                 ADGNVWSPPICGSAGPPPGGMDY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 161) 
               
               
                   
                 AAQRLGSVTDYTKYDY; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 162) 
               
               
                   
                 AIPPRAYSGGSYSLKDQSKYEY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 163) 
               
               
                   
                 ADGNVWSPPICSSAGPPPGGMDY; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 164) 
               
               
                   
                 KSRSSYSNN;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 165) 
               
               
                   
                 AMPPRAYTGRSVSLKDQSKYEY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 166) 
               
               
                   
                 LDTTGWGPPPYQY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 167) 
               
               
                   
                 AHPPDPSRGGEWRLQTPSEYDY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 168) 
               
               
                   
                 AAQRLGSVTDYTKYDY; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 169) 
               
               
                   
                 VPRSHFTTAQDMGQDMGAPSWYEY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NQ: 170) 
               
               
                   
                 AVLIRYYSGGYQGLSDANEYDY; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 171) 
               
               
                   
                 WKYLSGSYSYAGQYNF;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 172) 
               
               
                   
                 ADFNVWSPPICGSVGPPPGGMDY; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 173) 
               
               
                   
                 AHESTYYSGTYYLTDPRRYVY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 174) 
               
               
                   
                 AVPARGLTMDLENSDIYDH; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 175) 
               
               
                   
                 AATLQVTGSYYLDLSTVDIYDN;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 176) 
               
               
                   
                 ATLFRSNGPKDLSSGYEYDY; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 177) 
               
               
                   
                 AGESGVWVGGLDY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 178) 
               
               
                   
                 VGSANSGEFRFGWVLKPDLYNY; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 179) 
               
               
                   
                 ADGNVWSPPICGSAGPPPGGMDY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NQ: 180) 
               
               
                   
                 ADGNVWSPPICGSAGPPPGGMDY; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 181) 
               
               
                   
                 ERGYAYCSDDGCQRTQDYDY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 182) 
               
               
                   
                 GAARAWWSGSYDYTRMNNYDY; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 183) 
               
               
                   
                 AETSADSGEFRFGWVLKPSLYDY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 184) 
               
               
                   
                 AAGSAYSGSYWNITMAANYDY; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 185) 
               
               
                   
                 AQRIFGAQPMDLSGDYEY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 186) 
               
               
                   
                 ADGNVWSPPICGSAGPPPGGMDY; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 187) 
               
               
                   
                 ARDYRGIKDLDLKGDYDY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 188) 
               
               
                   
                 ADFNVWSPPICGSIWYGPPPRGMDY; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 189) 
               
               
                   
                 ADSNVWSPPICGSRWYGPPPGGMAY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NQ: 190) 
               
               
                   
                 ADFNVWSPPICGSNWYGPPPGGMDY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 191) 
               
               
                   
                 ADFNVWSPPICGSIWYGPPPGGMDY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 192) 
               
               
                   
                 ADGNVWSPPICGSAGPPPGGMDY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 193) 
               
               
                   
                 ARIITVATMRLDSDYDY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 194) 
               
               
                   
                 ADGNVWSPPICGSAGPPPGGMDY; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 195) 
               
               
                   
                 ADSNVWSPPICGRTWYGPPPGGMDY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 196) 
               
               
                   
                 ADFNVWSPPICGSIWYGPPPGGMAY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 197)  
               
               
                   
                 ADFNVWSPPICGSNWYGPPPGGMDY; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 198) 
               
               
                   
                 ADFNVWSPPICGSSWYGPPPGGMDY; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 199) 
               
               
                   
                 ADFNVWSPPICGSRWYGPPPGGMEY; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NQ: 200) 
               
               
                   
                 ADGNVWSPPICGSAGPPPGGMDY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NQ: 201) 
               
               
                   
                 ADFNVWSPPICGSRWYGPPPGGMAY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NQ: 202) 
               
               
                   
                 ADGNVWSPPICGSAGPPPGGMDY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NQ: 203) 
               
               
                   
                 ADSNVWSPPICGKTWYGPPPGGMDY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NQ: 204) 
               
               
                   
                 AGESGVWVGGLDY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 205) 
               
               
                   
                 ADSNVWSPPICGSTWYGPPPGGMAY; 
               
               
                   
                   
               
               
                   
                 (SEQ ID NQ: 206) 
               
               
                   
                 ADGNVWSPPICGSAGPPPGGMDY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NQ: 207) 
               
               
                   
                 ADFNVWSPPICGSRWYGPPPGGMDY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NQ: 208) 
               
               
                   
                 ADFNVWSPPICGSRWYGPPPGGMDY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 209) 
               
               
                   
                 ADFNVWSPPICGSRWYGPPPGGMDY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 210) 
               
               
                   
                 ADFNVWSPPICGSIWYGPPPGGMDY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 211) 
               
               
                   
                 ADGNVWSPPICGSAGPPPGGMDY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 212) 
               
               
                   
                 ADFNVWSPPICGSVGPPPGGMDY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 213) 
               
               
                   
                 ADFNVWSPPICGSSWYGPPPGGMAY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 214) 
               
               
                   
                 AGESGVWGGLDY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 215) 
               
               
                   
                 ADFNVWSPPICGSSWYGPPPGGMEY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 216) 
               
               
                   
                 ADGNVWSPPICGSAGPPPGGMDY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 217) 
               
               
                   
                 ADFNVWSPPICSSNWYGPPPRGMDY;  
               
               
                   
                   
               
               
                   
                 (SEQ ID NO: 218) 
               
               
                   
                 ADFNVWSPPICGSIWYGPPPRGMDY. 
               
            
           
         
       
     
     In various embodiments, the CD8 binding agent comprises an amino acid sequence selected from the following sequences: 
     
       
         
           
               
               
            
               
                 1CDA 7 
                   
               
               
                 (SEQ ID NO: 219) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGRSFSSYTLAWFRQAPGKEREFVASITWGGGNTYYPDSVKGRFTISRD 
                   
               
               
                   
               
               
                 DAKNTVYLQMNSLKPEDTAVYYCAAKGLRNSDWDLRRGYEYDYWGQGTQVTVSSAAAYPYDVPDYGSHHHHH 
               
               
                   
               
               
                 H; 
               
               
                   
               
               
                 1CDA 12 
               
               
                 (SEQ ID NO: 220) 
                   
               
               
                 QVQLQESGGGLVQDGGSLRLSCAFSGRTFSSYTMGWFRQGPGKEREFVAATVWTGAGTVYADSVKGRFTISR 
                   
               
               
                   
               
               
                 DNAKNTVYLQMNSLRPEDTAVYYCAADQASVPPPYGSERYDIASPSEYDYWGQGTQVTVSSAAAYPYDVPDYG 
               
               
                   
               
               
                 SHHHHHH; 
               
               
                   
               
               
                 1CDA 14 
               
               
                 (SEQ ID NO: 221) 
                   
               
               
                 QVQLQESGGGLVQAGASLRLSCAASGRTFSSYIMGWFRQAPGKEREFVAAIGWSADITVYADSVKGRFTISRDN 
                   
               
               
                   
               
               
                 AENMVYLQMNSLNPEDTAVYYCAANSRAYYSSSYDLGRLASYDYWGQGTQVTVSSAAAYPYDVPDYGSHHHH 
               
               
                   
               
               
                 HH; 
               
               
                   
               
               
                 1CDA 15 
               
               
                 (SEQ ID NO: 222) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGRTFSSYTMGWFRQAPGKEREFVAFIDWSGGGTYYDDSVKGRFTISR 
                   
               
               
                   
               
               
                 DNAENTVYLQMNNLEPEDTAVYYCAAAQRLGSVTDYTKYDYWGQGTQVTVSSAAAYPYDVPDYGSHHHHHH; 
               
               
                   
               
               
                 1CDA 17 
               
               
                 (SEQ ID NO: 223) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGRTSGRTFSSYTMGWFRQAPGKEREFVATITWGGGSTYYADSVKGRF 
                   
               
               
                   
               
               
                 TISRDNANNTVYLQMNSLKPEDTAVYYCAASVKWAGSGIDISGSRNYDYWGQGTQVTVSSAAAYPYDVPDYGS 
               
               
                   
               
               
                 HHHHHH; 
               
               
                   
               
               
                 1CDA 18 
               
               
                 (SEQ ID NO: 224) 
                   
               
               
                 QVQLQESGGGLVQPGGSLRLSCLASGRTFSSYAMGWFRQAPGKEREFVAAISWSGGPTVYADHVKGRFTISRD 
                   
               
               
                   
               
               
                 NAKNTVYLQVNSLKPEDTADYYCAAKRLDYSATDKGVDLSDEYDYWGQGTQVTVSSAAAYPYDVPDYGSHHHH 
               
               
                   
               
               
                 HH; 
               
               
                   
               
               
                 1CDA 19 
               
               
                 (SEQ ID NO: 225) 
                   
               
               
                 QVQLQESGGGLVQAGDSLRLSCAASGLTFSNYIMGWFRQAPGKEREFVAAITWGGGSTVYADSVEGRFTISRD 
                   
               
               
                   
               
               
                 GTKNTVSLQMNSLLPEDTAVYYCAAAGGSGRLRDLKVGQNYDYWGQGTQVTVSSAAAYPYDVPDYGSHHHHH 
               
               
                   
               
               
                 H; 
               
               
                   
               
               
                 1CDA 24 
               
               
                 (SEQ ID NO: 226) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGRTFSSYTMGWFRQAPGREREFVAAITWSGVSTVYTDSVKGRFTVSR 
                   
               
               
                   
               
               
                 DNAKNTVYLQMNSLKPEDTAVYYCAADSPPRTYSSGSVNLEDGSEYDYWGQGTQVTVSSAAAYPYDVPDYGS 
               
               
                   
               
               
                 HHHHHH; 
               
               
                   
               
               
                 1CDA 26 
               
               
                 (SEQ ID NO: 227) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGRTFSSDTMGWFRQAPGKEREFVGAIMWSGAFTHYADSVKGRFTISR 
                   
               
               
                   
               
               
                 DNAKNTVYLQMNALKPEDTAVYYCAVIPGRGSALPIDVGKSDEYEYWGQGTQVTVSSAAAYPYDVPDYGSHHH 
               
               
                   
               
               
                 HHH; 
               
               
                   
               
               
                 1CDA 28 
               
               
                 (SEQ ID NO: 228) 
                   
               
               
                 QVQLQESGGGLVQAGDSLRLSCAASGLTFSNYIMGWFRQAPGKEREFVAAITWGGGSTVYADSVEGRFTISRD 
                   
               
               
                   
               
               
                 GTKNTVSLQMNSLQPEDTAVYYCAAAGASGRLRDLKVGQNYDYWGQGTQVTVSSAAAYPYDVPDYGSHHHHH 
               
               
                   
               
               
                 H; 
               
               
                   
               
               
                 1CDA 37 
               
               
                 (SEQ ID NO: 229) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAGSGFTLDYYGIGWFRQAPGKEREGVSCISSSDRNTYYADSVKGRFTISGD 
                   
               
               
                   
               
               
                 NAKNTVYLQMNNLKPEDTAVYYCAADGNVWSPPICGSAGPPPGGMDYWGKGTQVTVSSAAAYPYDVPDYGSH 
               
               
                   
               
               
                 HHHHH; 
               
               
                   
               
               
                 1CDA 43 
               
               
                 (SEQ ID NQ: 230) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCVASGHTFSSYTMGWFRQAPGKEREFVAFIDWSGGGTYYANSVKGRFTISR 
                   
               
               
                   
               
               
                 DNAENTVYLQMNNLKPEDTAVYYCAAAQRLGSVTDYTKYDYWGQGTQVTVSSAAAYPYDVPDYGSHHHHHH; 
               
               
                   
               
               
                 1CDA 45 
               
               
                 (SEQ ID NO: 231) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGRTFSSYVIGWFRQAPGKEREFVAVITWSGDSTYSSDSLKGRFTISRDN 
                   
               
               
                   
               
               
                 AKNTVYLQMNALNPEDTAVYYCAAIPPRAYSGGSYSLKDQSKYEYWGQGTQVTVSSAAAYPYDVPDYGSHHHH 
               
               
                   
               
               
                 HH; 
               
               
                   
               
               
                 1CDA 47 
               
               
                 (SEQ ID NO: 232) 
                   
               
               
                 QVQLQESGGGLVQAEGSLKLSCISGFAFDGYAIGWFRQAPGKEREGVACISSKDGSTYYADSVKGRFTMSVDK 
                   
               
               
                   
               
               
                 TKNTVYLQMSSLKPEDTAVYYCAADGNVWSPPICSSAGPPPGGMDYWGKGTQVTVSSAAAYPYDVPDYGSHH 
               
               
                   
               
               
                 HHHH; 
               
               
                   
               
               
                 1CDA 48 
               
               
                 (SEQ ID NO: 233) 
                   
               
               
                 QVQLQESGGGLVQPGGSLTLSCAASGFAFGFFDMTWVRQAPGKGLEWVSGINSIGGSTTYADSVKGRFTISRD 
                   
               
               
                   
               
               
                 NAKNELYLQMNSLKPDDTAVYYCAKSRSSYSNNWRPPGQGTQVTVSSAAAYPYDVPDYGSHHHHHH; 
               
               
                   
               
               
                 1CDA 58 
               
               
                 (SEQ ID NO: 234) 
                   
               
               
                 QVQLQESGGGLVQARGSLTLSCAASGRTFSNYVIGWFRQAPGEEREFVAWTWSGDSTYSSDSLKGRFTISRD 
                   
               
               
                   
               
               
                 NAKNTVYLQMNNLNPEDTAVYYCAAMPPRAYTGRSVSLKDQSKYEYWGQGTQVTVSSAAAYPYDVPDYGSHH 
               
               
                   
               
               
                 HHHH; 
               
               
                   
               
               
                 1CDA 65 
               
               
                 (SEQ ID NO: 235) 
                   
               
               
                 QVQLQESGGGLVQPGGSLRLSCAASGSIFSINVMGWYRQTPGKERELVAKITNFGITSYADSAQGRFTISRGNAK 
                   
               
               
                   
               
               
                 NTVYLQMNSLKPEDTAVYYCNLDTTGWGPPPYQYWGQGTQVTVSSAAAYPYDVPDYGSHHHHHH; 
               
               
                   
               
               
                 1CDA 68 
               
               
                 (SEQ ID NO: 236) 
                   
               
               
                 QVQLQESGGGLVQAGASLRLSCAASGRTFSNYNVGWFRQAPGKEREFVSFISWISDITYYSDSVKGRFIISRDNA 
                   
               
               
                   
               
               
                 KNMVYLQMNSLKPEDTAVYYCAAHPPDPSRGGEWRLQTPSEYDYWGQGTQVTVSSAAAYPYDVPDYGSHHH 
               
               
                   
               
               
                 HHH; 
               
               
                   
               
               
                 1CDA 73 
               
               
                 (SEQ ID NO: 237) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGHTFSSYTMGWFRQAPGKEREFVAFIDWSGGGTYYADSVKGRFTISR 
                   
               
               
                   
               
               
                 DNAENTVYLQMNNLKPEDTAVYYCAAAQRLGSVTDYTKYDYWGQGTQVTVSSAAAYPYDVPDYGSHHHHHH; 
               
               
                   
               
               
                 1CDA 75 
               
               
                 (SEQ ID NO: 238) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGRTFSTYPVGWFRQAPGKEREFVAVILWSGVSTYYADSVKGRFTISRD 
                   
               
               
                   
               
               
                 NAQNTVYLQMDSLKPEDTAVYYCAVPRSHFTTAQDMGQDMGAPSWYEYWGQGTQVTVSSAAAYPYDVPDYG 
               
               
                   
               
               
                 SHHHHHH; 
               
               
                   
               
               
                 1CDA 86 
               
               
                 (SEQ ID NO: 239) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGRTFSNYAMGWFRQAPGKEREFVAAIVWSGGSTYYADSVKGRFTISR 
                   
               
               
                   
               
               
                 DNAKNTVYLQMNSLKPEDTAVYYCAAVLIRYYSGGYQGLSDANEYDYWGQGTQVTVSSAAAYPYDVPDYGSHH 
               
               
                   
               
               
                 HHHH; 
               
               
                   
               
               
                 1CDA 87 
               
               
                 (SEQ ID NO: 240) 
                   
               
               
                 QVQLQESGGGLVQAGASLRLSCSASGRTFSDYRMGWFRQAPGKEREWVAAISSSGYHTYYADSVKGRFTISR 
                   
               
               
                   
               
               
                 DNAKNTGYLQMSSLKPEDTAVYYCAWVKYLSGSYSYAGQYNFWGQGTQVTVSSAAAYPYDVPDYGSHHHHHH; 
               
               
                   
               
               
                 1CDA 88 
               
               
                 (SEQ ID NO: 241) 
                   
               
               
                 QVQLQESGGGLVQAGDSLKLSCAASGLTFSNYIMAWFRQAPGKEREGVSCISSPDGSTYYADSVKGRFTISSDN 
                   
               
               
                   
               
               
                 AKNTVYLQMNSLKPEDTAVYYCAADFNVWSPPICGSVGPPPGGMDYWGKGTQVTVSSAAAYPYDVPDYGSHH 
               
               
                   
               
               
                 HHHH; 
               
               
                   
               
               
                 1CDA 89 
               
               
                 (SEQ ID NO: 242) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGRTFSNSVMGWFRQPPGKEREFVAAVLWSGVSTAYADSVKGRFTISR 
                   
               
               
                   
               
               
                 DNAKNTVYLQMNNLKPDDTAVYYCAAHESTYYSGTYYLTDPRRYVYWGQGTQVTVSSAAAYPYDVPDYGSHH 
               
               
                   
               
               
                 HHHH; 
               
               
                   
               
               
                 1CDA 92 
               
               
                 (SEQ ID NO: 243) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCVGDGRTFSSYIIGWFRQAPGNEREFWAITWDGSATTYADSVKGRFTVSRD 
                   
               
               
                   
               
               
                 SAKNTAYLQMNSLKPEDTAVYYCAAVPARGLTMDLENSDIYDHWGRGTQVTVSSAAAYPYDVPDYGSHHHHH; 
               
               
                   
               
               
                 1CDA 93 
               
               
                 (SEQ ID NO: 244) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGRTFSSYVMGWFRQALGKEREFVAAIGWNGGITYYADSVKGRFAISRD 
                   
               
               
                   
               
               
                 NAKNTVYLQMNSLKPEDTAVYYCAAATLQVTGSYYLDLSTVDIYDNWGQGTQVTVSSAAAYPYDVPDYGSHHH 
               
               
                   
               
               
                 HHH; 
               
               
                   
               
               
                 2CDA 1 
               
               
                 (SEQ ID NO: 245) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGGTFSNYVMGWFRQAPGKEREFVGFITWSGASTYYADSVKGRFTISR 
                   
               
               
                   
               
               
                 DNAENTVYLQMNSLKPEDTAVYYCAATLFRSNGPKDLSSGYEYDYWGQGTQVTVSSAAAYPYDVPDYGSHHH 
               
               
                   
               
               
                 HHH; 
               
               
                   
               
               
                 2CDA 5 
               
               
                 (SEQ ID NO: 246) 
                   
               
               
                 QVQLQESGGGLVQAGDSLRLTCTASGRTFSNYGIGWFRQAPGKEREFVAGINWSGESADYADSVKGRFTISRD 
                   
               
               
                   
               
               
                 NAKNTVYLQMNSLKPEDTAVYYCAAGESGVWVGGLDYWXQGTQVTVSSAAAYPYDVPDYGSHHHHHH; 
               
               
                   
               
               
                 2CDA 22 
               
               
                 (SEQ ID NO: 247) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGFTFDDYAIAWFRQAPGKEREGVSCIERSDGSTYYADSVKGRFTISSDN 
                   
               
               
                   
               
               
                 AKNTVYLQMNSLKPEDTAVYYCAVGSANSGEFRFGWVLKPDLYNYWGQGTQVTVSSAAAYPYDVPDYGSHHH 
               
               
                   
               
               
                 HHH; 
               
               
                   
               
               
                 2CDA 28 
               
               
                 (SEQ ID NO: 248) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCTASGRTFSSYTVAWFRQSPGKEREGISCISNTDSSTYYADSVKGRFTISSDN 
                   
               
               
                   
               
               
                 AKSTVHLQMSSLKPEDTAVYYCAADGNVWSPPICGSAGPPPGGMDYWGKGTQVTVSSAAAYPYDVPDYGSHH 
               
               
                   
               
               
                 HHHH; 
               
               
                   
               
               
                 2CDA 62 
               
               
                 (SEQ ID NO: 249) 
                   
               
               
                 QVQLQESGGGLVQPGGSLRLSCATFGFPFDDYAIAWFRQAPGKEREGVSCISNTDSSTYYADSVKGRFTISSDN 
                   
               
               
                   
               
               
                 AKNTVHLQMSSLKPEDTAVYYCAADGNVWSPPICGSAGPPPGGMDYWGKGTQVTVSSAAAYPYDVPDYGSHH 
               
               
                   
               
               
                 HHHH; 
               
               
                   
               
               
                 2CDA 68 
               
               
                 (SEQ ID NO: 250) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGRTFSSYVMGWFRQAPGKEREFVAQISWSAGSIYYADSVKGRFTISND 
                   
               
               
                   
               
               
                 NAKRTVYLQMNSLKPEDTAVYYCAERGYAYCSDDGCQRTQDYDYWGQGTQVTVSSAAAYPYDVPDYGSHHH 
               
               
                   
               
               
                 HHH; 
               
               
                   
               
               
                 2CDA 73 
               
               
                 (SEQ ID NO: 251) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGRTLSSNPMAWFRQAAGKEREFVAGMSWNPGPAVYADSVKGRFTISR 
                   
               
               
                   
               
               
                 DSAENTVYLQMNSLKPEDTAVYYCAGAARAWWSGSYDYTRMNNYDYWGPGTQVTVSSAAAYPYDVPDYGSH 
               
               
                   
               
               
                 HHHHH; 
               
               
                   
               
               
                 2CDA 74 
               
               
                 (SEQ ID NO: 252) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAVSGFTFDNYAIGWFRQAPGKEREGVSCISRSDGSTYYADSVRGRFTISSD 
                   
               
               
                   
               
               
                 NAKNTVYLQMNSLKPEDTAVYYCAAETSADSGEFRFGWVLKPSLYDYWGQGTQVTVSSAAAYPYDVPDYGSH 
               
               
                   
               
               
                 HHHHH; 
               
               
                   
               
               
                 2CDA 74(C50S) 
               
               
                 (SEQ ID NO: 216) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAVSGFTFDNYAIGWFRQAPGKEREGVSSISRSDGSTYYADSVRGRFTISSD 
                   
               
               
                   
               
               
                 NAKNTVYLQMNSLKPEDTAVYYCAAETSADSGEFRFGWVLKPSLYDYWGQGTQVTVSS; 
               
               
                   
               
               
                 2CDA 75 
               
               
                 (SEQ ID NO: 253) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGRAFSSYFMGWFRQTPGKEREFVANIGWTGDMTYYADSVKGRFTISR 
                   
               
               
                   
               
               
                 DNAKNTVYLQMNSLKPEDTAVYYCAAAGSAYSGSYWNITMAANYDYWGQGTQVTVSSAAAYPYDVPDYGSHH 
               
               
                   
               
               
                 HHHH; 
               
               
                   
               
               
                 2CDA 77 
               
               
                 (SEQ ID NO: 254) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASTPTFSSYNMGWFRQAPGKEREFVAAIIWSGSMTYYADSMKGRFTVSID 
                   
               
               
                   
               
               
                 NAKNTVYLQMNSLKPEDTAVYYCAAQRIFGAQPMDLSGDYEYWGQGTQVTVSSAAAYPYDVPDYGSHHHHHH; 
               
               
                   
               
               
                 2CDA 81 
               
               
                 (SEQ ID NO: 255) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCATFGFTFDDYAIAWFRQAPGKEREGISCISNTDSSTYYADSVKGRFTISSDSA 
                   
               
               
                   
               
               
                 KNTVHLQMSSLKPEDTAVYYCAADGNVWSPPICGSAGPPPGGMDYWGKGTQVTVSSAAAYPYDVPDYGSHHH 
               
               
                   
               
               
                 HHH; 
               
               
                   
               
               
                 2CDA 87 
               
               
                 (SEQ ID NO: 256) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCKASGGTFSGYIMGWFRQAPGKEREFVAANTWSGGPTYYSDSVKGRFTISR 
                   
               
               
                   
               
               
                 DNAKNTVYLQMNTLKPEDTAVYQCAARDYRGIKDLDLKGDYDYWGQGTQVTVSSAAAYPYDVPDYGSHHHHH 
               
               
                   
               
               
                 H; 
               
               
                   
               
               
                 2CDA 88 
               
               
                 (SEQ ID NO: 257) 
                   
               
               
                 QVQLQESGGGLVQAGDSLKLSCATSGRSFSSYTIAWFRQAPGKEREGISCISSDGSTGYADSVRGRFTISSDNA 
                   
               
               
                   
               
               
                 KNTVYLQMNSLKPEDTAVYYCAADFNVWSPPICGSIWYGPPPRGMDYWGKGTQVTVSSAAAYPYDVPDYGSH 
               
               
                   
               
               
                 HHHHH; 
               
               
                   
               
               
                 2CDA 89 
               
               
                 (SEQ ID NO: 258) 
                   
               
               
                 QVQLQESGGGLVQAGGYLRLSCAASGFSSDDYTIGWFRQAPGKEREGISCYSSSDGSTGFADSVKGRFTISSD 
                   
               
               
                   
               
               
                 NAKNTVYLQMNNLRPEDTAVYYCAADSNVWSPPICGSRWYGPPPGGMAYWGKGTQVTVSSAAAYPYDVPDY 
               
               
                   
               
               
                 GSHHHHHH; 
               
               
                   
               
               
                 2CDA 91 
               
               
                 (SEQ ID NO: 259) 
                   
               
               
                 QVQLQESGGGLAQVGGSLRLSCTASGFTFDDYTIGWFRQAPGKEREGISCISSDGSTGYADSVKGRFTISSDNA 
                   
               
               
                   
               
               
                 KNTVYLQMNSLKPEDTAVYYCAADFNVWSPPICGSNWYGPPPGGMDYWGKGTQVTVSSAAAYPYDVPDYGSH 
               
               
                   
               
               
                 HHHHH; 
               
               
                   
               
               
                 2CDA 92 
               
               
                 (SEQ ID NQ: 260) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGFSSDDYTIGWFRQAPGKEREGIGCIKSSDGTTGYADSVKGRFTISSDN 
                   
               
               
                   
               
               
                 AKNTVYLQMNSLKPEDTAVYYCAADFNVWSPPICGSIWYGPPPGGMDYWGKGTQVTVSSAAAYPYDVPDYGS 
               
               
                   
               
               
                 HHHHHH; 
               
               
                   
               
               
                 2CDA 93 
               
               
                 (SEQ ID NO: 261) 
                   
               
               
                 QVQLQESGGGLAQAGGSLRLSCAASGFTFDQYTIAWFRQAPGKEREGVSCISNTDSSTYYADSVKGRFTISSDN 
                   
               
               
                   
               
               
                 AKNTVYLQMSSLKPEDTAVYYCAADGNVWSPPICGSAGPPPGGMDYWGKGTQVTVSSAAAYPYDVPDYGSHH 
               
               
                   
               
               
                 HHHH; 
               
               
                   
               
               
                 2CDA 94 
               
               
                 (SEQ ID NO: 262) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGRTFSSYAMAWFRQAPGKEREFVAAIAWSAGSTYYADSVKGRFAISRD 
                   
               
               
                   
               
               
                 NAENTVYLQMNSLKPEDTAVYYCAARIITVATMRLDSDYDYWGQGTQVTVSSAAAYPYDVPDYGSHHHHHH; 
               
               
                   
               
               
                 2CDA 95 
               
               
                 (SEQ ID NO: 263) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGFAFDGYAIGWFRQAPGKEREGVSCISSKEGSTYYADSVKGRFTISSD 
                   
               
               
                   
               
               
                 NAKNTVYLQMSSLKPEDTAVYYCAADGNVWSPPICGSAGPPPGGMDYWGKGTQVTVSSAAAYPYDVPDYGSH 
               
               
                   
               
               
                 HHHHH; 
               
               
                   
               
               
                 3CDA 3 
               
               
                 (SEQ ID NO: 264) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGFSSDDYTIAWFRRAPGKEREGISCISSSDGSTGYADSVKGRFTITSDS 
                   
               
               
                   
               
               
                 AKNTVYLQMNSLKPEDTAVYYCAADSNVWSPPICGRTWYGPPPGGMDYWGKGTQVTVSSAAAYPYDVPDYGS 
               
               
                   
               
               
                 HHHHHH; 
               
               
                   
               
               
                 3CDA 8 
               
               
                 (SEQ ID NO: 265) 
                   
               
               
                 QVQLQESGGGLVQPGGSLRLSCAASGFSSDDYTIGWFRQAPGKEREGISCYSSRDGTTGYADSVKGRFTISSD 
                   
               
               
                   
               
               
                 NAKNTVYLQMNSLKPEDTAVYYCAADFNVWSPPICGSIWYGPPPGGMAYWGQGTQVTVSSAAAYPYDVPDYG 
               
               
                   
               
               
                 SHHHHHH; 
               
               
                   
               
               
                 3CDA 11 
               
               
                 (SEQ ID NO: 266) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGFTFDDYTIGWFRQAPGKEREGISCISSDGSTGYADSVKGRFTISSDNA 
                   
               
               
                   
               
               
                 KNTVYLQMNSLKPEDTAVYYCAADFNVWSPPICGSNWYGPPPGGMDYWGKGTQVTVSSAAAYPYDVPDYGSH 
               
               
                   
               
               
                 HHHHH; 
               
               
                   
               
               
                 3CDA 18 
               
               
                 (SEQ ID NO: 267) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGFSSDDYTIGWFRQAPGKEREGISCYSSSDGSTGYADSVKGRFTISSD 
                   
               
               
                   
               
               
                 NAKNTVYLQMNSLKPEDTAVYYCAADFNVWSPPICGSSWYGPPPGGMDYWGKGTQVTVSSAAAYPYDVPDYG 
               
               
                   
               
               
                 SHHHHHH; 
               
               
                   
               
               
                 3CDA 19 
               
               
                 (SEQ ID NO: 268) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGFSSDDYTIGWFRQAPGKEREGISCFSSSDGSTGFADSVKGRFTISSD 
                   
               
               
                   
               
               
                 NATNTVYLEMNSLKPEDTAVYYCAADFNVWSPPICGSRWYGPPPGGMEYWGKGTQVTVSSAAAYPYDVPDYG 
               
               
                   
               
               
                 SHHHHHH; 
               
               
                   
               
               
                 3CDA 21 
               
               
                 (SEQ ID NO: 269) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCATFGFSFDDYAIAWFRQAPGKEREGISCISNTDSSTFYADSVKGRFTISSDNA 
                   
               
               
                   
               
               
                 KNTVHLQMSSLKPEDTAVYYCAADGNVWSPPICGSAGPPPGGMDYWGKGTQVTVSSAAAYPYDVPDYGSHHH 
               
               
                   
               
               
                 HHH; 
               
               
                   
               
               
                 3CDA 24 
               
               
                 (SEQ ID NQ: 270) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGFSSDDYTIGWFRQAPGKEREGISCYSSSDGSTGFADSVKGRFTISSD 
                   
               
               
                   
               
               
                 NAKNTVYLQMNSLRPEDTAVYYCAADFNVWSPPICGSRWYGPPPGGMAYWGKGTQVTVSSAAAYPYDVPDYG 
               
               
                   
               
               
                 SHHHHHH; 
               
               
                   
               
               
                 3CDA 28 
               
               
                 (SEQ ID NO: 271) 
                   
               
               
                 QVQLQESGGGLVQVGGSLRLSCTISGFTGNDLAIGWFRQAPGKDQREGISCISNTDSSTYYADSVKGRFTISSDN 
                   
               
               
                   
               
               
                 AKNTVHLQMSSLKPEDTAVYYCAADGNVWSPPICGSAGPPPGGMDYWGKGTQVTVSSAAAYPYDVPDYGSHH 
               
               
                   
               
               
                 HHHH; 
               
               
                   
               
               
                 3CDA 29 
               
               
                 (SEQ ID NO: 272) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGFSSDDYTIAWFRRAPGKEREGISCISSSDGSTGYADSVKGRFTISSDN 
                   
               
               
                   
               
               
                 AKNTVYLQMTSLKPEDTAVYYCAADSNVWSPPICGKTWYGPPPGGMDYWGKGTQVTVSSAAAYPYDVPDYGS 
               
               
                   
               
               
                 HHHHHH; 
               
               
                   
               
               
                 3CDA 31 
               
               
                 (SEQ ID NO: 273) 
                   
               
               
                 QVQLQESGGGLVQAGDSLRLSCAGSEGTLSSYGIGWFRQAPGKEREFVGGINWSGDSTDYADSVKGRFTISRD 
                   
               
               
                   
               
               
                 SAKNTVYLQMNSLKPEDTAVYYCAAGESGVWVGGLDYWGQGTQVTVSSAAAYPYDVPDYGSHHHHHH; 
               
               
                   
               
               
                 3CDA 32 
               
               
                 (SEQ ID NO: 274) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGFSSDDYTIAWFRRAPGKEREGISCFSSSDGSAGYADSVKGRFTVSSD 
                   
               
               
                   
               
               
                 NAKNTVYLQMNSLKPEDTAVYYCAADSNVWSPPICGSTWYGPPPGGMAYWGKGTQVTVSSAAAYPYDVPDYG 
               
               
                   
               
               
                 SHHHHHH; 
               
               
                   
               
               
                 3CDA 33 
               
               
                 (SEQ ID NO: 275) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCATSGFTFDDYAIAWFRQAPGKEREGVSCISNTDSSTYYADSVKGRFTISSDN 
                   
               
               
                   
               
               
                 AKNTVYLQMSSLKPEDTAVYYCAADGNVWSPPICGSAGPPPGGMDYWGKGTQVTVSSAAAYPYDVPDYGSHH 
               
               
                   
               
               
                 HHHH; 
               
               
                   
               
               
                 3CDA 37 
               
               
                 (SEQ ID NO: 276) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCEVSGLSSDDYTIGWFRQAPGKEREGFSCFSTRDGNAGYADSVKGRFTISSD 
                   
               
               
                   
               
               
                 NAKNTVYLQMNNLKPEDTAVYYCAADFNVWSPPICGSRWYGPPPGGMDYWGKGTQVTVSSAAAYPYDVPDYG 
               
               
                   
               
               
                 SHHHHHH; 
               
               
                   
               
               
                 3CDA 40 
               
               
                 (SEQ ID NO: 277) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCEVSGLSSDDYTIGWFRQAPGKKREGFSCFSSRDGSTGYADSVKGRFTISSD 
                   
               
               
                   
               
               
                 NAKNTVYLQMNSLKPEDTAVYYCAADFNVWSPPICGSRWYGPPPGGMDYWGKGTQVTVSSAAAYPYDVPDYG 
               
               
                   
               
               
                 SHHHHHH; 
               
               
                   
               
               
                 3CDA 41 
               
               
                 (SEQ ID NO: 278) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGFSSDDYTIGWFRQAPGKEREGFSCFSSRDGSTGYADSVKGRFTISSD 
                   
               
               
                   
               
               
                 NAKNTVYLQMNSLKPEDTAVYYCAADFNVWSPPICGSRWYGPPPGGMDYWGKGTQVTVSSAAAYPYDVPDYG 
               
               
                   
               
               
                 SHHHHHH; 
               
               
                   
               
               
                 3CDA 48 
               
               
                 (SEQ ID NO: 279) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGFSFDDYTIGWFRQVPGKEREGISCISSDGSTGYADSVKGRFTISSDNA 
                   
               
               
                   
               
               
                 KNTVYLQINSLKPEDTAVYYCAADFNVWSPPICGSIWYGPPPGGMDYWGKGTQVTVSSAAAYPYDVPDYGSHH 
               
               
                   
               
               
                 HHHH; 
               
               
                   
               
               
                 3CDA 57 
               
               
                 (SEQ ID NQ: 280) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCATFGFTFDDYAIAWFRQAPGKEREGISCISNTDSSTYYADSVKGRFTISSDNA 
                   
               
               
                   
               
               
                 KNTVHLQMSSLKPEDTAVYYCAADGNVWSPPICGSAGPPPGGMDYWGKGTQVTVSSAAAYPYDVPDYGSHHH 
               
               
                   
               
               
                 HHH; 
               
               
                   
               
               
                 3CDA 65 
               
               
                 (SEQ ID NO: 281) 
                   
               
               
                 QVQLQESGGGLVQAGGSLXLSCAASGFTFDDYAIGWFRQAPGKEREGVSCISSPDGSTYYADSVKGRFTISSDN 
                   
               
               
                   
               
               
                 AKNTVYLQMNSLKPEDTAVYYCAADFNVWSPPICGSVGPPPGGMDYWGKGTQVTVSSAAAYPYDVPDYGSHH 
               
               
                   
               
               
                 HHHH; 
               
               
                   
               
               
                 3CDA 70 
               
               
                 (SEQ ID NO: 282) 
                   
               
               
                 QVQLQESGGGLVQAGASLRLSCKASGFTFGDYTIGWFRQAPGKEREGISCYSSSDGNTGYADSVKGRFTISSD 
                   
               
               
                   
               
               
                 NAKNTVYLQMNSLRPEDTAVYYCAADFNVWSPPICGSSWYGPPPGGMAYWGKGTQVTVSSAAAYPYDVPDYG 
               
               
                   
               
               
                 SHHHHHH; 
               
               
                   
               
               
                 3CDA 73 
               
               
                 (SEQ ID NO: 283) 
                   
               
               
                 QVQLQESGGGLVQAGDSLRLSCAGSEGTFSSYGIGWFRQAPGKEREFVGGINWSGDSTDYADSVKGRFTISRD 
                   
               
               
                   
               
               
                 NAKNTVYLQMNSLKPEDTAVYYCAAGESGVWVGGLDYWGQGTQVTVSSAAAYPYDVPDYGSHHHHHH; 
               
               
                   
               
               
                 3CDA 83 
               
               
                 (SEQ ID NO: 284) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGFSSDDYTIGWFRQAPGKEREGISCFSSSDGSTGFADSVKGRFTISSD 
                   
               
               
                   
               
               
                 NATNTVYLQMNSLKPEDTAVYYCAADFNVWSPPICGSSWYGPPPGGMEYWGKGTQVTVSSAAAYPYDVPDYG 
               
               
                   
               
               
                 SHHHHHH; 
               
               
                   
               
               
                 3CDA 86 
               
               
                 (SEQ ID NO: 285) 
                   
               
               
                 QVQLQESGGGLVQAGDSLRLSCTASGVSIGDYNIGWFRQAPGKEREGVSCISSGDGTTYYTDSVKGRFTISTDN 
                   
               
               
                   
               
               
                 AKNTVYLQMNSLKPEDTAVYYCAADGNVWSPPICGSAGPPPGGMDYWGKGTQVTVSSAAAYPYDVPDYGSHH 
               
               
                   
               
               
                 HHHH; 
               
               
                   
               
               
                 3CDA 88 
               
               
                 (SEQ ID NO: 286) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGFTFDDYTIAWFRQAPGGKEREGISCISSDGSTGYADSVKGRFTISSDN 
                   
               
               
                   
               
               
                 AKNMVYLQMNSLKPEDTALYYCAADFNVWSPPICSSNWYGPPPRGMDYWGKGTQVTVSSAAAYPYDVPDYGS 
               
               
                   
               
               
                 HHHHHH; 
               
               
                 or 
               
               
                   
               
               
                 3CDA 90 
               
               
                 (SEQ ID NO: 287) 
                   
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGFTFDDYTIAWFRQAPGKEREGISCISSDGSTGYADSVRGRFTISSDNA 
                   
               
               
                   
               
               
                 KNTVYLQMNSLKPEDTAVYYCAADFNVWSPPICGSIWYGPPPRGMDYWGKGTQVTVSSAAAYPYDVPDYGSH 
               
               
                   
               
               
                 HHHHH. 
               
            
           
         
       
     
     In various exemplary embodiments, the CD8 binding agent comprises an amino acid sequence selected from any one of the above sequences without the terminal histidine tag sequence (i.e., HHHHHH, SEQ ID NO: 1213). 
     In some embodiments, the CD8 binding agent comprises an amino acid sequence selected from any one of the above sequences without the HA tag (i.e., YPYDVPDYGS; SEQ ID NO: 1214). 
     In some embodiments, the CD8 binding agent comprises an amino acid sequence selected from any one of the above sequences without the AAA linker. 
     In some embodiments, the CD8 binding agent comprises an amino acid sequence selected from any one of the above sequences without the AAA linker, HA tag, and terminal histidine tag sequence (i.e., 
     
       
         
           
               
               
            
               
                   
                 AAAYPYDVPDYGSHHHHHH; SEQ ID NO: 1215) 
               
            
           
         
       
     
     In various embodiments, the present invention contemplates the use of any natural or synthetic analogs, mutants, variants, alleles, homologs and orthologs (herein collectively referred to as “analogs”) of the CD8 binding agent of the invention as described herein. In various embodiments, the amino acid sequence of the CD8 binding agent further includes an amino acid analog, an amino acid derivative, or other non-classical amino acids. 
     In various embodiments, the CD8 binding agent comprises a targeting moiety comprising a sequence that is at least 60% identical to any one of the sequences disclosed herein. For example, the CD8 binding agent may comprise a targeting moiety comprising a sequence that is at least about 60%, at least about 61%, at least about 62%, at least about 63%, at least about 64%, at least about 65%, at least about 66%, at least about 67%, at least about 68%, at least about 69%, at least about 70%, at least about 71%, at least about 72%, at least about 73%, at least about 74%, at least about 75%, at least about 76%, at least about 77%, at least about 78%, at least about 79%, at least about 80%, at least about 81%, at least about 82%, at least about 83%, at least about 84%, at least about 85%, at least about 86%, at least about 87%, at least about 88%, at least about 89%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or 100% identical to any one of the sequences disclosed herein (e.g. about 60%, or about 61%, or about 62%, or about 63%, or about 64%, or about 65%, or about 66%, or about 67%, or about 68%, or about 69%, or about 70%, or about 71%, or about 72%, or about 73%, or about 74%, or about 75%, or about 76%, or about 77%, or about 78%, or about 79%, or about 80%, or about 81%, or about 82%, or about 83%, or about 84%, or about 85%, or about 86%, or about 87%, or about 88%, or about 89%, or about 90%, or about 91%, or about 92%, or about 93%, or about 94%, or about 95%, or about 96%, or about 97%, or about 98%, about 99% or about 100% sequence identity to any one of the sequences disclosed herein. 
     In various embodiments, the CD8 binding agent comprises a targeting moiety comprising an amino acid sequence having one or more amino acid mutations with respect to any one of the sequences disclosed herein. In various embodiments, the CD8 binding agent comprises a targeting moiety comprising an amino acid sequence having one, or two, or three, or four, or five, or six, or seen, or eight, or nine, or ten, or fifteen, or twenty amino acid mutations with respect to any one of the sequences disclosed herein. In some embodiments, the one or more amino acid mutations may be independently selected from substitutions, insertions, deletions, and truncations. 
     In some embodiments, the amino acid mutations are amino acid substitutions, and may include conservative and/or non-conservative substitutions. 
     “Conservative substitutions” may be made, for instance, on the basis of similarity in polarity, charge, size, solubility, hydrophobicity, hydrophilicity, and/or the amphipathic nature of the amino acid residues involved. The 20 naturally occurring amino acids can be grouped into the following six standard amino acid groups: (1) hydrophobic: Met, Ala, Val, Leu, lie; (2) neutral hydrophilic: Cys, Ser, Thr; Asn, Gln; (3) acidic: Asp, Glu; (4) basic: His, Lys, Arg; (5) residues that influence chain orientation: Gly, Pro; and (6) aromatic: Trp, Tyr, Phe. 
     As used herein, “conservative substitutions” are defined as exchanges of an amino acid by another amino acid listed within the same group of the six standard amino acid groups shown above. For example, the exchange of Asp by Glu retains one negative charge in the so modified polypeptide. In addition, glycine and proline may be substituted for one another based on their ability to disrupt α-helices. 
     As used herein, “non-conservative substitutions” are defined as exchanges of an amino acid by another amino acid listed in a different group of the six standard amino acid groups (1) to (6) shown above. 
     In various embodiments, the substitutions may also include non-classical amino acids (e.g. selenocysteine, pyrrolysine, N-formylmethionine β-alanine, GABA and δ-Aminolevulinic acid, 4-aminobenzoic acid (PABA), D-isomers of the common amino acids, 2,4-diaminobutyric acid, α-amino isobutyric acid, 4-aminobutyric acid, Abu, 2-amino butyric acid, γ-Abu, ε-Ahx, 6-amino hexanoic acid, Aib, 2-amino isobutyric acid, 3-amino propionic acid, ornithine, norleucine, norvaline, hydroxyproline, sarcosme, citrulline, homocitrulline, cysteic acid, t-butylglycine, t-butylalanine, phenylglycine, cyclohexylalanine, β-alanine, fluoro-amino acids, designer amino acids such as β methyl amino acids, C α-methyl amino acids, N α-methyl amino acids, and amino acid analogs in general). 
     In various embodiments, the amino acid mutation may be in the CDRs of the targeting moiety (e.g., the CDR1, CDR2 or CDR3 regions). In another embodiment, amino acid alteration may be in the framework regions (FRs) of the targeting moiety (e.g., the FR1, FR2, FR3, or FR4 regions). 
     Modification of the amino acid sequences may be achieved using any known technique in the art e.g., site-directed mutagenesis or PCR based mutagenesis. Such techniques are described, for example, in Sambrook et al., Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Press, Plainview, N.Y., 1989 and Ausubel et al., Current Protocols in Molecular Biology, John Wiley &amp; Sons, New York, N.Y., 1989. 
     In various embodiments, the mutations do not substantially reduce the present CD8 binding agent&#39;s capability to specifically bind to CD8. In various embodiments, the mutations do not substantially reduce the present CD8 binding agent&#39;s capability to specifically bind to CD8 without functionally modulating CD8. 
     In various embodiments, the binding affinity of the CD8 binding agent of the invention for the full-length and/or mature forms and/or isoforms and/or splice variants and/or fragments and/or any other naturally occurring or synthetic analogs, variants, or mutants (including monomeric, dimeric, heterodimeric, multimeric and/or associated forms) of human CD8 α and/or β chains may be described by the equilibrium dissociation constant (K D ). In various embodiments, the CD8 binding agent comprises a targeting moiety that binds to the full-length and/or mature forms and/or isoforms and/or splice variants and/or fragments and/or any other naturally occurring or synthetic analogs, variants, or mutants (including monomeric, dimeric, heterodimeric, multimeric and/or associated forms) of human CD8 α and/or β chains with a K D  of less than about 1 uM, about 900 nM, about 800 nM, about 700 nM, about 600 nM, about 500 nM, about 400 nM, about 300 nM, about 200 nM, about 100 nM, about 90 nM, about 80 nM, about 70 nM, about 60 nM, about 50 nM, about 40 nM, about 30 nM, about 20 nM, about 10 nM, or about 5 nM, or about 1 nM. 
     In various embodiments, the CD8 binding agent comprises a targeting moiety that binds but does not functionally modulate the antigen of interest, i.e., CD8. For instance, in various embodiments, the targeting moiety of the CD8 binding agent simply targets the antigen but does not substantially functionally modulate the antigen, e.g. it does not substantially inhibit, reduce or neutralize a biological effect that the antigen has. In various embodiments, the targeting moiety of the CD8 binding agent binds an epitope that is physically separate from an antigen site that is important for its biological activity (e.g. an antigen&#39;s active site). 
     Such non-functionally modulating (e.g. non-neutralizing) binding finds use in various embodiments of the present invention, including methods in which the present CD8 binding agent is used to directly or indirectly recruit active immune cells to a site of need via an effector antigen. For example, in various embodiments, the present CD8 binding agent may be used to directly or indirectly recruit cytotoxic T cells via CD8 to a tumor cell in a method of reducing or eliminating a tumor (e.g. the CD8 binding agent may comprise a targeting moiety having an anti-CD8 antigen recognition domain and a targeting moiety having a recognition domain (e.g. an antigen recognition domain) directed against a tumor antigen or receptor). In such embodiments, it is desirable to directly or indirectly recruit CD8-expressing cytotoxic T cells but not to neutralize the CD8 activity. In these embodiments, CD8 signaling is an important piece of the tumor reducing or eliminating effect. 
     Therapeutic Agents Comprising the Present CD8 Binding Agents 
     Chimeras and Fusions with Signaling Agents 
     In various embodiments, the CD8 binding agent of the invention is part of a chimera or fusion with one or more signaling agents. Accordingly, the present invention provides for chimeric or fusion proteins that include, for example, a targeting moiety against CD8 and one or more signaling agents. 
     In various embodiments, the signaling agent is modified to have reduced affinity or activity for one or more of its receptors, which allows for attenuation of activity (inclusive of agonism or antagonism) and/or prevents non-specific signaling or undesirable sequestration of the chimeric or fusion protein. In various embodiments, the signaling agent is antagonistic in its wild type form and bears one or more mutations that attenuate its antagonistic activity. 
     In various embodiments, the signaling agent is antagonistic due to one or more mutations, e.g. an agonistic signaling agent is converted to an antagonistic signaling agent and, such a converted signaling agent, optionally, also bears one or more mutations that attenuate its antagonistic activity (e.g. as described in WO 2015/007520, the entire contents of which are hereby incorporated by reference). 
     Accordingly, in various embodiments, the signaling agent is a modified (e.g. mutant) form of the signaling agent having one or more modifications (e.g. mutations). In various embodiments, the mutations allow for the modified signaling agent to have one or more of attenuated activity such as one or more of reduced binding affinity, reduced endogenous activity, and reduced specific bioactivity relative to unmutated, i.e. the wild type form of the signaling agent (e.g. comparing the same signaling agent in a wild type form versus a modified (e.g. mutant) form). In some embodiments, the mutations which attenuate or reduce binding or affinity include those mutations which substantially reduce or ablate binding or activity. In some embodiments, the mutations which attenuate or reduce binding or affinity are different than those mutations which substantially reduce or ablate binding or activity. Consequentially, in various embodiments, the mutations allow for the signaling agent to have improved safety, e.g. reduced systemic toxicity, reduced side effects, and reduced off-target effects relative to unmutated, i.e. wild type, signaling agent (e.g. comparing the same signaling agent in a wild type form versus a modified (e.g. mutant) form). 
     As described herein, the agent may have improved safety due to one of more modifications, e.g. mutations. In various embodiments, improved safety means that the present chimeric protein provides lower toxicity (e.g. systemic toxicity and/or tissue/organ-associated toxicities); and/or lessened or substantially eliminated side effects; and/or increased tolerability, lessened or substantially eliminated adverse events; and/or reduced or substantially eliminated off-target effects; and/or an increased therapeutic window. 
     In various embodiments, the signaling agent is modified to have one or more mutations that reduce its binding affinity or activity for one or more of its receptors. In some embodiments, the signaling agent is modified to have one or more mutations that substantially reduce or ablate binding affinity or activity for the receptors. In some embodiments, the activity provided by the wild type signaling agent is agonism at the receptor (e.g. activation of a cellular effect at a site of therapy). For example, the wild type signaling agent may activate its receptor. In such embodiments, the mutations result in the modified signaling agent to have reduced or ablated activating activity at the receptor. For example, the mutations may result in the modified signaling agent to deliver a reduced activating signal to a target cell or the activating signal could be ablated. In some embodiments, the activity provided by the wild type signaling agent is antagonism at the receptor (e.g. blocking or dampening of a cellular effect at a site of therapy). For example, the wild type signaling agent may antagonize or inhibit the receptor. In these embodiments, the mutations result in the modified signaling agent to have a reduced or ablated antagonizing activity at the receptor. For example, the mutations may result in the modified signaling agent to deliver a reduced inhibitory signal to a target cell or the inhibitory signal could be ablated. In various embodiments, the signaling agent is antagonistic due to one or more mutations, e.g. an agonistic signaling agent is converted to an antagonistic signaling agent (e.g. as described in WO 2015/007520, the entire contents of which are hereby incorporated by reference) and, such a converted signaling agent, optionally, also bears one or mutations that reduce its binding affinity or activity for one or more of its receptors or that substantially reduce or ablate binding affinity or activity for one or more of its receptors. 
     In some embodiments, the reduced affinity or activity at the receptor is restorable by attachment with one or more of the targeting moieties as described herein (e.g., targeting moiety against CD8). In other embodiments, the reduced affinity or activity at the receptor is not substantially restorable by the activity of one or more of the targeting moieties. 
     In various embodiments, the chimeric proteins of the present invention reduce off-target effects because their signaling agents have mutations that weaken or ablate binding affinity or activity at a receptor. In various embodiments, this reduction in side effects is observed relative with, for example, the wild type signaling agents. In various embodiments, the signaling agent is active on target cells because the targeting moiety(ies) compensates for the missing/insufficient binding (e.g., without limitation and/or avidity) required for substantial activation. In various embodiments, the modified signaling agent is substantially inactive en route to the site of therapeutic activity and has its effect substantially on specifically targeted cell types which greatly reduces undesired side effects. 
     In some embodiments, the signaling agent may include one or more mutations that attenuate or reduce binding or affinity for one receptor (i.e., a therapeutic receptor) and one or more mutations that substantially reduce or ablate binding or activity at a second receptor. In such embodiments, these mutations may be at the same or at different positions (i.e., the same mutation or multiple mutations). In some embodiments, the mutation(s) that reduce binding and/or activity at one receptor is different than the mutation(s) that substantially reduce or ablate at another receptor. In some embodiments, the mutation(s) that reduce binding and/or activity at one receptor is the same as the mutation(s) that substantially reduce or ablate at another receptor. In some embodiments, the present chimeric proteins have a modified signaling agent that has both mutations that attenuate binding and/or activity at a therapeutic receptor and therefore allow for a more controlled, on-target therapeutic effect (e.g. relative wild type signaling agent) and mutations that substantially reduce or ablate binding and/or activity at another receptor and therefore reduce side effects (e.g. relative to wild type signaling agent). 
     In some embodiments, the substantial reduction or ablation of binding or activity is not substantially restorable with a targeting moiety (e.g., a targeting moiety against CD8 or any other targeting moiety described herein). In some embodiments, the substantial reduction or ablation of binding or activity is restorable with a targeting moiety. In various embodiments, substantially reducing or ablating binding or activity at a second receptor also may prevent deleterious effects that are mediated by the other receptor. Alternatively, or in addition, substantially reducing or ablating binding or activity at the other receptor causes the therapeutic effect to improve as there is a reduced or eliminated sequestration of the therapeutic chimeric proteins away from the site of therapeutic action. For instance, in some embodiments, this obviates the need of high doses of the present chimeric proteins that compensate for loss at the other receptor. Such ability to reduce dose further provides a lower likelihood of side effects. 
     In various embodiments, the modified signaling agent comprises one or more mutations that cause the signaling agent to have reduced, substantially reduced, or ablated affinity, e.g. binding (e.g. K D ) and/or activation (for instance, when the modified signaling agent is an agonist of its receptor, measurable as, for example, K A  and/or EC 50 ) and/or inhibition (for instance, when the modified signaling agent is an antagonist of its receptor, measurable as, for example, K I  and/or IC 50 ), for one or more of its receptors. In various embodiments, the reduced affinity at the immumodulating agent&#39;s receptor allows for attenuation of activity (inclusive of agonism or antagonism). In such embodiments, the modified signaling agent has about 1%, or about 3%, about 5%, about 10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, or about 10%-20%, about 20%-40%, about 50%, about 40%-60%, about 60%-80%, about 80%-100% of the affinity for the receptor relative to the wild type signaling agent. In some embodiments, the binding affinity is at least about 2-fold lower, about 3-fold lower, about 4-fold lower, about 5-fold lower, about 6-fold lower, about 7-fold lower, about 8-fold lower, about 9-fold lower, at least about 10-fold lower, at least about 15-fold lower, at least about 20-fold lower, at least about 25-fold lower, at least about 30-fold lower, at least about 35-fold lower, at least about 40-fold lower, at least about 45-fold lower, at least about 50-fold lower, at least about 100-fold lower, at least about 150-fold lower, or about 10-50-fold lower, about 50-100-fold lower, about 100-150-fold lower, about 150-200-fold lower, or more than 200-fold lower relative to the wild type signaling agent. 
     In embodiments wherein the modified signaling agent has mutations that reduce binding at one receptor and substantially reduce or ablate binding at a second receptor, the attenuation or reduction in binding affinity of a modified signaling agent for one receptor is less than the substantial reduction or ablation in affinity for the other receptor. In some embodiments, the attenuation or reduction in binding affinity of a modified signaling agent for one receptor is less than the substantial reduction or ablation in affinity for the other receptor by about 1%, or about 3%, about 5%, about 10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, or about 95%. In various embodiments, substantial reduction or ablation refers to a greater reduction in binding affinity and/or activity than attenuation or reduction. 
     In various embodiments, the modified signaling agent comprises one or more mutations that reduce the endogenous activity of the signaling agent to about 75%, or about 70%, or about 60%, or about 50%, or about 40%, or about 30%, or about 25%, or about 20%, or about 10%, or about 5%, or about 3%, or about 1%, e.g., relative to the wild type signaling agent. 
     In some embodiments, the modified signaling agent comprises one or more mutations that cause the signaling agent to have reduced affinity for its receptor that is lower than the binding affinity of the targeting moiety(ies) for its(their) receptor(s). In some embodiments, this binding affinity differential is between signaling agent/receptor and targeting moiety/receptor on the same cell. In some embodiments, this binding affinity differential allows for the signaling agent, e.g. mutated signaling agent, to have localized, on-target effects and to minimize off-target effects that underlie side effects that are observed with wild type signaling agent. In some embodiments, this binding affinity is at least about 2-fold, or at least about 5-fold, or at least about 10-fold, or at least about 15-fold lower, or at least about 25-fold, or at least about 50-fold lower, or at least about 100-fold, or at least about 150-fold. 
     Receptor binding activity may be measured using methods known in the art. For example, affinity and/or binding activity may be assessed by Scatchard plot analysis and computer-fitting of binding data (e.g. Scatchard, 1949) or by reflectometric interference spectroscopy under flow through conditions, as described by Brecht et al. (1993), the entire contents of all of which are hereby incorporated by reference. 
     In various embodiments, the signaling agent is an immune-modulating agent, e.g. one or more of an interleukin, interferon, and tumor necrosis factor. 
     In some embodiments, the signaling agent is an interleukin or a modified interleukin, including for example IL-1; IL-2; IL-3; IL-4; IL-5; IL-6; IL-7; IL-8; IL-9; IL-10; IL-11; IL-12; IL-13; IL-14; IL-15; IL-16; IL-17; IL-18; IL-19; IL- 20; IL-21; IL-22; IL-23; IL-24; IL-25; IL-26; IL-27; IL-28; IL-29; IL-30; IL-31; IL-32; IL-33; IL-35; IL-36 or a fragment, variant, analogue, or family-member thereof. Interleukins are a group of multi-functional cytokines synthesized by lymphocytes, monocytes, and macrophages. Known functions include stimulating proliferation of immune cells (e.g., T helper cells, B cells, eosinophils, and lymphocytes), chemotaxis of neutrophils and T lymphocytes, and/or inhibition of interferons. Interleukin activity can be determined using assays known in the art: Matthews et al., in  Lymphokines and Interferens: A Practical Approach , Clemens et al., eds, IRL Press, Washington, D.C. 1987, pp. 221-225; and Orencole &amp; Dinarello (1989) Cytokine 1, 14-20. 
     In some embodiments, the signaling agent is an interferon or a modified version of an interferon such as interferon types I, II, and III. Illustrative interferons, including for example, interferon-α-1, 2, 4, 5, 6, 7, 8, 10, 13, 14, 16, 17, and 21, interferon-β and interferon-γ, interferon κ, interferon ε, interferon τ, and interferon  ω . 
     In some embodiments, the signaling agent is a tumor necrosis factor (TNF) or a modified version of a tumor necrosis factor (TNF) or a protein in the TNF family, including but not limited to, TNF-α, TNF-β, LT-β, CD40L, CD27L, CD30L, FASL, 4-1BBL, OX40L, and TRAIL. 
     The amino acid sequences of the wild type signaling agents described herein are well known in the art. Accordingly, in various embodiments the modified signaling agent comprises an amino acid sequence that has at least about 60%, or at least about 61%, or at least about 62%, or at least about 63%, or at least about 64%, or at least about 65%, or at least about 66%, or at least about 67%, or at least about 68%, or at least about 69%, or at least about 70%, or at least about 71%, or at least about 72%, or at least about 73%, or at least about 74%, or at least about 75%, or at least about 76%, or at least about 77%, or at least about 78%, or at least about 79%, or at least about 80%, or at least about 81%, or at least about 82%, or at least about 83%, or at least about 84%, or at least about 85%, or at least about 86%, or at least about 87%, or at least about 88%, or at least about 89%, or at least about 90%, or at least about 91%, or at least about 92%, or at least about 93%, or at least about 94%, or at least about 95%, or at least about 96%, or at least about 97%, or at least about 98%, or at least about 99% sequence identity with the known wild type amino acid sequences of the signaling agents described herein (e.g. about 60%, or about 61%, or about 62%, or about 63%, or about 64%, or about 65%, or about 66%, or about 67%, or about 68%, or about 69%, or about 70%, or about 71%, or about 72%, or about 73%, or about 74%, or about 75%, or about 76%, or about 77%, or about 78%, or about 79%, or about 80%, or about 81%, or about 82%, or about 83%, or about 84%, or about 85%, or about 86%, or about 87%, or about 88%, or about 89%, or about 90%, or about 91%, or about 92%, or about 93%, or about 94%, or about 95%, or about 96%, or about 97%, or about 98%, or about 99% sequence identity). 
     In various embodiments the modified signaling agent comprises an amino acid sequence that has at least about 60%, or at least about 61%, or at least about 62%, or at least about 63%, or at least about 64%, or at least about 65%, or at least about 66%, or at least about 67%, or at least about 68%, or at least about 69%, or at least about 70%, or at least about 71%, or at least about 72%, or at least about 73%, or at least about 74%, or at least about 75%, or at least about 76%, or at least about 77%, or at least about 78%, or at least about 79%, or at least about 80%, or at least about 81%, or at least about 82%, or at least about 83%, or at least about 84%, or at least about 85%, or at least about 86%, or at least about 87%, or at least about 88%, or at least about 89%, or at least about 90%, or at least about 91%, or at least about 92%, or at least about 93%, or at least about 94%, or at least about 95%, or at least about 96%, or at least about 97%, or at least about 98%, or at least about 99% sequence identity with any amino acid sequences of the signaling agents described herein (e.g. about 60%, or about 61%, or about 62%, or about 63%, or about 64%, or about 65%, or about 66%, or about 67%, or about 68%, or about 69%, or about 70%, or about 71%, or about 72%, or about 73%, or about 74%, or about 75%, or about 76%, or about 77%, or about 78%, or about 79%, or about 80%, or about 81%, or about 82%, or about 83%, or about 84%, or about 85%, or about 86%, or about 87%, or about 88%, or about 89%, or about 90%, or about 91%, or about 92%, or about 93%, or about 94%, or about 95%, or about 96%, or about 97%, or about 98%, or about 99% sequence identity). 
     In various embodiments, the modified signaling agent comprises an amino acid sequence having one or more amino acid mutations. In some embodiments, the one or more amino acid mutations may be independently selected from substitutions, insertions, deletions, and truncations. In some embodiments, the amino acid mutations are amino acid substitutions, and may include conservative and/or non-conservative substitutions, as described elsewhere herein. In various embodiments, the substitutions may also include non-classical amino acids as described elsewhere herein. 
     As described herein, the modified signaling agents bear mutations that affect affinity and/or activity at one or more receptors. In various embodiments, there is reduced affinity and/or activity at a therapeutic receptor, e.g. a receptor through which a desired therapeutic effect is mediated (e.g. agonism or antagonism). In various embodiments, the modified signaling agents bear mutations that substantially reduce or ablate affinity and/or activity at a receptor, e.g. a receptor through which a desired therapeutic effect is not mediated (e.g. as the result of promiscuity of binding). The receptors of any modified signaling agents, e.g. one of the cytokines, growth factors, and hormones as described herein, are known in the art. 
     Illustrative mutations which provide reduced affinity and/or activity (e.g. agonistic) at a receptor are found in WO 2013/107791 and PCT/EP2017/061544 (e.g. with regard to interferons), WO 2015/007542 (e.g. with regard to interleukins), and WO 2015/007903 (e.g. with regard to TNF), the entire contents of each of which are hereby incorporated by reference. Illustrative mutations which provide reduced affinity and/or activity (e.g. antagonistic) at a therapeutic receptor are found in WO 2015/007520, the entire contents of which are hereby incorporated by reference. 
     In some embodiments, the modified signaling agent comprises one or more mutations that cause the signaling agent to have reduced affinity and/or activity for a type I cytokine receptor, a type II cytokine receptor, a chemokine receptor, a receptor in the Tumor Necrosis Factor Receptor (TNFR) superfamily, TGF-beta Receptors, a receptor in the immunoglobulin (Ig) superfamily, and/or a receptor in the tyrosine kinase superfamily. 
     In various embodiments, the receptor for the signaling agent is a Type I cytokine receptor. Type I cytokine receptors are known in the art and include, but are not limited to receptors for IL2 (beta-subunit), IL3, IL4, IL5, IL6, IL7, IL9, IL11, IL12, GM-CSF, G-CSF, LIF, CNTF, and also the receptors for Thrombopoietin (TPO), Prolactin, and Growth hormone. Illustrative type I cytokine receptors include, but are not limited to, GM-CSF receptor, G-CSF receptor, LIF receptor, CNTF receptor, TPO receptor, and type I IL receptors. 
     In various embodiments, the receptor for the signaling agent is a Type II cytokine receptor. Type II cytokine receptors are multimeric receptors composed of heterologous subunits, and are receptors mainly for interferons. This family of receptors includes, but is not limited to, receptors for interferon-α, interferon-β and interferon-γ, IL10, IL22, and tissue factor. Illustrative type II cytokine receptors include, but are not limited to, IFN-α receptor (e.g. IFNAR1 and IFNAR2), IFN-β receptor, IFN-γ receptor (e.g. IFNGR1 and IFNGR2), and type II IL receptors. 
     In various embodiments, the receptor for the signaling agent is a G protein-coupled receptor. Chemokine receptors are G protein-coupled receptors with seven transmembrane structure and coupled to G-protein for signal transduction. Chemokine receptors include, but are not limited to, CC chemokine receptors, CXC chemokine receptors, CX3C chemokine receptors, and XC chemokine receptor (XCR1). Exemplary chemokine receptors include, but are not limited to, CCR1, CCR2, CCR3, CCR4, CCR5, CCR6, CCR7, CCR8, CCR9, CCR10, CXCR1, CXCR2, CXCR3, CXCR3B, CXCR4, CXCR5, CSCR6, CXCR7, XCR1, and CX3CR1. 
     In various embodiments, the receptor for the signaling agent is a TNFR family member. Tumor necrosis factor receptor (TNFR) family members share a cysteine-rich domain (CRD) formed of three disulfide bonds surrounding a core motif of CXXCXXC creating an elongated molecule. Exemplary tumor necrosis factor receptor family members include: CDI 20a (TNFRSFIA), CD 120b (TNFRSFIB), Lymphotoxin beta receptor (LTBR, TNFRSF3), CD 134 (TNFRSF4), CD40 (CD40, TNFRSF5), FAS (FAS, TNFRSF6), TNFRSF6B (TNFRSF6B), CD27 (CD27, TNFRSF7), CD30 (TNFRSF8), CD137 (TNFRSF9), TNFRSFIOA (TNFRSFIOA), TNFRSFIOB, (TNFRSFIOB), TNFRSFIOC (TNFRSFIOC), TNFRSFIOD (TNFRSFIOD), RANK (TNFRSFI IA), Osteoprotegerin (TNFRSFI IB), TNFRSF12A (TNFRSF12A), TNFRSF13B (TNFRSF13B), TNFRSF13C (TNFRSF13C), TNFRSF14 (TNFRSF14), Nerve growth factor receptor (NGFR, TNFRSF16), TNFRSF17 (TNFRSF17), TNFRSF18 (TNFRSF18), TNFRSF19 (TNFRSF19), TNFRSF21 (TNFRSF21), and TNFRSF25 (TNFRSF25). In an embodiment, the TNFR family member is CD120a (TNFRSF1A) or TNF-R1. In another embodiment, the TNFR family member is CD 120b (TNFRSFIB) or TNF-R2. 
     In various embodiments, the receptor for the signaling agent is a TGF-beta receptor. TGF-beta receptors are single pass serine/threonine kinase receptors. TGF-beta receptors include, but are not limited to, TGFBR1, TGFBR2, and TGFBR3. 
     In various embodiments, the receptor for the signaling agent is an Ig superfamily receptor. Receptors in the immunoglobulin (Ig) superfamily share structural homology with immunoglobulins. Receptors in the Ig superfamily include, but are not limited to, interleukin-1 receptors, CSF-1R, PDGFR (e.g. PDGFRA and PDGFRB), and SCFR. 
     In various embodiments, the receptor for the signaling agent is a tyrosine kinase superfamily receptor. Receptors in the tyrosine kinase superfamily are well known in the art. There are about 58 known receptor tyrosine kinases (RTKs), grouped into 20 subfamilies. Receptors in the tyrosine kinase superfamily include, but are not limited to, FGF receptors and their various isoforms such as FGFR1, FGFR2, FGFR3, FGFR4, and FGFR5. 
     In an embodiment, the modified signaling agent is interferon α. In such embodiments, the modified IFN-α agent has reduced affinity and/or activity for the IFN-α/β receptor (IFNAR), i.e., IFNAR1 and/or IFNAR2 chains. In some embodiments, the modified IFN-α agent has substantially reduced or ablated affinity and/or activity for the IFN-α/β receptor (IFNAR), i.e., IFNAR1 and/or IFNAR2 chains. 
     Mutant forms of interferon α are known to the person skilled in the art. In an illustrative embodiment, the modified signaling agent is the allelic form IFN-α2a having the amino acid sequence of IFN-α2a (SEQ ID NO:288). 
     In an illustrative embodiment, the modified signaling agent is the allelic form IFN-α2b having the amino acid sequence of (which differs from IFN-α2a at amino acid position 23) IFN-α2b (SEQ ID NO:289). 
     In some embodiments, said IFN-α2 mutant (IFN-α2a or IFN-α2b) is mutated atone or more amino acids at positions 144-154, such as amino acid positions 148, 149 and/or 153. In some embodiments, the IFN-α2 mutant comprises one or more mutations selected from L153A, R149A, and M148A. Such mutants are described, for example, in WO2013/107791 and Piehler et al., (2000) J. Biol. Chem, 275:40425-33, the entire contents of all of which are hereby incorporated by reference. 
     In some embodiments, the IFN-α2 mutants have reduced affinity and/or activity for IFNAR1. In some embodiments, the IFN-α2 mutant comprises one or more mutations selected from F64A, N65A, T69A, L80A, Y85A, and Y89A, as described in WO2010/030671, the entire contents of which is hereby incorporated by reference. 
     In some embodiments, the IFN-α2 mutant comprises one or more mutations selected from K133A, R144A, R149A, and L153A as described in WO2008/124086, the entire contents of which is hereby incorporated by reference. 
     In some embodiments, the IFN-α2 mutant comprises one or more mutations selected from R120E and R120E/K121E, as described in WO2015/007520 and WO2010/030671, the entire contents of which are hereby incorporated by reference. In such embodiments, said IFN-α2 mutant antagonizes wild type IFN-α2 activity. In such embodiments, said mutant IFN-α2 has reduced affinity and/or activity for IFNAR1 while affinity and/or activity of IFNR2 is retained. 
     In some embodiments, the human IFN-α2 mutant comprises (1) one or more mutations selected from R120E and R120E/K121E, which, without wishing to be bound by theory, create an antagonistic effect and (2) one or more mutations selected from K133A, R144A, R149A, and L153A, which, without wishing to be bound by theory, allow for an attenuated effect at, for example, IFNAR2. In an embodiment, the human IFN-α2 mutant comprises R120E and L153A. 
     In some embodiments, the human IFN-α2 mutant comprises one or more mutations selected from, L15A, A19W, R22A, R23A, L26A, F27A, L30A, L30V, K31A, D32A, R33K, R33A, R33Q, H34A, D35A, Q40A, D114R, L117A, R120A, R125A, K134A, R144A, A145G, A145M, M148A, R149A, S152A, L153A, and N156A as disclosed in WO 2013/059885, the entire disclosures of which are hereby incorporated by reference. In some embodiments, the human IFN-α2 mutant comprises the mutations H57Y, E58N, Q61S, and/or L30A as disclosed in WO 2013/059885. In some embodiments, the human IFN-α2 mutant comprises the mutations H57Y, E58N, Q61S, and/or R33A as disclosed in WO 2013/059885. In some embodiments, the human IFN-α2 mutant comprises the mutations H57Y, E58N, Q61S, and/or M148A as disclosed in WO 2013/059885. In some embodiments, the human IFN-α2 mutant comprises the mutations H57Y, E58N, Q61S, and/or L153A as disclosed in WO 2013/059885. In some embodiments, the human IFN-α2 mutant comprises the mutations N65A, L80A, Y85A, and/or Y89A as disclosed in WO 2013/059885. In some embodiments, the human IFN-α2 mutant comprises the mutations N65A, L80A, Y85A, Y89A, and/or D114A as disclosed in WO 2013/059885. 
     In an embodiment, the modified signaling agent is interferon β. In such embodiments, the modified interferon β agent has reduced affinity and/or activity for the IFN-α/β receptor (IFNAR), i.e., IFNAR1 and/or IFNAR2 chains. In some embodiments, the modified interferon β agent has substantially reduced or ablated affinity and/or activity for the IFN-α/β receptor (IFNAR), i.e., IFNAR1 and/or IFNAR2 chains. 
     In an illustrative embodiment, the modified signaling agent is IFN-β. In various embodiments, the IFN-β encompasses functional derivatives, analogs, precursors, isoforms, splice variants, or fragments of IFN-β. In various embodiments, the IFN-β encompasses IFN-β derived from any species. In an embodiment, the chimeric protein comprises a modified version of mouse IFN-β. In another embodiment, the chimeric protein comprises a modified version of human IFN-β. Human IFN-β is a polypeptide with a molecular weight of about 22 kDa comprising 166 amino acid residues. The amino acid sequence of human IFN-β is SEQ ID NO:290. 
     In some embodiments, the human IFN-β is IFN-β-1a which is a glycosylated form of human IFN-β. In some embodiments, the human IFN-β is IFN-β-1b which is a non-glycosylated form of human IFN-β that has a Met-1 deletion and a Cys-17 to Ser mutation. 
     In various embodiments, the modified IFN-β has one or more mutations that reduce its binding to or its affinity for the IFNAR1 subunit of IFNAR. In one embodiment, the modified IFN-β has reduced affinity and/or activity at IFNAR1. In various embodiments, the modified IFN-β is human IFN-β and has one or more mutations at positions F67, R71, L88, Y92, 195, N96, K123, and R124. In some embodiments, the one or more mutations are substitutions selected from F67G, F67S, R71A, L88G, L88S, Y92G, Y92S, I95A, N96G, K123G, and R124G. In an embodiment, the modified IFN-β comprises the F67G mutation. In an embodiment, the modified IFN-β comprises the K123G mutation. In an embodiment, the modified IFN-β comprises the F67G and R71A mutations. In an embodiment, the modified IFN-β comprises the L88G and Y92G mutations. In an embodiment, the modified IFN-β comprises the Y92G, I95A, and N96G mutations. In an embodiment, the modified IFN-β comprises the K123G and R124G mutations. In an embodiment, the modified IFN-β comprises the F67G, L88G, and Y92G mutations. In an embodiment, the modified IFN-β comprises the F67S, L88S, and Y92S mutations. 
     In some embodiments, the modified IFN-β has one or more mutations that reduce its binding to or its affinity for the IFNAR2 subunit of IFNAR. In one embodiment, the modified IFN-β has reduced affinity and/or activity at IFNAR2. In various embodiments, the modified IFN-β is human IFN-β and has one or more mutations at positions W22, R27, L32, R35, V148, L151, R152, and Y155. In some embodiments, the one or more mutations are substitutions selected from W22G, R27G, L32A, L32G, R35A, R35G, V148G, L151G, R152A, R152G, and Y155G. 
     In an embodiment, the modified IFN-β comprises the W22G mutation. In an embodiment, the modified IFN-β comprises the L32A mutation. In an embodiment, the modified IFN-β comprises the L32G mutation. In an embodiment, the modified IFN-β comprises the R35A mutation. In an embodiment, the modified IFN-β comprises the R35G mutation. In an embodiment, the modified IFN-β comprises the V148G mutation. In an embodiment, the modified IFN-β comprises the R152A mutation. In an embodiment, the modified IFN-β comprises the R152G mutation. In an embodiment, the modified IFN-β comprises the Y155G mutation. In an embodiment, the modified IFN-β comprises the W22G and R27G mutations. In an embodiment, the modified IFN-β comprises the L32A and R35A mutation. In an embodiment, the modified IFN-β comprises the L151G and R152A mutations. In an embodiment, the modified IFN-β comprises the V148G and R152A mutations. 
     In some embodiments, the modified IFN-β has one or more of the following mutations: R35A, R35T, E42K, M621, G78S, A141Y, A142T, E149K, and R152H. In some embodiments, the modified IFN-β has one or more of the following mutations: R35A, R35T, E42K, M621, G78S, A141Y, A142T, E149K, and R152H in combination with C17S or C17A. 
     In some embodiments, the modified IFN-β has one or more of the following mutations: R35A, R35T, E42K, M621, G78S, A141Y, A142T, E149K, and R152H in combination with any of the other IFN-β mutations described herein. 
     The crystal structure of human IFN-β is known and is described in Karpusas et al., (1998) PNAS, 94(22): 11813-11818. Specifically, the structure of human IFN-β has been shown to include five α-helices (i.e., A, B, C, D, and E) and four loop regions that connect these helices (i.e., AB, BC, CD, and DE loops). In various embodiments, the modified IFN-β has one or more mutations in the A, B, C, D, E helices and/or the AB, BC, CD, and DE loops which reduce its binding affinity or activity at a therapeutic receptor such as IFNAR. Exemplary mutations are described in WO2000/023114 and US20150011732, the entire contents of which are hereby incorporated by reference. In an exemplary embodiment, the modified IFN-β is human IFN-β comprising alanine substitutions at amino acid positions 15, 16, 18, 19, 22, and/or 23. In an exemplary embodiment, the modified IFN-β is human IFN-β comprising alanine substitutions at amino acid positions 28-30, 32, and 33. In an exemplary embodiment, the modified IFN-β is human IFN-β comprising alanine substitutions at amino acid positions 36, 37, 39, and 42. In an exemplary embodiment, the modified IFN-β is human IFN-β comprising alanine substitutions at amino acid positions 64 and 67 and a serine substitution at position 68. In an exemplary embodiment, the modified IFN-β is human IFN-β comprising alanine substitutions at amino acid positions 71-73. In an exemplary embodiment, the modified IFN-β is human IFN-β comprising alanine substitutions at amino acid positions 92, 96, 99, and 100. In an exemplary embodiment, the modified IFN-β is human IFN-β comprising alanine substitutions at amino acid positions 128, 130, 131, and 134. In an exemplary embodiment, the modified IFN-β is human IFN-β comprising alanine substitutions at amino acid positions 149, 153, 156, and 159. In some embodiments, the mutant IFNβ comprises SEQ ID NO: 290 and a mutation at W22, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), leucine (L), isoleucine (I), methionine (M), and valine (V). 
     In some embodiments, the mutant IFNβ comprises SEQ ID NO:290 and a mutation at R27, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), leucine (L), isoleucine (I), methionine (M), and valine (V). 
     In some embodiments, the mutant IFNβ comprises SEQ ID NO:290 and a mutation at W22, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), leucine (L), isoleucine (I), methionine (M), and valine (V) and a mutation at R27, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), leucine (L), isoleucine (I), methionine (M), and valine (V). 
     In some embodiments, the mutant IFNβ comprises SEQ ID NO:290 and a mutation at L32, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), isoleucine (I), methionine (M), and valine (V). 
     In some embodiments, the mutant IFNβ comprises SEQ ID NO:290 and a mutation at R35, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), leucine (L), isoleucine (I), methionine (M), and valine (V). 
     In some embodiments, the mutant IFNβ comprises SEQ ID NO:290 and a mutation at L32, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), isoleucine (I), methionine (M), and valine (V) and a mutation at R35, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), leucine (L), isoleucine (I), methionine (M), and valine (V). 
     In some embodiments, the mutant IFNβ comprises SEQ ID NO:290 and a mutation at F67, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), leucine (L), isoleucine (I), methionine (M), and valine (V). 
     In some embodiments, the mutant IFNβ comprises SEQ ID NO:290 and a mutation at R71, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), leucine (L), isoleucine (I), methionine (M), and valine (V). 
     In some embodiments, the mutant IFNβ comprises SEQ ID NO:290 and a mutation at F67, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), leucine (L), isoleucine (I), methionine (M), and valine (V) and a mutation at R71, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), leucine (L), isoleucine (I), methionine (M), and valine (V). 
     In some embodiments, the mutant IFNβ comprises SEQ ID NO:290 and a mutation at L88, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), isoleucine (I), methionine (M), and valine (V). 
     In some embodiments, the mutant IFNβ comprises SEQ ID NO:290 and a mutation at Y92, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), leucine (L), isoleucine (I), methionine (M), and valine (V). 
     In some embodiments, the mutant IFNβ comprises SEQ ID NO:290 and a mutation at F67, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), leucine (L), isoleucine (I), methionine (M), and valine (V) and a mutation at L88, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), isoleucine (I), methionine (M), and valine (V) and a mutation at Y92, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), leucine (L), isoleucine (I), methionine (M), and valine (V). 
     In some embodiments, the mutant IFNβ comprises SEQ ID NO:290 and a mutation at L88, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), isoleucine (I), methionine (M), and valine (V) and a mutation at Y92, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), leucine (L), isoleucine (I), methionine (M), and valine (V). 
     In some embodiments, the mutant IFNβ comprises SEQ ID NO:290 and a mutation at I95, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), leucine (L), methionine (M), and valine (V) and a mutation at Y92, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), leucine (L), isoleucine (I), methionine (M), and valine (V). 
     In some embodiments, the mutant IFNβ comprises SEQ ID NO:290 and a mutation at N96, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), leucine (L), isoleucine (I), methionine (M), and valine (V) and a mutation at Y92, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), leucine (L), isoleucine (I), methionine (M), and valine (V). 
     In some embodiments, the mutant IFNβ comprises SEQ ID NO:290 and a mutation at Y92, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), leucine (L), isoleucine (I), methionine (M), and valine (V) and a mutation at I95, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), leucine (L), methionine (M), and valine (V) and a mutation at N96, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), leucine (L), isoleucine (I), methionine (M), and valine (V). 
     In some embodiments, the mutant IFNβ comprises SEQ ID NO:290 and a mutation at K123, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), leucine (L), isoleucine (I), methionine (M), and valine (V). 
     In some embodiments, the mutant IFNβ comprises SEQ ID NO:290 and a mutation at R124, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), leucine (L), isoleucine (I), methionine (M), and valine (V). 
     In some embodiments, the mutant IFNβ comprises SEQ ID NO:290 and a mutation at K123, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), leucine (L), isoleucine (I), methionine (M), and valine (V) and a mutation at R124, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), leucine (L), isoleucine (I), methionine (M), and valine (V). 
     In some embodiments, the mutant IFNβ comprises SEQ ID NO:290 and a mutation at L151, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), isoleucine (I), methionine (M), and valine (V). 
     In some embodiments, the mutant IFNβ comprises SEQ ID NO:290 and a mutation at R152, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), leucine (L), isoleucine (I), methionine (M), and valine (V). 
     In some embodiments, the mutant IFNβ comprises SEQ ID NO:290 and a mutation at L151, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), isoleucine (I), methionine (M), and valine (V) and a mutation at R152, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), leucine (L), isoleucine (I), methionine (M), and valine (V). 
     In some embodiments, the mutant IFNβ comprises SEQ ID NO:290 and a mutation at V148, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), leucine (L), isoleucine (I), and methionine (M). 
     In some embodiments, the mutant IFNβ comprises SEQ ID NO:290 and a mutation at V148, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), leucine (L), isoleucine (I), methionine (M), and valine (V) and a mutation at R152, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), leucine (L), isoleucine (I), methionine (M), and valine (V). 
     In some embodiments, the mutant IFNβ comprises SEQ ID NO:290 and a mutation at Y155, the mutation being an aliphatic hydrophobic residue selected from glycine (G), alanine (A), leucine (L), isoleucine (I), methionine (M), and valine (V). 
     In some embodiments, the present invention relates to a chimeric protein comprising: (a) a modified IFN-β, having the amino acid sequence of SEQ ID NO:290 and a mutation at position W22, wherein the mutation is an aliphatic hydrophobic residue; and (b) one or more targeting moieties, said targeting moieties comprising recognition domains which specifically bind to antigens or receptors of interest (e.g., CD8), the modified IFN-β and the one or more targeting moieties are optionally connected with one or more linkers. In various embodiments the mutation at position W22 is aliphatic hydrophobic residue is selected from G, A, L, I, M, and V. In various embodiments the mutation at position W22 is G. 
     Additional exemplary IFNβ mutants are provided in PCT/EP2017/061544, the entire disclosure of which is incorporated by reference herein. 
     In an embodiment, the modified signaling agent is interferon γ. In such embodiments, the modified interferon γ agent has reduced affinity and/or activity for the interferon-gamma receptor (IFNGR), i.e., IFNGR1 and IFNGR2 chains. In some embodiments, the modified interferon γ agent has substantially reduced or ablated affinity and/or activity for the interferon-gamma receptor (IFNGR), i.e., IFNGR1 and/or IFNGR2 chains. 
     In some embodiments, the modified signaling agent is vascular endothelial growth factor (VEGF). VEGF is a potent growth factor that plays major roles in physiological but also pathological angiogenesis, regulates vascular permeability and can act as a growth factor on cells expressing VEGF receptors. Additional functions include, among others, stimulation of cell migration in macrophage lineage and endothelial cells. Several members of the VEGF family of growth factors exist, as well as at least three receptors (VEGFR-1, VEGFR-2, and VEGFR-3). 
     Members of the VEGF family can bind and activate more than one VEGFR type. For example, VEGF-A binds VEGFR-1 and -2, while VEGF-C can bind VEGFR-2 and -3. VEGFR-1 and -2 activation regulates angiogenesis while VEGFR-3 activation is associated with lymphangiogenesis. The major pro-angiogenic signal is generated from activation of VEGFR-2. VEGFR-1 activation has been reported to be possibly associated with negative role in angiogenesis. It has also been reported that VEGFR-1 signaling is important for progression of tumors in vivo via bone marrow-derived VEGFR-1 positive cells (contributing to formation of premetastatic niche in the bone). Several therapies based on VEGF-A directed/neutralizing therapeutic antibodies have been developed, primarily for use in treatment of various human tumors relying on angiogenesis. These are not without side effects though. This may not be surprising considering that these operate as general, non-cell/tissue specific VEGF/VEGFR interaction inhibitors. Hence, it would be desirable to restrict VEGF (e.g. VEGF-A)/VEGFR-2 inhibition to specific target cells (e.g. tumor vasculature endothelial cells). 
     In some embodiments, the VEGF is VEGF-A, VEGF-B, VEFG-C, VEGF-D, or VEGF-E and isoforms thereof including the various isoforms of VEGF-A such as VEGF 121 , VEGF 121 b, VEGF 145 , VEGF 165 , VEGF 16 b, VEGF 189 , and VEGF 206 . In some embodiments, the modified signaling agent has reduced affinity and/or activity for VEGFR-1 (Flt-1) and/or VEGFR-2 (KDR/Flk-1). In some embodiments, the modified signaling agent has substantially reduced or ablated affinity and/or activity for VEGFR-1 (Flt-1) and/or VEGFR-2 (KDR/Flk-1). In an embodiment, the modified signaling agent has reduced affinity and/or activity for VEGFR-2 (KDR/Flk-1) and/or substantially reduced or ablated affinity and/or activity for VEGFR-1 (Flt-1). Such an embodiment finds use, for example, in wound healing methods or treatment of ischmia-related diseases (without wishing to be bound by theory, mediated by VEGFR-2&#39;s effects on endothelial cell function and angiogenesis). In various embodiments, binding to VEGFR-1 (Flt-1), which is linked to cancers and pro-inflammatory activities, is avoided. In various embodiments, VEGFR-1 (Flt-1) acts a decoy receptor and therefore substantially reduces or ablates affinity at this receptor avoids sequestration of the therapeutic agent. In an embodiment, the modified signaling agent has substantially reduced or ablated affinity and/or activity for VEGFR-1 (Flt-1) and/or substantially reduced or ablated affinity and/or activity for VEGFR-2 (KDR/Flk-1). In some embodiments, the VEGF is VEGF-C or VEGF-D. In such embodiments, the modified signaling agent has reduced affinity and/or activity for VEGFR-3. Alternatively, the modified signaling agent has substantially reduced or ablated affinity and/or activity for VEGFR-3. 
     Proangiogenic therapies are also important in various diseases (e.g. ischemic heart disease, bleeding etc.), and include VEGF-based therapeutics. Activation of VEGFR-2 is proangiogenic (acting on endothelial cells). Activation of VEFGR-1 can cause stimulation of migration of inflammatory cells (including, for example, macrophages) and lead to inflammation associated hypervascular permeability. Activation of VEFGR-1 can also promote bone marrow associated tumor niche formation. Thus, VEGF based therapeutic selective for VEGFR-2 activation would be desirable in this case. In addition, cell specific targeting, e.g. to endothelial cells, would be desirable. 
     In some embodiments, the modified signaling agent has reduced affinity and/or activity (e.g. antagonistic) for VEGFR-2 and/or has substantially reduced or ablated affinity and/or activity for VEGFR-1. When targeted to tumor vasculature endothelial cells via a targeting moiety that binds to a tumor endothelial cell marker (e.g. PSMA and others), such construct inhibits VEGFR-2 activation specifically on such marker-positive cells, while not activating VEGFR-1 en route and on target cells (if activity ablated), thus eliminating induction of inflammatory responses, for example. This would provide a more selective and safe anti-angiogenic therapy for many tumor types as compared to VEGF-A neutralizing therapies. 
     In some embodiments, the modified signaling agent has reduced affinity and/or activity (e.g. agonistic) for VEGFR-2 and/or has substantially reduced or ablated affinity and/or activity for VEGFR-1. Through targeting to vascular endothelial cells, such construct, in some embodiments, promotes angiogenesis without causing VEGFR-1 associated induction of inflammatory responses. Hence, such a construct would have targeted proangiogenic effects with substantially reduced risk of side effects caused by systemic activation of VEGFR-2 as well as VEGR-1. 
     In an illustrative embodiment, the modified signaling agent is VEGF 165 , which has the amino acid sequence SEQ ID NO:291. 
     In another illustrative embodiment, the modified signaling agent is VEGF 165b , which has the amino acid sequence SEQ ID NO:292. 
     In these embodiments, the modified signaling agent has a mutation at amino acid 183 (e.g., a substitution mutation at I83, e.g., I83K, I83R, or I83H). Without wishing to be bound by theory, it is believed that such mutations may result in reduced receptor binding affinity. See, for example, U.S. Pat. No. 9,078,860, the entire contents of which are hereby incorporated by reference. 
     In an embodiment, the modified signaling agent is TNF-α. TNF is a pleiotropic cytokine with many diverse functions, including regulation of cell growth, differentiation, apoptosis, tumorigenesis, viral replication, autoimmunity, immune cell functions and trafficking, inflammation, and septic shock. It binds to two distinct membrane receptors on target cells: TNFR1 (p55) and TNFR2 (p75). TNFR1 exhibits a very broad expression pattern whereas TNFR2 is expressed preferentially on certain populations of lymphocytes, Tregs, endothelial cells, certain neurons, microglia, cardiac myocytes and mesenchymal stem cells. Very distinct biological pathways are activated in response to receptor activation, although there is also some overlap. As a general rule, without wishing to be bound by theory, TNFR1 signaling is associated with induction of apoptosis (cell death) and TNFR2 signaling is associated with activation of cell survival signals (e.g. activation of NFkB pathway). Administration of TNF is systemically toxic, and this is largely due to TNFR1 engagement. However, it should be noted that activation of TNFR2 is also associated with a broad range of activities and, as with TNFR1, in the context of developing TNF based therapeutics, control over TNF targeting and activity is important. 
     In some embodiments, the modified signaling agent has reduced affinity and/or activity for TNFR1 and/or TNFR2. 
     In some embodiments, the modified signaling agent has substantially reduced or ablated affinity and/or activity for TNFR1 and/or TNFR2. TNFR1 is expressed in most tissues, and is involved in cell death signaling while, by contrast, TNFR2 is involved in cell survival signaling. Accordingly, in embodiments directed to methods of treating cancer, the modified signaling agent has reduced affinity and/or activity for TNFR1 and/or substantially reduced or ablated affinity and/or activity for TNFR2. In these embodiments, the chimeric proteins may be targeted to a cell for which apoptosis is desired, e.g. a tumor cell or a tumor vasculature endothelial cell. In embodiments directed to methods of promoting cell survival, for example, in neurogenesis for the treatment of neurodegenerative disorders, the modified signaling agent has reduced affinity and/or activity for TNFR2 and/or substantially reduced or ablated affinity and/or activity for TNFR1. Stated another way, the present chimeric proteins, in some embodiments, comprise modified TNF-α agent that allows of favoring either death or survival signals. 
     In some embodiments, the chimeric protein has a modified TNF having reduced affinity and/or activity for TNFR1 and/or substantially reduced or ablated affinity and/or activity for TNFR2. Such a chimera, in some embodiments, is a more potent inducer of apoptosis as compared to a wild type TNF and/or a chimera bearing only mutation(s) causing reduced affinity and/or activity for TNFR1. Such a chimera, in some embodiments, finds use in inducing tumor cell death or a tumor vasculature endothelial cell death (e.g. in the treatment of cancers). Also, in some embodiments, these chimeras avoid or reduce activation of T reg  cells via TNFR2, for example, thus further supporting TNFR1-mediated antitumor activity in vivo. 
     In some embodiments, the chimeric protein has a modified TNF having reduced affinity and/or activity for TNFR2 and/or substantially reduced or ablated affinity and/or activity for TNFR1. Such a chimera, in some embodiments, is a more potent activator of cell survival in some cell types, which may be a specific therapeutic objective in various disease settings, including without limitation, stimulation of neurogenesis. In addition, such a TNFR2-favoring chimeras also are useful in the treatment of autoimmune diseases (e.g. Crohn&#39;s, diabetes, MS, colitis etc. and many others described herein). In some embodiments, the chimera is targeted to auto-reactive T cells. In some embodiments, the chimera promotes T reg  cell activation and indirect suppression of cytotoxic T cells. 
     In some embodiments, the chimera causes the death of auto-reactive T cells, e.g. by activation of TNFR2 and/or avoidance of TNFR1 (e.g. a modified TNF having reduced affinity and/or activity for TNFR2 and/or substantially reduced or ablated affinity and/or activity for TNFR1). Without wishing to be bound by theory these auto-reactive T cells, have their apoptosis/survival signals altered e.g. by NFkB pathway activity/signaling alterations. In some embodiments, the chimera causes the death of autoreactive T cells having lesions or modifications in the NFkB pathway, which underlie an imbalance of their cell death (apoptosis)/survival signaling properties and, optionally, altered susceptibility to certain death-inducing signals (e.g., TNFR2 activation). 
     In some embodiments, a TNFR2 based chimera has additional therapeutic applications in diseases, including various autoimmune diseases, heart disease, de-myelinating and neurodegenerative disorders, and infectious disease, among others. 
     In an embodiment, the wild type TNF-α has the amino acid sequence of SEQ ID NO:293. 
     In such embodiments, the modified TNF-α agent has mutations at one or more amino acid positions 29, 31, 32, 84, 85, 86, 87, 88, 89, 145, 146 and 147 which produces a modified TNF-α with reduced receptor binding affinity. See, for example, U.S. Pat. No. 7,993,636, the entire contents of which are hereby incorporated by reference. 
     In some embodiments, the modified human TNF-α moiety has mutations at one or more amino acid positions R32, N34, Q67, H73, L75, T77, S86, Y87, V91, 197, T105, P106, A109, P113, Y115, E127, N137, D143, A145, and E146 as described, for example, in WO/2015/007903, the entire contents of which is hereby incorporated by reference (numbering according to the human TNF sequence, Genbank accession number BAG70306, version BAG70306.1 GI: 197692685). In some embodiments, the modified human TNF-α moiety has substitution mutations selected from L29S, R32G, R32W, N34G, Q67G, H73G, L75G, L75A, L75S, T77A, S86G, S86T, Y87Q, Y87L, Y87A, Y87F, Y87H, V91G, V91A, I97A, I97Q, I97S, T105G, P106G, A109Y, P113G, Y115G, Y115A, E127G, N137G, D143N, A145G, A145R, A145T, E146D, E146K, and S147D. In an embodiment, the human TNF-α moiety has a mutation selected from Y87Q, Y87L, Y87A, Y87F, and Y87H. In another embodiment, the human TNF-α moiety has a mutation selected from I97A, I97Q, and I97S. In a further embodiment, the human TNF-α moiety has a mutation selected from Y115A and Y115G. In an embodiment, the human TNF-α moiety has an E146K mutation. In an embodiment, the human TNF-α moiety has an Y87H and an E146K mutation. In an embodiment, the human TNF-α moiety has an Y87H and an A145R mutation. In an embodiment, the human TNF-α moiety has a R32W and a S86T mutation. In an embodiment, the human TNF-α moiety has a R32W and an E146K mutation. In an embodiment, the human TNF-α moiety has a L29S and a R32W mutation. In an embodiment, the human TNF-α moiety has a D143N and an A145R mutation. In an embodiment, the human TNF-α moiety has a D143N and an A145R mutation. In an embodiment, the human TNF-α moiety has an A145T, an E146D, and a S147D mutation. In an embodiment, the human TNF-α moiety has an A145T and a S147D mutation. 
     In some embodiments, the modified TNF-α agent has one or more mutations selected from N39Y, S147Y, and Y87H, as described in WO2008/124086, the entire contents of which is hereby incorporated by reference. 
     In some embodiments, the modified human TNF-α moiety has mutations that provide receptor selectivity as described in PCT/IB2016/001668, the entire contents of which are hereby incorporated by reference. In some embodiments, the mutations to TNF are TNF-R1 selective. In some embodiments, the mutations to TNF which are TNF-R1 selective are at one or more of positions R32, S86, and E146. In some embodiments, the mutations to TNF which are TNF-R1 selective are one or more of R32W, S86T, and E146K. In some embodiments, the mutations to TNF which are TNF-R1 selective are one or more of R32W, R32W/S86T, R32W/E146K and E146K. In some embodiments, the mutations to TNF are TNF-R2 selective. In some embodiments, the mutations to TNF which are TNF-R2 selective are at one or more of positions A145, E146, and S147. In some embodiments, the mutations to TNF which are TNF-R2 selective are one or more of A145T, A145R, E146D, and S147D. In some embodiments, the mutations to TNF which are TNF-R2 selective are one or more of A145R, A145T/S147D, and A145T/E146D/S147D. 
     In an embodiment, the modified signaling agent is TNF-β. TNF-β can form a homotrimer or a heterotrimer with LT-β (LT-α1β2). In some embodiments, the modified signaling agent has substantially reduced or ablated affinity and/or activity for TNFR1 and/or TNFR2 and/or herpes virus entry mediator (HEVM) and/or LT-βR. 
     In an embodiment, the wild type TNF-β has the amino acid sequence of TNF-beta SEQ ID NO:294. 
     In such embodiments, the modified soluble agent may comprise mutations at one or more amino acids at positions 106-113, which produce a modified TNF-β with reduced receptor binding affinity to TNFR2. In an embodiment, the modified soluble agent has one or more substitution mutations at amino acid positions 106-113. In illustrative embodiments, the substitution mutations are selected from Q107E, Q107D, S106E, S106D, Q107R, Q107N, Q107E/S106E, Q107E/S106D, Q107D/S106E, and Q107D/S106D. In another embodiment, the modified soluble agent has an insertion of about 1 to about 3 amino acids at positions 106-113. 
     In some embodiments, the modified agent is a TNF family member (e.g. TNF-alpha, TNF-beta) which can be a single chain trimeric version as described in WO 2015/007903, the entire contents of which are incorporated by reference. 
     In some embodiments, the modified agent is a TNF family member (e.g. TNF-alpha, TNF-beta) which has reduced affinity and/or activity, i.e. antagonistic activity (e.g. natural antagonistic activity or antagonistic activity that is the result of one or more mutations, see, e.g., WO 2015/007520, the entire contents of which are hereby incorporated by reference) at TNFR1. In these embodiments, the modified agent is a TNF family member (e.g. TNF-alpha, TNF-beta) which also, optionally, has substantially reduced or ablated affinity and/or activity for TNFR2. In some embodiments, the modified agent is a TNF family member (e.g. TNF-alpha, TNF-beta) which has reduced affinity and/or activity, i.e. antagonistic activity (e.g. natural antagonistic activity or antagonistic activity that is the result of one or more mutations, see, e.g., WO 2015/007520, the entire contents of which are hereby incorporated by reference) at TNFR2. In these embodiments, the modified agent is a TNF family member (e.g. TNF-alpha, TNF-beta) which also, optionally, has substantially reduced or ablated affinity and/or activity for TNFR1. The constructs of such embodiments find use in, for example, methods of dampening TNF response in a cell specific manner. In some embodiments, the antagonistic TNF family member (e.g. TNF-alpha, TNF-beta) is a single chain trimeric version as described in WO 2015/007903. 
     In an embodiment, the modified signaling agent is TRAIL. In some embodiments, the modified TRAIL agent has reduced affinity and/or activity for DR4 (TRAIL-RI) and/or DR5 (TRAIL-RII) and/or DcR1 and/or DcR2. In some embodiments, the modified TRAIL agent has substantially reduced or ablated affinity and/or activity for DR4 (TRAIL-RI) and/or DR5 (TRAIL-RII) and/or DcR1 and/or DcR2. 
     In an embodiment, the wild type TRAIL has the amino acid sequence of TRAIL SEQ ID NO:295. 
     In such embodiments, the modified TRAIL agent may comprise a mutation at amino acid positions T127-R132, E144-R149, E155-H161, Y189-Y209, T214-1220, K224-A226, W231, E236-L239, E249-K251, T261-H264 and H270-E271 (Numbering based on the human sequence, Genbank accession number NP 003801, version 10 NP_003801.1, GI: 4507593; see above). 
     In some embodiments, the modified TRAIL agent may comprise one or more mutations that sustantially reduce its affinity and/or activity for TRAIL-R1. In such embodiments, the modified TRAIL agent may specifically bind to TRIL-R2. Exemplary mutations include mutations at one or more amino acid positions Y189, R191, Q193, H264, I266, and D267. For example the mutations may be one or more of Y189Q, R191K, Q193R, H264R, I266L and D267Q. 
     In an embodiment, the modified TRAIL agent comprises the mutations Y189Q, R191K, Q193R, H264R, I266L and D267Q. 
     In some embodiments, the modified TRAIL agent may comprise one or more mutations that substantially reduce its affinity and/or activity for TRAIL-R2. In such embodiments, the modified TRAIL agent may specifically bind to TRIL-R1. Exemplary mutations include mutations at one or more amino acid positions G131, R149, S159, N199, K201, and S215. For example, the mutations may be one or more of G131R, R1491, S159R, N199R, K201H, and S215D. In an embodiment, the modified TRAIL agent comprises the mutations G131R, R1491, S159R, N199R, K201H, and S215D. Additional TRAIL mutations are described in, for example, Trebing et al., (2014) Cell Death and Disease, 5:e1035, the entire disclosure of which is hereby incorporated by reference. 
     In an embodiment, the modified signaling agent is TGFα. In such embodiments, the modified TGFα agent has reduced affinity and/or activity for the epidermal growth factor receptor (EGFR). In some embodiments, the modified TGFα agent has substantially reduced or ablated affinity and/or activity for the epidermal growth factor receptor (EGFR). 
     In an embodiment, the modified signaling agent is TGFβ. In such embodiments, the modified signaling agent has reduced affinity and/or activity for TGFBR1 and/or TGFBR2. In some embodiments, the modified signaling agent has substantially reduced or ablated affinity and/or activity for TGFBR1 and/or TGFBR2. In some embodiments, the modified signaling agent optionally has reduced or substantially reduced or ablated affinity and/or activity for TGFBR3 which, without wishing to be bound by theory, may act as a reservoir of ligand for TGF-beta receptors. In some embodiments, the TGFβ may favor TGFBR1 over TGFBR2 or TGFBR2 over TGFBR1. Similarly, LAP, without wishing to be bound by theory, may act as a reservoir of ligand for TGF-beta receptors. In some embodiments, the modified signaling agent has reduced affinity and/or activity for TGFBR1 and/or TGFBR2 and/or substantially reduced or ablated affinity and/or activity for Latency Associated Peptide (LAP). In some embodiments, such chimeras find use in Camurati-Engelmann disease, or other diseases associated with inappropriate TGFβ signaling. 
     In some embodiments, the modified agent is a TGF family member (e.g. TGFα, TGFβ) which has reduced affinity and/or activity, i.e. antagonistic activity (e.g. natural antagonistic activity or antagonistic activity that is the result of one or more mutations, see, e.g., WO 2015/007520, the entire contents of which are hereby incorporated by reference) at one or more of TGFBR1, TGFBR2, TGFBR3. In these embodiments, the modified agent is a TGF family member (e.g. TGFα, TGFβ) which also, optionally, has substantially reduced or ablated affinity and/or activity at one or more of TGFBR1, TGFBR2, TGFBR3. 
     In some embodiments, the modified agent is a TGF family member (e.g. TGFα, TGFβ) which has reduced affinity and/or activity, i.e. antagonistic activity (e.g. natural antagonistic activity or antagonistic activity that is the result of one or more mutations, see, e.g., WO 2015/007520, the entire contents of which are hereby incorporated by reference) at TGFBR1 and/or TGFBR2. In these embodiments, the modified agent is a TGF family member (e.g. TGFα, TGFβ) which also, optionally, has substantially reduced or ablated affinity and/or activity at TGFBR3. 
     In an embodiment, the modified signaling agent is an interleukin. In an embodiment, the modified signaling agent is IL-1. In an embodiment, the modified signaling agent is IL-1a or IL-1p. In some embodiments, the modified signaling agent has reduced affinity and/or activity for IL-1R1 and/or IL-1RAcP. In some embodiments, the modified signaling agent has substantially reduced or ablated affinity and/or activity for IL-1R1 and/or IL-1RAcP. In some embodiments, the modified signaling agent has reduced affinity and/or activity for IL-1R2. In some embodiments, the modified signaling agent has substantially reduced or ablated affinity and/or activity for IL-1R2. For instance, in some embodiments, the present modified IL-1 agents avoid interaction at IL-1R2 and therefore substantially reduce its function as a decoy and/or sink for therapeutic agents. 
     In an embodiment, the wild type IL-1β has the amino acid sequence of SEQ ID NO:296. 
     IL1 is a proinflammatory cytokine and an important immune system regulator. It is a potent activator of CD4 T cell responses, increases proportion of Th17 cells and expansion of IFNγ and IL-4 producing cells. IL-1 is also a potent regulator of CD8 +  T cells, enhancing antigen-specific CD8 +  T cell expansion, differentiation, migration to periphery and memory. IL-1 receptors comprise IL-1R1 and IL-1R2. Binding to and signaling through the IL-1R1 constitutes the mechanism whereby IL-1 mediates many of its biological (and pathological) activities. IL1-R2 can function as a decoy receptor, thereby reducing IL-1 availability for interaction and signaling through the IL-1R1. 
     In some embodiments, the modified IL-1 has reduced affinity and/or activity (e.g. agonistic activity) for IL-1R1. In some embodiments, the modified IL-1 has substantially reduced or ablated affinity and/or activity for IL-1R2. In such embodiments, there is restorable IL-1/IL-1R1 signaling and prevention of loss of therapeutic chimeras at IL-R2 and therefore a reduction in dose of IL-1 that is required (e.g. relative to wild type or a chimera bearing only an attenuation mutation for IL-R1). Such constructs find use in, for example, methods of treating cancer, including, for example, stimulating the immune system to mount an anti-cancer response. 
     In some embodiments, the modified IL-1 has reduced affinity and/or activity (e.g. antagonistic activity, e.g. natural antagonistic activity or antagonistic activity that is the result of one or more mutations, see, e.g., WO 2015/007520, the entire contents of which are hereby incorporated by reference) for IL-1R1. In some embodiments, the modified IL-1 has substantially reduced or ablated affinity and/or activity for IL-1R2. In such embodiments, there is the IL-1/IL-1R1 signaling is not restorable and prevention of loss of therapeutic chimeras at IL-R2 and therefore a reduction in dose of IL-1 that is required (e.g. relative to wild type or a chimera bearing only an attenuation mutation for IL-R1). Such constructs find use in, for example, methods of treating autoimmune diseases, including, for example, suppressing the immune system. 
     In such embodiments, the modified signaling agent has a deletion of amino acids 52-54 which produces a modified human IL-1β with reduced binding affinity for type I IL-1R and reduced biological activity. See, for example, WO 1994/000491, the entire contents of which are hereby incorporated by reference. In some embodiments, the modified human IL-1β has one or more substitution mutations selected from A117G/P118G, R120X, L122A, T125G/L126G, R127G, Q130X, Q131G, K132A, S137G/Q138Y, L145G, H146X, L145A/L147A, Q148X, Q148G/Q150G, Q150G/D151A, M152G, F162A, F162A/Q164E, F166A, Q164E/E167K, N169G/D170G, I172A, V174A, K208E, K209X, K209A/K210A, K219X, E221X, E221 S/N224A, N224S/K225S, E244K, N245Q (where X can be any change in amino acid, e.g., a non-conservative change), which exhibit reduced binding to IL-1R, as described, for example, in WO2015/007542 and WO/2015/007536, the entire contents of which is hereby incorporated by reference (numbering base on the human IL-1β sequence, Genbank accession number NP_000567, version NP-000567.1, GI: 10835145). In some embodiments, the modified human IL-1β may have one or more mutations selected from R120A, R120G, Q130A, Q130W, H146A, H146G, H146E, H146N, H146R, Q148E, Q148G, Q148L, K209A, K209D, K219S, K219Q, E221S and E221K. In an embodiment, the modified human IL-1β comprises the mutations Q131G and Q148G. In an embodiment, the modified human IL-1β comprises the mutations Q148G and K208E. In an embodiment, the modified human IL-1β comprises the mutations R120G and Q131G. In an embodiment, the modified human IL-1β comprises the mutations R120G and H146A. In an embodiment, the modified human IL-1β comprises the mutations R120G and H146N. In an embodiment, the modified human IL-1β comprises the mutations R120G and H146R. In an embodiment, the modified human IL-1p comprises the mutations R120G and H146E. In an embodiment, the modified human IL-1β comprises the mutations R120G and H146G. In an embodiment, the modified human IL-1β comprises the mutations R120G and K208E. In an embodiment, the modified human IL-1β comprises the mutations R120G, F162A, and Q164E. 
     In an embodiment, the modified signaling agent is IL-2. In such an embodiment, the modified signaling agent has reduced affinity and/or activity for IL-2Rα and/or IL-2Rβ and/or IL-2Rγ. In some embodiments, the modified signaling agent has reduced affinity and/or activity for IL-2Rβ and/or IL-2Rγ. In some embodiments, the modified signaling agent has substantially reduced or ablated affinity and/or activity for IL-2Rα. Such embodiments may be relevant for treatment of cancer, for instance when the modified IL-2 is agonistic at IL-2Rβ and/or IL-2Rγ. For instance, the present constructs may favor attenuated activation of CD8 +  T cells (which can provide an anti-tumor effect), which have IL2 receptors β and γ and disfavor T regs  (which can provide an immune suppressive, pro-tumor effect), which have IL2 receptors α, β, and γ. Further, in some embodiments, the preferences for IL-2Rβ and/or IL-2Rγ over IL-2Rα avoid IL-2 side effects such as pulmonary edema. Also, IL-2-based chimeras are useful for the treatment of autoimmune diseases, for instance when the modified IL-2 is antagonistic (e.g. natural antagonistic activity or antagonistic activity that is the result of one or more mutations, see, e.g., WO 2015/007520, the entire contents of which are hereby incorporated by reference) at IL-2Rβ and/or IL-2Rγ. For instance, the present constructs may favor attenuated suppression of CD8 +  T cells (and therefore dampen the immune response), which have IL2 receptors β and γ and disfavor T regs  which have IL2 receptors α, β, and γ. Alternatively, in some embodiments, the chimeras bearing IL-2 favor the activation of T regs , and therefore immune suppression, and activation of disfavor of CD8 +  T cells. For instance, these constructs find use in the treatment of diseases or diseases that would benefit from immune suppression, e.g. autoimmune disorders. 
     In some embodiments, the chimeric protein has targeting moieties as described herein directed to CD8 +  T cells as well as a modified IL-2 agent having reduced affinity and/or activity for IL-2Rβ and/or IL-2Rγ and/or substantially reduced or ablated affinity and/or activity for IL-2Rα. In some embodiments, these constructs provide targeted CD8 +  T cell activity and are generally inactive (or have substantially reduced activity) towards T reg  cells. In some embodiments, such constructs have enhanced immune stimulatory effect compared to wild type IL-2 (e.g., without wishing to be bound by theory, by not stimulating Tregs), whilst eliminating or reducing the systemic toxicity associated with IL-2. 
     In an embodiment, the wild type IL-2 has the amino acid sequence of SEQ ID NO:297. 
     In such embodiments, the modified IL-2 agent has one or more mutations at amino acids L72 (L72G, L72A, L72S, L72T, L72Q, L72E, L72N, L72D, L72R, or L72K), F42 (F42A, F42G, F42S, F42T, F42Q, F42E, F42N, F42D, F42R, or F42K) and Y45 (Y45A, Y45G, Y45S, Y45T, Y45Q, Y45E, Y45N, Y45D, Y45R or Y45K). Without wishing to be bound by theory, it is believed that these modified IL-2 agents have reduced affinity for the high-affinity IL-2 receptor and preserves affinity to the intermediate-affinity IL-2 receptor, as compared to the wild-type IL-2. See, for example, US Patent Publication No. 2012/0244112, the entire contents of which are hereby incorporated by reference. 
     In some embodiments, the modified IL-2 agent has one or more mutations at amino acids R38, F42, Y45, and E62. 
     For example, the modified IL-2 agent may comprise one or more of R38A, F42A, Y45A, and E62A. In some embodiments, the modified IL-2 agent may comprise a mutation at C125. For example, the mutation may be C125S. In such embodiments, the modified IL-2 agent may have substantially reduced affinity and/or activity for IL-2Rα, as described in, for example, Carmenate et al. (2013) The Journal of Immunology, 190:6230-6238, the entire disclosure of which is hereby incorporated by reference. In some embodiments, the modified IL-2 agent with mutations at R38, F42, Y45, and/or E62 is able to induce an expansion of effector cells including CD8 +  T cells and NK cells but not Treg cells. In some embodiments, the modified IL-2 agent with mutations at R38, F42, Y45, and/or E62 is less toxic than wildtype IL-2 agents. A chimeric protein comprising the modified IL-2 agent with substantially reduced affinity and/or activity for IL-2Rα may find application in oncology for example. 
     In other embodiments, the modified IL-2 agent may have substantially reduced affinity and/or activity for IL-2Rβ, as described in, for example, WO2016/025385, the entire disclosure of which is hereby incorporated by reference. In such embodiments, the modified IL-2 agent may induce an expansio of Treg cells but not effector cells such as CD8 +  T cells and NK cells. A chimeric protein comprising the modified IL-2 agent with substantially reduced affinity and/or activity for IL-2Rβ may find application in the treatment of autoimmune disease for example. In some embodiments, the modified IL-2 agent may comprise one or more mutations at amino acids N88, D20, and/r A126. For example, the modified IL-2 agent may comprise one or more of N88R, N881, N88G, D20H, Q126L, and Q126F. 
     In various embodiments, the modified IL-2 agent may comprise a mutation at D109 or C125. For example, the mutation may be D109C or C125S. In some embodiments, the modified IL-2 with a mutation at D109 or C125 may be utilized for attachment to a PEG moiety. 
     In an embodiment, the modified signaling agent is IL-3. In some embodiments, the modified signaling agent has reduced affinity and/or activity for the IL-3 receptor, which is a heterodimer with a unique alpha chain paired with the common beta (beta c or CD131) subunit. In some embodiments, the modified signaling agent has substantially reduced or ablated affinity and/or activity for the IL-3 receptor, which is a heterodimer with a unique alpha chain paired with the common beta (beta c or CD131) subunit. 
     In an embodiment, the modified signaling agent is IL-4. In such an embodiment, the modified signaling agent has reduced affinity and/or activity for type 1 and/or type 2 IL-4 receptors. In such an embodiment, the modified signaling agent has substantially reduced or ablated affinity and/or activity for type 1 and/or type 2 IL-4 receptors. Type 1 IL-4 receptors are composed of the IL-4Ra subunit with a common γ chain and specifically bind IL-4. Type 2 IL-4 receptors include an IL-4Ra subunit bound to a different subunit known as IL-13Rα1. In some embodiments, the modified signaling agent has substantially reduced or ablated affinity and/or activity the type 2 IL-4 receptors. 
     In an embodiment, the wild type IL-4 has the amino acid sequence of SEQ ID NO:298. 
     In such embodiments, the modified IL-4 agent has one or more mutations at amino acids R121 (R121A, R121D, R121E, R121F, R121H, R1211, R121K, R121N, R121P, R121T, R121W), E122 (E122F), Y124 (Y124A, Y124Q, Y124R, Y124S, Y124T) and S125 (S125A). Without wishing to be bound by theory, it is believed that these modified IL-4 agents maintain the activity mediated by the type I receptor, but significantly reduces the biological activity mediated by the other receptors. See, for example, U.S. Pat. No. 6,433,157, the entire contents of which are hereby incorporated by reference. 
     In an embodiment, the modified signaling agent is IL-6. IL-6 signals through a cell-surface type I cytokine receptor complex including the ligand-binding IL-6R chain (CD126), and the signal-transducing component gp130. IL-6 may also bind to a soluble form of IL-6R (sIL-6R), which is the extracellular portion of IL-6R. The sIL-6R/IL-6 complex may be involved in neurites outgrowth and survival of neurons and, hence, may be important in nerve regeneration through remyelination. Accordingly, in some embodiments, the modified signaling agent has reduced affinity and/or activity for IL-6R/gp130 and/or sIL-6R. In some embodiments, the modified signaling agent has substantially reduced or ablated affinity and/or activity for IL-6R/gp130 and/or sIL-6R. 
     In an embodiment, the wild type IL-6 has the amino acid sequence of IL-6 (mature form, wild type) (SEQ ID NO:299). 
     In such embodiments, the modified signaling agent has one or more mutations at amino acids 58, 160, 163, 171 or 177. Without wishing to be bound by theory, it is believed that these modified IL-6 agents exhibit reduced binding affinity to IL-6Ralpha and reduced biological activity. See, for example, WO 97/10338, the entire contents of which are hereby incorporated by reference. 
     In an embodiment, the modified signaling agent is IL-10. In such an embodiment, the modified signaling agent has reduced affinity and/or activity for IL-10 receptor-1 and IL-10 receptor-2. In some embodiments, the modified signaling agent has substantially reduced or ablated affinity and/or activity for IL-10 receptor-1 and IL-10 receptor-2 
     In an embodiment, the modified signaling agent is IL-11. In such an embodiment, the modified signaling agent has reduced affinity and/or activity for IL-11Rα and/or IL-11Rβ and/or gp130. In such an embodiment, the modified signaling agent has substantially reduced or ablated affinity and/or activity for IL-11Rα and/or IL-11Rβ and/or gp130. 
     In an embodiment, the modified signaling agent is IL-12. In such an embodiment, the modified signaling agent has reduced affinity and/or activity for IL-12Rβ1 and/or IL-12Rβ2. In such an embodiment, the modified signaling agent has substantially reduced or ablated affinity and/or activity for IL-12Rβ1 and/or IL-12Rβ2. 
     In an embodiment, the modified signaling agent is IL-13. In such an embodiment, the modified signaling agent has reduced affinity and/or activity for the IL-4 receptor (IL-4Ra) and IL-13Rα1. In some embodiments, the modified signaling agent has substantially reduced or ablated affinity and/or activity for IL-4 receptor (IL-4Ra) or IL-13Rα1. 
     In an embodiment, the wild type IL-13 has the amino acid sequence of IL-13 (mature form, wild type) (SEQ ID NO:300). 
     In such embodiments, the modified IL-13 agent has one or more mutations at amino acids 13, 16, 17, 66, 69, 99, 102, 104, 105, 106, 107, 108, 109, 112, 113 and 114. Without wishing to be bound by theory, it is believed that these modified IL-13 agents exhibit reduced biological activity. See, for example, WO 2002/018422, the entire contents of which are hereby incorporated by reference. 
     In an embodiment, the modified signaling agent is IL-18. In some embodiments, the modified signaling agent has reduced affinity and/or activity for IL-18Rα and/or IL-18Rβ. In some embodiments, the modified signaling agent has substantially reduced or ablated affinity and/or activity for IL-18Rα and/or IL-18Rβ. In some embodiments, the modified signaling agent has substantially reduced or ablated affinity and/or activity for IL-18Rα type II, which is an isoform of IL-18Rα that lacks the TIR domain required for signaling. 
     In an embodiment, the wild type IL-18 has the amino acid sequence of IL-18 (wild type) (SEQ ID NO:301). 
     In such embodiments, the modified IL-18 agent may comprise one or more mutations in amino acids or amino acid regions selected from Y37-K44, R49-Q54, D59-R63, E67-C74, R80, M87-A97, N 127-K129, Q139-M149, K165-K171, R183 and Q190-N191, as described in WO/2015/007542, the entire contents of which are hereby incorporated by reference (numbering based on the human IL-18 sequence, Genbank accession number AAV38697, version AAV38697.1, GI: 54696650). 
     In an embodiment, the modified signaling agent is IL-33. In such an embodiment, the modified signaling agent has reduced affinity and/or activity for the ST-2 receptor and IL-1RAcP. In some embodiments, the modified signaling agent has substantially reduced or ablated affinity and/or activity for the ST-2 receptor and IL-1RAcP. 
     In an embodiment, the wild type IL-33 has the amino acid sequence of SEQ ID NO:302. 
     In such embodiments, the modified IL-33 agent may comprise one or more mutations in amino acids or amino acid regions selected from I113-Y122, S127-E139, E144-D157, Y163-M183, E200, Q215, L220-C227 and T260-E269, as described in WO/2015/007542, the entire contents of which are hereby incorporated by reference (numbering based on the human sequence, Genbank accession number NP_254274, version NP_254274.1, GI:15559209). 
     In an embodiment, the modified signaling agent is epidermal growth factor (EGF). EGF is a member of a family of potent growth factors. Members include EGF, HB-EGF, and others such as TGF alpha, amphiregulin, neuregulins, epiregulin, betacellulin. EGF family receptors include EGFR (ErbB1), ErbB2, ErbB3 and ErbB4. These may function as homodimeric and for heterodimeric receptor subtypes. The different EGF family members exhibit differential selectivity for the various receptor subtypes. For example, EGF associates with ErbB1/ErbB1, ErbB1/ErbB2, ErbB4/ErbB2 and some other heterodimeric subtypes. HB-EGF has a similar pattern, although it also associates with ErbB4/4. Modulation of EGF (EGF-like) growth factor signaling, positively or negatively, is of considerable therapeutic interest. For example, inhibition of EGFRs signaling is of interest in the treatment of various cancers where EGFR signaling constitutes a major growth promoting signal. Alternatively, stimulation of EGFRs signaling is of therapeutic interest in, for example, promoting wound healing (acute and chronic), oral mucositis (a major side-effect of various cancer therapies, including, without limitation radiation therapy). 
     In some embodiments, the modified signaling agent has reduced affinity and/or activity for ErbB1, ErbB2, ErbB3, and/or ErbB4. Such embodiments find use, for example, in methods of treating wounds. In some embodiments, the modified signaling agent binds to one or more ErbB1, ErbB2, ErbB3, and ErbB4 and antagonizes the activity of the receptor. In such embodiments, the modified signaling agent has reduced affinity and/or activity for ErbB1, ErbB2, ErbB3, and/or ErbB4 which allows for the activity of the receptor to be antagonized in an attenuated fashion. 
     Such embodiments find use in, for example, treatments of cancer. In an embodiment, the modified signaling agent has reduced affinity and/or activity for ErbB1. ErbB1 is the therapeutic target of kinase inhibitors—most have side effects because they are not very selective (e.g., gefitinib, erlotinib, afatinib, brigatinib and icotinib). In some embodiments, attenuated antagonistic ErbB1 signaling is more on-target and has less side effects than other agents targeting receptors for EGF. 
     In some embodiments, the modified signaling agent has reduced affinity and/or activity (e.g. antagonistic e.g. natural antagonistic activity or antagonistic activity that is the result of one or more mutations, see, e.g., WO 2015/007520, the entire contents of which are hereby incorporated by reference) for ErbB1 and/or substantially reduced or ablated affinity and/or activity for ErbB4 or other subtypes it may interact with. Through specific targeting via the targeting moiety, cell-selective suppression (antagonism e.g. natural antagonistic activity or antagonistic activity that is the result of one or more mutations, see, e.g., WO 2015/007520, the entire contents of which are hereby incorporated by reference) of ErbB1/ErbB1 receptor activation would be achieved—while not engaging other receptor subtypes potentially associated with inhibition-associated side effects. Hence, in contrast to EGFR kinase inhibitors, which inhibit EGFR activity in all cell types in the body, such a construct would provide a cell-selective (e.g., tumor cell with activated EGFR signaling due to amplification of receptor, overexpression etc.) anti-EGFR (ErbB1) drug effect with reduced side effects. 
     In some embodiments, the modified signaling agent has reduced affinity and/or activity (e.g. agonistic) for ErbB4 and/or other subtypes it may interact with. Through targeting to specific target cells through the targeting moiety, a selective activation of ErbB1 signaling is achieved (e.g. epithelial cells). Such a construct finds use, in some embodiments, in the treatment of wounds (promoting would healing) with reduced side effects, especially for treatment of chronic conditions and application other than topical application of a therapeutic (e.g. systemic wound healing). 
     In an embodiment, the modified signaling agent is insulin or insulin analogs. In some embodiments, the modified insulin or insulin analog has reduced affinity and/or activity for the insulin receptor and/or IGF1 or IGF2 receptor. 
     In some embodiments, the modified insulin or insulin analog has substantially reduced or ablated affinity and/or activity for the insulin receptor and/or IGF1 or IGF2 receptor. Attenuated response at the insulin receptor allows for the control of diabetes, obesity, metabolic disorders and the like while directing away from IGF1 or IGF2 receptor avoids pro-cancer effects. 
     In an embodiment, the modified signaling agent is insulin-like growth factor-I or insulin-like growth factor-II (IGF-1 or IGF-2). In an embodiment, the modified signaling agent is IGF-1. In such an embodiment, the modified signaling agent has reduced affinity and/or activity for the insulin receptor and/or IGF1 receptor. In an embodiment, the modified signaling agent may bind to the IGF1 receptor and antagonize the activity of the receptor. In such an embodiment, the modified signaling agent has reduced affinity and/or activity for IGF1 receptor which allows for the activity of the receptor to be antagonized in an attenuated fashion. In some embodiments, the modified signaling agent has substantially reduced or ablated affinity and/or activity for the insulin receptor and/or IGF1 receptor. In some embodiments, the modified signaling agent has reduced affinity and/or activity for IGF2 receptor which allows for the activity of the receptor to be antagonized in an attenuated fashion. In an embodiment, the modified signaling agent has substantially reduced or ablated affinity and/or activity for the insulin receptor and accordingly does not interfere with insulin signaling. In various embodiments, this applies to cancer treatment. In various embodiments, the present agents may prevent IR isoform A from causing resistance to cancer treatments. 
     In one embodiment, the present chimeric protein has (i) a CD8 binding agent and (ii) a targeting moiety which is directed against a tumor cell, along with any of the modified (e.g. mutant) form signaling agents described herein. In an embodiment, the present chimeric protein has a targeting moiety directed against CD8 on T cells and a second targeting moiety directed against PD-L1 or PD-L2 on tumor cells. 
     In various embodiments, the signaling agent is a toxin or toxic enzyme. In some embodiments, the toxin or toxic enzyme is derived from plants and bacteria. Illustrative toxins or toxic enzymes include, but are not limited to, the diphtheria toxin,  Pseudomonas  toxin, anthrax toxin, ribosome-inactivating proteins (RIPs) such as ricin and saporin, modeccin, abrin, gelonin, and poke weed antiviral protein. Additional toxins include those disclosed in Mathew et al., (2009) Cancer Sci 100(8): 1359-65, the entire disclosures are hereby incorporated by reference. In such embodiments, the chimeric proteins of the invention may be utilized to induce cell death in cell-type specific manner. In such embodiments, the toxin may be modified, e.g. mutated, to reduce affinity and/or activity of the toxin for an attenuated effect, as described with other signaling agents herein. 
     Multi-Specific Chimeras and Fusions with Signaling Agents 
     In various embodiments, the CD8 binding agent of the invention is part of a chimera or fusion with one or more signaling agents as described herein and/or one or more additional targeting moieties. Accordingly, the present invention provides for chimeric or fusion proteins that include one or more signaling agents and a targeting moiety against CD8 and/or one or more additional targeting moieties. 
     In various embodiments, the CD8 binding agent of the invention is multispecific, i.e., the CD8 binding agent comprises two or more targeting moieties having recognition domains that recognize and bind two or more targets, e.g. antigens, or receptors, or epitopes. In such embodiments, the CD8 binding agent of the invention may comprise two more targeting moieties having recognition domains that recognize and bind two or more epitopes on the same antigen or on different antigens. In various embodiments, such multi-specific CD8 binding agents exhibit advantageous properties such as increased avidity and/or improved selectivity. In an embodiment, the CD8 binding agent of the invention comprises two targeting moieties and is bispecific, i.e., binds and recognizes two epitopes on the same antigen or on different antigens. 
     In various embodiments, the multispecific CD8 binding agent of the invention comprises two or more targeting moieties with each targeting moiety being an antibody or an antibody derivative as described herein. In an embodiment, the multispecific CD8 binding agent of the invention comprises at least one VHH comprising an antigen recognition domain against CD8 and one antibody or antibody derivative comprising an antigen recognition domain against a tumor antigen. 
     In various embodiments, the present multispecific CD8 binding agents have two or more targeting moieties that target different antigens or receptors, and one targeting moiety may be attenuated for its antigen or receptor, e.g. the targeting moiety binds its antigen or receptor with a low affinity or avidity (including, for example, at an affinity or avidity that is less than the affinity or avidity the other targeting moiety has for its for its antigen or receptor, for instance the difference between the binding affinities may be about 10-fold, or 25-fold, or 50-fold, or 100-fold, or 300-fold, or 500-fold, or 1000-fold, or 5000-fold; for instance the lower affinity or avidity targeting moiety may bind its antigen or receptor at a K D  in the mid- to high-nM or low- to mid-NM range while the higher affinity or avidity targeting moiety may bind its antigen or receptor at a K D  in the mid- to high-pM or low- to mid-nM range). For instance, in some embodiments, the present multispecific CD8 binding agents comprises an attenuated targeting moiety that is directed against a promiscuous antigen or receptor, which may improve targeting to a cell of interest (e.g. via the other targeting moiety) and prevent effects across multiple types of cells, including those not being targeted for therapy (e.g. by binding promiscuous antigen or receptor at a higher affinity than what is provided in these embodiments). In various embodiments, the present chimeric proteins have one or more targeting moieties that target different antigens or receptors with low affinities or avidities and can enhance binding of the other, e.g. cooperatively. 
     The multispecific CD8 binding agent of the invention may be constructed using methods known in the art, see for example, U.S. Pat. No. 9,067,991, U.S. Patent Publication No. 20110262348 and WO 2004/041862, the entire contents of which are hereby incorporated by reference. In an illustrative embodiment, the multispecific CD8 binding agent of the invention comprising two or more targeting moieties may be constructed by chemical crosslinking, for example, by reacting amino acid residues with an organic derivatizing agent as described by Blattler et al., Biochemistry 24, 1517-1524 and EP294703, the entire contents of which are hereby incorporated by reference. In another illustrative embodiment, the multispecific CD8 binding agent comprising two or more targeting moieties is constructed by genetic fusion, i.e., constructing a single polypeptide which includes the polypeptides of the individual targeting moieties. For example, a single polypeptide construct may be formed which encodes a first VHH with an antigen recognition domain against CD8 and a second antibody or antibody derivative with an antigen recognition domain against a tumor antigen. A method for producing bivalent or multivalent VHH polypeptide constructs is disclosed in PCT patent application WO 96/34103, the entire contents of which is hereby incorporated by reference. In a further illustrative embodiment, the multispecific CD8 binding agent of the invention may be constructed by using linkers. For example, the carboxy-terminus of a first VHH with an antigen recognition domain against CD8 may be linked to the amino-terminus of a second antibody or antibody derivative with an antigen recognition domain against a tumor antigen (or vice versa). Exemplary linkers that may be used are described herein. In some embodiments, the components of the multispecific CD8 binding agent of the invention are directly linked to each other without the use of linkers. 
     In various embodiments, the multi-specific CD8 binding agent of the invention recognizes and binds to CD8 and one or more antigens found on one or more immune cells, which can include, without limitation, megakaryocytes, thrombocytes, erythrocytes, mast cells, basophils, neutrophils, eosinophils, monocytes, macrophages, natural killer cells, T lymphocytes (e.g., cytotoxic T lymphocytes, T helper cells, natural killer T cells), B lymphocytes, plasma cells, dendritic cells, or subsets thereof. In some embodiments, the CD8 binding agent specifically binds to an antigen of interest and effectively directly or indirectly recruits one of more immune cells. 
     In various embodiments, the multi-specific CD8 binding agent of the invention recognizes and binds to CD8 and one or more antigens found on tumor cells. In these embodiments, the present CD8 binding agents may directly or indirectly recruit an immune cell to a tumor cell or the tumor microenvironment. In some embodiments, the present CD8 binding agents may directly or indirectly recruit an immune cell, e.g. an immune cell that can kill and/or suppress a tumor cell (e.g., a CTL), to a site of action (such as, by way of non-limiting example, the tumor microenvironment). 
     In some embodiments, the present CD8 binding agents are capable of, or find use in methods involving, shifting the balance of immune cells in favor of immune attack of a tumor. For instance, the present CD8 binding agents can shift the ratio of immune cells at a site of clinical importance in favor of cells that can kill and/or suppress a tumor (e.g. T cells, cytotoxic T lymphocytes, T helper cells, natural killer (NK) cells, natural killer T (NKT) cells, anti-tumor macrophages (e.g. M1 macrophages), neutrophils, B cells, dendritic cells or subsets thereof and in opposition to cells that protect tumors (e.g. myeloid-derived suppressor cells (MDSCs), regulatory T cells (Tregs); tumor associated neutrophils (TANs), M2 macrophages, tumor associated macrophages (TAMs), or subsets thereof). In some embodiments, the present CD8 binding agent is capable of increasing a ratio of effector T cells to regulatory T cells. 
     In some embodiments, the multi-specific CD8 binding agent of the invention comprises a targeting moiety having an antigen recognition domain that specifically binds to an antigen associated with tumor cells. In some embodiments, the targeting moiety directly or indirectly recruits tumor cells. For instance, in some embodiments, the recruitment of the tumor cell is to one or more effector cell (e.g. an immune cell as described herein) that can kill and/or suppress the tumor cell. In some embodiments, the targeting moiety directly or indirectly recruits T cells to a tumor cell, for example, by virtue of the two targeting moieties interacting with their respective antigens on a tumor and CD8-positive immune cell (e.g. T cell). 
     Tumor cells, or cancer cells refer to an uncontrolled growth of cells or tissues and/or an abnormal increased in cell survival and/or inhibition of apoptosis which interferes with the normal functioning of bodily organs and systems. 
     For example, tumor cells include benign and malignant cancers, polyps, hyperplasia, as well as dormant tumors or micrometastases. Illustrative tumor cells include, but are not limited to cells of: basal cell carcinoma, biliary tract cancer; bladder cancer; bone cancer; brain and central nervous system cancer; breast cancer; cancer of the peritoneum; cervical cancer; choriocarcinoma; colon and rectum cancer; connective tissue cancer; cancer of the digestive system; endometrial cancer; esophageal cancer; eye cancer; cancer of the head and neck; gastric cancer (including gastrointestinal cancer); glioblastoma; hepatic carcinoma; hepatoma; intra-epithelial neoplasm; kidney or renal cancer; larynx cancer; leukemia; liver cancer; lung cancer (e.g., small-cell lung cancer, non-small cell lung cancer, adenocarcinoma of the lung, and squamous carcinoma of the lung); melanoma; myeloma; neuroblastoma; oral cavity cancer (lip, tongue, mouth, and pharynx); ovarian cancer; pancreatic cancer; prostate cancer; retinoblastoma; rhabdomyosarcoma; rectal cancer; cancer of the respiratory system; salivary gland carcinoma; sarcoma; skin cancer; squamous cell cancer; stomach cancer; testicular cancer; thyroid cancer; uterine or endometrial cancer; cancer of the urinary system; vulval cancer; lymphoma including Hodgkin&#39;s and non-Hodgkin&#39;s lymphoma, as well as B-cell lymphoma (including low grade/follicular non-Hodgkin&#39;s lymphoma (NHL); small lymphocytic (SL) NHL; intermediate grade/follicular NHL; intermediate grade diffuse NHL; high grade immunoblastic NHL; high grade lymphoblastic NHL; high grade small non-cleaved cell NHL; bulky disease NHL; mantle cell lymphoma; AIDS-related lymphoma; and Waldenstrom&#39;s Macroglobulinemia; chronic lymphocytic leukemia (CLL); acute lymphoblastic leukemia (ALL); Hairy cell leukemia; chronic myeloblastic leukemia; as well as other carcinomas and sarcomas; and post-transplant lymphoproliferative disorder (PTLD), as well as abnormal vascular proliferation associated with phakomatoses, edema (e.g. that associated with brain tumors), and Meigs&#39; syndrome. 
     Tumor cells, or cancer cells also include, but are not limited to, carcinomas, e.g. various subtypes, including, for example, adenocarcinoma, basal cell carcinoma, squamous cell carcinoma, and transitional cell carcinoma), sarcomas (including, for example, bone and soft tissue), leukemias (including, for example, acute myeloid, acute lymphoblastic, chronic myeloid, chronic lymphocytic, and hairy cell), lymphomas and myelomas (including, for example, Hodgkin and non-Hodgkin lymphomas, light chain, non-secretory, MGUS, and plasmacytomas), and central nervous system cancers (including, for example, brain (e.g. gliomas (e.g. astrocytoma, oligodendroglioma, and ependymoma), meningioma, pituitary adenoma, and neuromas, and spinal cord tumors (e.g. meningiomas and neurofibroma). 
     Illustrative tumor antigens include, but are not limited to, MART-1/Melan-A, gp100, Dipeptidyl peptidase IV (DPPIV), adenosine deaminase-binding protein (ADAbp), cyclophilin b, Colorectal associated antigen (CRC)-0017-1A/GA733, Carcinoembryonic Antigen (CEA) and its immunogenic epitopes CAP-1 and CAP-2, etv6, aml1, Prostate Specific Antigen (PSA) and its immunogenic epitopes PSA-1, PSA-2, and PSA-3, prostate-specific membrane antigen (PSMA), T-cell receptor/CD3-zeta chain, MAGE-family of tumor antigens (e.g., MAGE-A1, MAGE-A2, MAGE-A3, MAGE-A4, MAGE-A5, MAGE-A6, MAGE-A7, MAGE-A8, MAGE-A9, MAGE-A10, MAGE-A11, MAGE-A12, MAGE-Xp2 (MAGE-B2), MAGE-Xp3 (MAGE-B3), MAGE-Xp4 (MAGE-B4), MAGE-C1, MAGE-C2, MAGE-C3, MAGE-C4, MAGE-C5), GAGE-family of tumor antigens (e.g., GAGE-1, GAGE-2, GAGE-3, GAGE-4, GAGE-5, GAGE-6, GAGE-7, GAGE-8, GAGE-9), BAGE, RAGE, LAGE-1, NAG, GnT-V, MUM-1, CDK4, tyrosinase, p53, MUC family, HER2/neu, p21ras, RCAS1, α-fetoprotein, E-cadherin, α-catenin, β-catenin and γ-catenin, p120ctn, gp100 Pme117, PRAME, NY-ESO-1, cdc27, adenomatous polyposis  coli  protein (APC), fodrin, Connexin 37, Ig-idiotype, p15, gp75, GM2 and GD2 gangliosides, viral products such as human papilloma virus proteins, Smad family of tumor antigens, Imp-1, NA, EBV-encoded nuclear antigen (EBNA)-1, brain glycogen phosphorylase, SSX-1, SSX-2 (HOM-MEL-40), SSX-1, SSX-4, SSX-5, SCP-1 CT-7, c-erbB-2, CD19, CD20, CD22, CD30, CD33, CD37, CD56, CD70, CD74, CD138, AGS16, MUC1, GPNMB, Ep-CAM, PD-L1, PD-L2, PMSA, and BCMA (TNFRSF17). In various embodiments, the CD8 binding agent comprises a targeting moiety that binds one or more of these tumor antigens. 
     In some embodiments, the present multi-specific CD8 binding agent recognizes and binds to CD8 as well as an antigen on a tumor cell. In some embodiments, the multi-specific CD8 binding agent directly or indirectly recruits CTLs to the tumor cell or tumor microenvironment. 
     In various embodiments, the present multi-specific CD8 binding agent has targeting moieties which target two different cells (e.g. to make a synapse) or the same cell (e.g. to get a more concentrated signaling agent effect). 
     In some embodiments, the multi-specific CD8 binding agent of the invention comprises a targeting moiety having an antigen recognition domain that specifically binds to a target (e.g. antigen, receptor) associated with T cells. In some embodiments, the targeting moiety recruits directly or indirectly T cells. In an embodiment, the antigen recognition domains specifically bind to effector T cells. In some embodiments, the antigen recognition domain directly or indirectly recruits effector T cells, e.g., in some embodiments, to a therapeutic site (e.g. a locus with one or more disease cell or cell to be modulated for a therapeutic effect). Illustrative effector T cells include cytotoxic T cells (e.g. αβ TCR, CD3 + , CD8 + , CD45RO + ); CD4 +  effector T cells (e.g. αβ TCR, CD3 + , CD4 + , CCR7 + , CD62Lhi, IL-7R/CD127 + ); CD8 +  effector T cells (e.g. αβ TCR, CD3 + , CD8 + , CCR7 + , CD62Lhi, IL-7R/CD127 + ); effector memory T cells (e.g. CD62Llow, CD44 + , TCR, CD3 + , IL-7R/CD127 + , IL-15R+, CCR7low); central memory T cells (e.g. CCR7 + , CD62L+, CD27 + ; or CCR7hi, CD44 + , CD62Lhi, TCR, CD3 + , IL-7R/CD127 + , IL-15R+); CD62L +  effector T cells; CD8 +  effector memory T cells (TEM) including early effector memory T cells (CD27 +  CD62L − ) and late effector memory T cells (CD27 −  CD62L − ) (TemE and TemL, respectively); CD127( + )CD25(low/−) effector T cells; CD127( − ) CD25( − ) effector T cells; CD8 +  stem cell memory effector cells (TSCM) (e.g. CD44(low)CD62L(high)CD122(high)sca( + )); TH1 effector T-cells (e.g. CXCR3 + , CXCR6 +  and CCR5 + ; or αβ TCR, CD3 + , CD4 + , IL-12R + , IFNγR + , CXCR3 + ), TH2 effector T cells (e.g. CCR3 + , CCR4 +  and CCR8 + ; or αβ TCR, CD3 + , CD4 + , IL-4R + , IL-33R + , CCR4 + , IL-17RB + , CRTH2 + ); TH9 effector T cells (e.g. αβ TCR, CD3 + , CD4 + ); TH17 effector T cells (e.g. αβ TCR, CD3 + , CD4 + , IL-23R+, CCR6 + , IL-1R + ); CD4 +  CD45RO + CCR7 +  effector T cells, ICOS +  effector T cells; CD4 + CD45RO + CCR7( − ) effector T cells; and effector T cells secreting IL-2, IL-4 and/or IFN-γ. 
     Illustrative T cell antigens of interest include, for example (and inclusive of the extracellular domains, where applicable): CD8, CD3, SLAMF4, IL-2Rα, 4-1BB/TNFRSF9, IL-2 R β, ALCAM, B7-1, IL-4 R, B7-H3, BLAME/SLAMFS, CEACAM1, IL-6 R, CCR3, IL-7 R α, CCR4, CXCRI/IL-S RA, CCR5, CCR6, IL-10R α, CCR7, IL-I 0 R β, CCRS, IL-12 R β 1, CCR9, IL-12 R β 2, CD2, IL-13 R α 1, IL-13, CD3, CD4, ILT2/CDS5j, ILT3/CDS5k, ILT4/CDS5d, ILT5/CDS5a, lutegrin α 4/CD49d, CDS, Integrin α E/CD103, CD6, Integrin α M/CD 11 b, CDS, Integrin α X/CD11c, Integrin β 2/CDIS, KIR/CD15S, CD27/TNFRSF7, KIR2DL1, CD2S, KIR2DL3, CD30/TNFRSFS, KIR2DL4/CD15Sd, CD31/PECAM-1, KIR2DS4, CD40 Ligand/TNFSF5, LAG-3, CD43, LAIR1, CD45, LAIR2, CDS3, Leukotriene B4-R1, CDS4/SLAMF5, NCAM-L1, CD94, NKG2A, CD97, NKG2C, CD229/SLAMF3, NKG2D, CD2F-10/SLAMF9, NT-4, CD69, NTB-A/SLAMF6, Common γ Chain/IL-2 R γ, Osteopontin, CRACC/SLAMF7, PD-1, CRTAM, PSGL-1, CTLA-4, RANK/TNFRSF11A, CX3CR1, CX3CL1, L-Selectin, CXCR3, SIRP β 1, CXCR4, SLAM, CXCR6, TCCR/WSX-1, DNAM-1, Thymopoietin, EMMPRIN/CD147, TIM-1, EphB6, TIM-2, Fas/TNFRSF6, TIM-3, Fas Ligand/TNFSF6, TIM-4, Fcγ RIII/CD16, TIM-6, TNFR1/TNFRSF1A, Granulysin, TNF RIII/TNFRSF1B, TRAIL RI/TNFRSFIOA, ICAM-1/CD54, TRAIL R2/TNFRSF10B, ICAM-2/CD102, TRAILR3/TNFRSF10C, IFN-γR1, TRAILR4/TNFRSF10D, IFN-γ R2, TSLP, IL-1 R1 and TSLP R. In various embodiments, the CD8 binding agent comprises a targeting moiety that binds one or more of these illustrative T cell antigens. 
     In some embodiments, the multi-specific CD8 binding agent of the invention comprises a targeting moiety having an antigen recognition domain that specifically binds to a target (e.g. antigen, receptor) associated with B cells. In some embodiments, the targeting moiety directly or indirectly recruits B cells, e.g., in some embodiments, to a therapeutic site (e.g. a locus with one or more disease cell or cell to be modulated for a therapeutic effect). 
     Illustrative B cell antigens of interest include, for example, CD10, CD19, CD20, CD21, CD22, CD23, CD24, CD37, CD38, CD39, CD40, CD70, CD72, CD73, CD74, CDw75, CDw76, CD77, CD78, CD79a/b, CD80, CD81, CD82, CD83, CD84, CD85, CD86, CD89, CD98, CD126, CD127, CDw130, CD138, CDw150, and B-cell maturation antigen (BCMA). In various embodiments, the CD8 binding agent comprises a targeting moiety that binds one or more of these illustrative B cell antigens. 
     In some embodiments, the multi-specific CD8 binding agent of the invention comprises a targeting moiety having an antigen recognition domain that specifically bind to a target (e.g. antigen, receptor) associated with Natural Killer cells. In some embodiments, the targeting moiety directly or indirectly recruits Natural Killer cells, e.g., in some embodiments, to a therapeutic site (e.g. a locus with one or more disease cell or cell to be modulated for a therapeutic effect). Illustrative Natural Killer cell antigens of interest include, for example TIGIT, 2B4/SLAMF4, KIR2DS4, CD155/PVR, KIR3DL1, CD94, LMIR1/CD300A, CD69, LMIR2/CD300c, CRACC/SLAMF7, LMIR3/CD300LF, Kir1alpha, DNAM-1, LMIR5/CD300LB, Fc-epsilon RII, LMIR6/CD300LE, Fc-γ RI/CD64, MICA, Fc-γ RIIB/CD32b, MICB, Fc-γ RIIC/CD32c, MULT-1, Fc-γ RIIA/CD32a, Nectin-2/CD112, Fc-γ RIII/CD16, NKG2A, FcRH1/IRTA5, NKG2C, FcRH2/IRTA4, NKG2D, FcRH4/IRTA1, NKp30, FcRH5/IRTA2, NKp44, Fc-Receptor-like 3/CD16-2, NKp46/NCR1, NKp80/KLRF1, NTB-A/SLAMF6, Rae-1, Rae-1 α, Rae-1 β, Rae-1 delta, H60, Rae-1 epsilon, ILT2/CD85j, Rae-1 γ, ILT3/CD85k, TREM-1, ILT4/CD85d, TREM-2, ILT5/CD85a, TREM-3, KIR/CD158, TREML1/TLT-1, KIR2DL1, ULBP-1, KIR2DL3, ULBP-2, KIR2DL4/CD158d and ULBP-3. In various embodiments, the CD8 binding agent comprises a targeting moiety that binds one or more of these illustrative NK cell antigens. 
     In some embodiments, the multi-specific CD8 binding agent of the invention comprises a targeting moiety having an antigen recognition domain that specifically binds to a target (e.g. antigen, receptor) associated with macrophages/monocytes. In some embodiments, the targeting moiety directly or indirectly recruits macrophages/monocytes, e.g., in some embodiments, to a therapeutic site (e.g. a locus with one or more disease cell or cell to be modulated for a therapeutic effect). Illustrative macrophages/monocyte antigens of interest include, for example SIRP1a, B7-1/CD80, ILT4/CD85d, B7-H1, ILT5/CD85a, Common β Chain, Integrin α 4/CD49d, BLAME/SLAMF8, Integrin α X/CDIIc, CCL6/C10, Integrin β 2/CD18, CD155/PVR, Integrin β 3/CD61, CD31/PECAM-1, Latexin, CD36/SR-B3, Leukotriene B4 R1, CD40/TNFRSF5, LIMPIIISR-B2, CD43, LMIR1/CD300A, CD45, LMIR2/CD300c, CD68, LMIR3/CD300LF, CD84/SLAMF5, LMIR5/CD300LB, CD97, LMIR6/CD300LE, CD163, LRP-1, CD2F-10/SLAMF9, MARCO, CRACC/SLAMF7, MD-1, ECF-L, MD-2, EMMPRIN/CD147, MGL2, Endoglin/CD105, Osteoactivin/GPNMB, Fc-γ RI/CD64, Osteopontin, Fc-γ RIIB/CD32b, PD-L2, Fc-γ RIIC/CD32c, Siglec-3/CD33, Fc-γ RIIA/CD32a, SIGNR1/CD209, Fc-γ RIII/CD16, SLAM, GM-CSF R α, TCCR/WSX-1, ICAM-2/CD102, TLR3, IFN-γ RI, TLR4, IFN-gannna R2, TREM-1, IL-I RII, TREM-2, ILT2/CD85j, TREM-3, ILT3/CD85k, TREML1/TLT-1, 2B4/SLAMF 4, IL-10 R α, ALCAM, IL-10 R β, AminopeptidaseN/ANPEP, ILT2/CD85j, Common β Chain, ILT3/CD85k, Clq R1/CD93, ILT4/CD85d, CCR1, ILT5/CD85a, CCR2, CD206, Integrin α 4/CD49d, CCR5, Integrin α M/CDII b, CCR8, Integrin α X/CDIIc, CD155/PVR, Integrin β 2/CD18, CD14, Integrin β 3/CD61, CD36/SR-B3, LAIR1, CD43, LAIR2, CD45, Leukotriene B4-R1, CD68, LIMPIIISR-B2, CD84/SLAMF5, LMIR1/CD300A, CD97, LMIR2/CD300c, CD163, LMIR3/CD300LF, Coagulation Factor III/Tissue Factor, LMIR5/CD300LB, CX3CR1, CX3CL1, LMIR6/CD300LE, CXCR4, LRP-1, CXCR6, M-CSF R, DEP-1/CD148, MD-1, DNAM-1, MD-2, EMMPRIN/CD147, MMR, Endoglin/CD105, NCAM-L1, Fc-γ RI/CD64, PSGL-1, Fc-γ RIIIICD16, RP105, G-CSF R, L-Selectin, GM-CSF R α, Siglec-3/CD33, HVEM/TNFRSF14, SLAM, ICAM-1/CD54, TCCR/WSX-1, ICAM-2/CD102, TREM-I, IL-6 R, TREM-2, CXCRI/IL-8 RA, TREM-3 and TREMLI/TLT-1. In various embodiments, the CD8 binding agent comprises a targeting moiety that binds one or more of these illustrative macrophage/monocyte antigens. 
     In some embodiments, the multi-specific CD8 binding agent of the invention comprises a targeting moiety having an antigen recognition domain that specifically binds to a target (e.g. antigen, receptor) associated with dendritic cells. In some embodiments, the targeting moiety directly or indirectly recruits dendritic cells, e.g., in some embodiments, to a therapeutic site (e.g. a locus with one or more disease cell or cell to be modulated for a therapeutic effect). Illustrative dendritic cell antigens of interest include, for example, CLEC9A, XCR1, RANK, CD36/SRB3, LOX-1/SR-E1, CD68, MARCO, CD163, SR-Ai/MSR, CD5L, SREC-1, CL-PI/COLEC12, SREC-II, LIMPIIISRB2, RP105, TLR4, TLR1, TLR5, TLR2, TLR6, TLR3, TLR9, 4-IBB Ligand/TNFSF9, IL-12/IL-23 p40, 4-Amino-1,8-naphthalimide, ILT2/CD85j, CCL21/6Ckine, ILT3/CD85k, 8-oxo-dG, ILT4/CD85d, 8D6A, ILT5/CD85a, A2B5, lutegrin α 4/CD49d, Aag, Integrin β 2/CD18, AMICA, Langerin, B7-2/CD86, Leukotriene B4 RI, B7-H3, LMIR1/CD300A, BLAME/SLAMF8, LMIR2/CD300c, Clq R1/CD93, LMIR3/CD300LF, CCR6, LMIR5/CD300LB CCR7, LMIR6/CD300LE, CD40/TNFRSF5, MAG/Siglec-4-a, CD43, MCAM, CD45, MD-1, CD68, MD-2, CD83, MDL-1/CLEC5A, CD84/SLAMF5, MMR, CD97, NCAMLI, CD2F-10/SLAMF9, Osteoactivin GPNMB, Chern 23, PD-L2, CLEC-1, RP105, CLEC-2, CLEC-8, Siglec-2/CD22, CRACC/SLAMF7, Siglec-3/CD33, DC-SIGN, DEC-205, Siglec-5, DC-SIGNR/CD299, Siglec-6, DCAR, Siglec-7, DCIR/CLEC4A, Siglec-9, DEC-205, Siglec-10, Dectin-1/CLEC7A, Siglec-F, Dectin-2/CLEC6A, SIGNR1/CD209, DEP-1/CD148, SIGNR4, DLEC, SLAM, EMMPRIN/CD147, TCCR/WSX-1, Fc-γ R1/CD64, TLR3, Fc-γ RIIB/CD32b, TREM-1, Fc-γ RIIC/CD32c, TREM-2, Fc-γ RIIA/CD32a, TREM-3, Fc-γ RII/CD16, TREML1/TLT-1, ICAM-2/CD102, DEC205, and Vanilloid R1. In various embodiments, the CD8 binding agent comprises a targeting moiety that binds one or more of these illustrative DC antigens. 
     In some embodiments, the multi-specific CD8 binding agent of the invention comprises a targeting moiety against Clec9A which is a VHH comprising a single amino acid chain having four “framework regions” or FRs and three “complementary determining regions” or CDRs. As used herein, “framework region” or “FR” refers to a region in the variable domain which is located between the CDRs. As used herein, “complementary determining region” or “CDR” refers to variable regions in VHHs that contains the amino acid sequences capable of specifically binding to antigenic targets. 
     In various embodiments, the multi-specific CD8 binding agent of the invention comprises a VHH against Clec9A having a variable domain comprising at least one CDR1, CDR2, and/or CDR3 sequences. 
     In exemplary embodiments, the CDR1 sequence is selected from SEQ ID NO: 303 to SEQ NO: 322. 
     In exemplary embodiments, the CDR2 sequence is selected from SEQ ID NO: 323 to SEQ ID NO: 344. 
     In exemplary embodiments, the CDR3 sequence is selected from SEQ ID NO: 345 to SEQ ID NO: 359; or LGR; or VIK. 
     In various embodiments, the Clec9A targeting moiety comprises an amino acid sequence selected from the following sequences: R2CHCL8 (SEQ ID NO:360); R1CHCL50 (SEQ ID NO:361); R1CHCL21 (SEQ ID NO:362); R2CHCL87 (SEQ ID NO:363); R2CHCL24 (SEQ ID NO:364); R2CHCL38 (SEQ ID NO:365); R1CHCL16 (SEQ ID NO:366); R2CHCL10 (SEQ ID NO:367); R1CHCL34 (SEQ ID NO:368); R1CHCL82 (SEQ ID NO:369); R2CHCL3 (SEQ ID NO:370); R2CHCL69 (SEQ ID NO:371); R1CHCL56 (SEQ ID NO:372); R2CHCL32 (SEQ ID NO:373); R2CHCL49 (SEQ ID NO:374); R2CHCL53 (SEQ ID NO:375); R2CHCL22 (SEQ ID NO:376); R2CHCL25 (SEQ ID NO:377); R2CHCL18 (SEQ ID NO:378); R1CHCL23 (SEQ ID NO:379); R1CHCL27 (SEQ ID NO:380); R2CHCL13 (SEQ ID NO:381); R2CHCL14 (SEQ ID NO:382); R2CHCL42 (SEQ ID NO:383); R2CHCL41 (SEQ ID NO:384); R2CHCL94 (SEQ ID NO:385); or R2CHCL27 (SEQ ID NO:386). 
     In various embodiments, the Clec9A targeting moiety comprises a VHH having a variable domain comprising at least one CDR1, CDR2, and/or CDR3 sequences as described below. 
     In some embodiments, the CDR1 sequence is selected from SEQ ID NO: 387 to SEQ ID NO: 452. 
     In some embodiments, the CDR2 sequence is selected from SEQ ID NO: 453 to SEQ ID NO: 518. 
     In some embodiments, the CDR3 sequence is selected from SEQ ID NO: 519 to SEQ ID NO: 584. 
     In various exemplary embodiments, the Clec9A targeting moiety comprises an amino acid sequence selected from the following sequences: 1LEC 7 (SEQ ID NO:585) or 1LEC 9 (SEQ ID NO:586) or 1LEC 26 (SEQ ID NO:587) or 1LEC 27 (SEQ ID NO:588) or 1LEC 28 (SEQ ID NO:589) or 1LEC 30 (SEQ ID NO:590) or 1LEC 38 (SEQ ID NO:591) or 1LEC 42 (SEQ ID NO:592) or 1LEC 51 (SEQ ID NO:593) or 1LEC 61 (SEQ ID NO:594) or 1LEC 62 (SEQ ID NO:595) or 1LEC 63 (SEQ ID NO:596) or 1LEC 64 (SEQ ID NO:597) or 1LEC 70 (SEQ ID NO:598) or 1LEC 84 (SEQ ID NO:599) or 1LEC 88 (SEQ ID NO:600) or 1LEC 91 (SEQ ID NO:601) or 1LEC 92 (SEQ ID NO:602) or 1LEC 94 (SEQ ID NO:603) or 2LEC 6 (SEQ ID NO:604) or 2LEC 13 (SEQ ID NO:605) or 2LEC 16 (SEQ ID NO:606) or 2LEC 20 (SEQ ID NO:607) or 2LEC 23 (SEQ ID NO:608) or 2LEC 24 (SEQ ID NO:609) or 2LEC 26 (SEQ ID NO:610) or 2LEC 38 (SEQ ID NO:611) or 2LEC 48 (SEQ ID NO:612) or 2LEC 53 (SEQ ID NO:613) or 2LEC 54 (SEQ ID NO:614) or 2LEC 55 (SEQ ID NO:615) or 2LEC 59 (SEQ ID NO:616) or 2LEC 60 (SEQ ID NO:617) or 2LEC 61 (SEQ ID NO:618) or 2LEC 62 (SEQ ID NO:619) or 2LEC 63 (SEQ ID NO:620) or 2LEC 67 (SEQ ID NO:621) or 2LEC 68 (SEQ ID NO:622) or 2LEC 76 (SEQ ID NO:623) or 2LEC 83 (SEQ ID NO:624) or 2LEC 88 (SEQ ID NO:625) or 2LEC 89 (SEQ ID NO:626) or 2LEC 90 (SEQ ID NO:627) or 2LEC 93 (SEQ ID NO:628) or 2LEC 95 (SEQ ID NO:629) or 3LEC 4 (SEQ ID NO:630) or 3LEC 6 (SEQ ID NO:631) or 3LEC 9 (SEQ ID NO:632) or 3LEC 11 (SEQ ID NO:633) or 3LEC 13 (SEQ ID NO:634) or 3LEC 15 (SEQ ID NO:635) or 3LEC 22 (SEQ ID NO:636) or 3LEC 23 (SEQ ID NO:637) or 3LEC 27 (SEQ ID NO:638) or 3LEC 30 (SEQ ID NO:639) or 3LEC 36 (SEQ ID NO:640) or 3LEC 55 (SEQ ID NO:641) or 3LEC 57 (SEQ ID NO:642) or 3LEC 61 (SEQ ID NO:643) or 3LEC 62 (SEQ ID NO:644) or 3LEC 66 (SEQ ID NO:645) or 3LEC 69 (SEQ ID NO:646) or 3LEC 76 (SEQ ID NO:647) or 3LEC 82 (SEQ ID NO:648) or 3LEC 89 (SEQ ID NO:649) or 3LEC 94 (SEQ ID NO:650). In various exemplary embodiments, the Clec9A targeting moiety comprises an amino acid sequence selected from any one of the above sequences without the terminal histidine tag sequence (i.e., HHHHHH, SEQ ID NO: 1213). 
     In some embodiments, the Clec9A targeting moiety comprises an amino acid sequence selected from any one of the above sequences without the HA tag (i.e., YPYDVPDYGS; SEQ ID NO: 1214). 
     In some embodiments, the Clec9A targeting moiety comprises an amino acid sequence selected from any one of the above sequences without the AAA linker. 
     In some embodiments, the Clec9A targeting moiety comprises an amino acid sequence selected from any one of the above sequences without the AAA linker, HA tag, and terminal histidine tag sequence (i.e., 
     
       
         
           
               
               
            
               
                   
                 AAAYPYDVPDYGSHHHHHH; SEQ ID NO: 1215) 
               
            
           
         
       
     
     In an embodiment, the targeting moiety comprises the anti-Clec9A antibody as disclosed in Tullett et al., JCI Insight. 2016; 1(7):e87102, the entire disclosures of which are hereby incorporated by reference. 
     In various embodiments, the present invention contemplates the use of any natural or synthetic analogs, mutants, variants, alleles, homologs and orthologs (herein collectively referred to as “analogs”) of the targeting moiety directed against Clec9A as described herein. In various embodiments, the amino acid sequence of the targeting moiety directed against Clec9A further includes an amino acid analog, an amino acid derivative, or other non-classical amino acids. 
     In various embodiments, the present chimeric protein comprises a targeting moiety comprising an amino acid sequence that is at least 60% identical to any one of the sequences disclosed herein. For example, the chimeric protein may comprise a targeting moiety comprising an amino acid sequence that is at least about 60%, at least about 61%, at least about 62%, at least about 63%, at least about 64%, at least about 65%, at least about 66%, at least about 67%, at least about 68%, at least about 69%, at least about 70%, at least about 71%, at least about 72%, at least about 73%, at least about 74%, at least about 75%, at least about 76%, at least about 77%, at least about 78%, at least about 79%, at least about 80%, at least about 81%, at least about 82%, at least about 83%, at least about 84%, at least about 85%, at least about 86%, at least about 87%, at least about 88%, at least about 89%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or 100% identical to any one of the sequences discloses herein (e.g. about 60%, or about 61%, or about 62%, or about 63%, or about 64%, or about 65%, or about 66%, or about 67%, or about 68%, or about 69%, or about 70%, or about 71%, or about 72%, or about 73%, or about 74%, or about 75%, or about 76%, or about 77%, or about 78%, or about 79%, or about 80%, or about 81%, or about 82%, or about 83%, or about 84%, or about 85%, or about 86%, or about 87%, or about 88%, or about 89%, or about 90%, or about 91%, or about 92%, or about 93%, or about 94%, or about 95%, or about 96%, or about 97%, or about 98%, about 99% or about 100% sequence identity to any one of the sequences disclosed herein). 
     In some embodiments, the multi-specific CD8 binding agent of the invention comprises a targeting moiety having an antigen recognition domain that specifically binds a target (e.g. antigen, receptor) on immune cells selected from, but not limited to, megakaryocytes, thrombocytes, erythrocytes, mast cells, basophils, neutrophils, and eosinophils. In some embodiments, the antigen recognition domains directly or indirectly recruit megakaryocytes, thrombocytes, erythrocytes, mast cells, basophils, neutrophils, and eosinophil, e.g., in some embodiments, to a therapeutic site (e.g. a locus with one or more disease cell or cell to be modulated for a therapeutic effect). 
     In some embodiments, the multi-specific CD8 binding agent of the invention comprises a targeting moiety having an antigen recognition domain that specifically binds to a target (e.g. antigen, receptor) associated with megakaryocytes and/or thrombocytes. Illustrative megakaryocyte and/or thrombocyte antigens of interest include, for example, GP IIb/IIIa, GPIb, vWF, PF4, and TSP. In various embodiments, the CD8 binding agent comprises a targeting moiety that binds one or more of these illustrative megakaryocyte and/or thrombocyte antigens. 
     In some embodiments, the multi-specific CD8 binding agent of the invention comprises a targeting moiety having an antigen recognition domain that specifically binds to a target (e.g. antigen, receptor) associated with erythrocytes. Illustrative erythrocyte antigens of interest include, for example, CD34, CD36, CD38, CD41a (platelet glycoprotein IIb/IIIa), CD41b (GPIIb), CD71 (transferrin receptor), CD105, glycophorin A, glycophorin C, c-kit, HLA-DR, H2 (MHC-II), and Rhesus antigens. In various embodiments, the CD8 binding agent comprises a targeting moiety that binds one or more of these illustrative erythrocyte antigens. 
     In some embodiments, the multi-specific CD8 binding agent of the invention comprises a targeting moiety having an antigen recognition domain that specifically binds to a target (e.g. antigen, receptor) associated with mast cells. Illustrative mast cells antigens of interest include, for example, SCFR/CD117, Fc ε RI, CD2, CD25, CD35, CD88, CD203c, C5R1, CMAI, FCERIA, FCER2, TPSABI. In various embodiments, the CD8 binding agent comprises a targeting moiety that binds one or more of these mast cell antigens. 
     In some embodiments, the multi-specific CD8 binding agent of the invention comprises a targeting moiety having an antigen recognition domain that specifically binds to a target (e.g. antigen, receptor) associated with basophils. Illustrative basophils antigens of interest include, for example, Fc ε RI, CD203c, CD123, CD13, CD107a, CD107b, and CD164. In various embodiments, the CD8 binding agent comprises a targeting moiety that binds one or more of these basophil antigens. 
     In some embodiments, the multi-specific CD8 binding agent of the invention comprises a targeting moiety having an antigen recognition domain that specifically binds to a target (e.g. antigen, receptor) associated with neutrophils. Illustrative neutrophils antigens of interest include, for example, 7D5, CD10/CALLA, CD13, CD16 (FcRIII), CD18 proteins (LFA-1, CR3, and p150, 95), CD45, CD67, and CD177. In various embodiments, the CD8 binding agent comprises a targeting moiety that binds one or more of these neutrophil antigens. 
     In some embodiments, the multi-specific CD8 binding agent of the invention comprises a targeting moiety having an antigen recognition domain that specifically binds to a target (e.g. antigen, receptor) associated with eosinophils. Illustrative eosinophils antigens of interest include, for example, CD35, CD44 and CD69. In various embodiments, the CD8 binding agent comprises a targeting moiety that binds one or more of these eosinophil antigens. 
     In various embodiments, the multi-specific CD8 binding agent of the invention comprises a targeting moiety having an antigen recognition domain that specifically binds to any appropriate antigen or receptor or cell surface markers known by the skilled artisan. In some embodiments, the antigen or cell surface marker is a tissue-specific marker. Illustrative tissue-specific markers include, but are not limited to, endothelial cell surface markers such as ACE, CD14, CD34, CDH5, ENG, ICAM2, MCAM, NOS3, PECAMI, PROCR, SELE, SELP, TEK, THBD, VCAMI, VWF; smooth muscle cell surface markers such as ACTA2, MYHIO, MYHI 1, MYH9, MYOCD; fibroblast (stromal) cell surface markers such as ALCAM, CD34, COLIAI, COL1A2, COL3A1, FAP, PH-4; epithelial cell surface markers such as CDID, K6IRS2, KRTIO, KRT13, KRT17, KRT18, KRT19, KRT4, KRT5, KRT8, MUCI, TACSTDI; neovasculature markers such as CD13, TFNA, Alpha-v beta-3 (α v β 3 ), E-selectin; and adipocyte surface markers such as ADIPOQ, FABP4, and RETN. In various embodiments, the CD8 binding agent comprises a targeting moiety that binds one or more of these antigens. 
     In various embodiments, the multi-specific CD8 binding agent of the invention comprises a targeting moiety having an antigen recognition domain that specifically binds to a checkpoint marker expressed on a T cell, e.g. one or more of PD-1, CD28, CTLA4, ICOS, BTLA, KIR, LAG3, CD137, OX40, CD27, CD40L, TIM3, and A2aR. 
     In various embodiments, the multi-specific CD8 binding agent of the invention comprises a targeting moiety having an antigen recognition domain that specifically binds to a checkpoint marker, e.g. one or more of PD-1/PD-L1 or PD-L2, CD28/CD80 or CD86, CTLA4/CD80 or CD86, ICOS/ICOSL or B7RP1, BTLA/HVEM, KIR, LAG3, CD137/CD137L, OX40/OX40L, CD27, CD40L, TIM3/Gal9, and A2aR. 
     By way of non-limiting example, in various embodiments, the present multispecific CD8 binding agent comprises a targeting moiety directed against (i) CD8; (ii) a checkpoint marker expressed on a T cell, e.g. one or more of PD-1, CD28, CTLA4, ICOS, BTLA, KIR, LAG3, CD137, OX40, Cd27, CD40L, TIM3, and A2aR and/or (iii) a targeting moiety is directed against a tumor cell, along with any of the modified (e.g. mutant) signaling agents described herein. 
     In various embodiments, the present multi-specific CD8 binding agent has one or more targeting moieties directed against PD-1. In some embodiments, the CD8 binding agent has one or more targeting moieties which selectively bind a PD-1 polypeptide. In some embodiments, the CD8 binding agent comprises one or more antibodies, antibody derivatives or formats, peptides or polypeptides, or fusion proteins that selectively bind a PD-1 polypeptide. 
     In various embodiments, the multi-specific CD8 binding agent of the invention comprises a VHH against PD1 having a variable domain comprising at least one CDR1, CDR2, and/or CDR3 sequences. 
     In some embodiments, the CDR1 sequence is selected from SEQ ID NO: 651 to SEQ ID NO: 664. 
     In some embodiments, the CDR2 sequence is selected from SEQ ID NOL 665 to SEQ ID NO: 678. 
     In some embodiments, the CDR3 sequence is selected from SEQ ID NO: 679 to SEQ ID NO: 692. 
     In various exemplary embodiments, the PD1 targeting moiety comprises an amino acid sequence selected from the following sequences: 2PD23 (SEQ ID NO: 693); or 2PD26 (SEQ ID NO: 694); or 2PD90 (SEQ ID NO: 695); or 2PD106 (SEQ ID NO: 696); or 2PD16 (SEQ ID NO: 697); or 2PD71 (SEQ ID NO: 698); or 2PD152 (SEQ ID NO: 699); or 2PD12 (SEQ ID NO: 700); or 3PD55 (SEQ ID NO: 701); or 3PD82 (SEQ ID NO: 702); or 2PD8 (SEQ ID NO: 703); or 2PD27 (SEQ ID NO: 704); or 2PD82 (SEQ ID NO: 705); or 3PD36 (SEQ ID NO: 706). 
     In various exemplary embodiments, the PD1 targeting moiety comprises an amino acid sequence selected from any one of the above without the terminal histidine tag sequence (i.e., HHHHHH, SEQ ID NO: 1213). 
     In some embodiments, the PD1 targeting moiety comprises an amino acid sequence selected from any one of the above sequences without the HA tag (i.e., YPYDVPDYGS; SEQ ID NO: 1214). 
     In some embodiments, the PD1 targeting moiety comprises an amino acid sequence selected from any one of the above sequences without the AAA linker. 
     In some embodiments, the PD1 targeting moiety comprises an amino acid sequence selected from any one of the above sequences without the AAA linker, HA tag, and terminal histidine tag sequence (i.e., 
     
       
         
           
               
               
            
               
                   
                 AAAYPYDVPDYGSHHHHHH; SEQ ID NO: 1215) 
               
            
           
         
       
     
     In an embodiment, the targeting moiety comprises the anti-PD-1 antibody pembrolizumab (aka MK-3475, KEYTRUDA), or fragments thereof. Pembrolizumab and other humanized anti-PD-1 antibodies are disclosed in Hamid, et al. (2013) New England Journal of Medicine 369 (2): 134-44, U.S. Pat. No. 8,354,509, and WO 2009/114335, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, pembrolizumab or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain comprising the amino acid sequence of SEQ ID NO:707; and/or a light chain comprising the amino acid sequence of SEQ ID NO:708. 
     In an embodiment, the targeting moiety comprises the anti-PD-1 antibody, nivolumab (aka BMS-936558, MDX-1106, ONO-4538, OPDIVO), or fragments thereof. Nivolumab (clone 5C4) and other human monoclonal antibodies that specifically bind to PD-1 are disclosed in U.S. Pat. No. 8,008,449 and WO 2006/121168, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, nivolumab or an antigen-binding fragment thereof comprises a heavy chain comprising the amino acid sequence of SEQ ID NO:709; and/or a light chain comprising the amino acid sequence of SEQ ID NO:710. 
     In an embodiment, the targeting moiety comprises the anti-PD-1 antibody pidilizumab (aka CT-011, hBAT or hBAT-1), or fragments thereof. Pidilizumab and other humanized anti-PD-I monoclonal antibodies are disclosed in US 2008/0025980 and WO 2009/101611, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, the anti-PD-1 antibody or an antigen-binding fragment thereof for use in the methods provided herein comprises a light chain variable regions comprising an amino acid sequence selected from SEQ ID NOS: 15-18 of US 2008/0025980: SEQ ID NO: 15 of US 2008/0025980 (SEQ ID NO:711); SEQ ID NO: 16 of US 2008/0025980 (SEQ ID NO:712); SEQ ID NO: 17 of US 2008/0025980 (SEQ ID NO:713); SEQ ID NO: 18 of US 2008/0025980 (SEQ ID NO:714); and/or a heavy chain comprising an amino acid sequence selected from SEQ ID NOS: 20-24 of US 2008/0025980: SEQ ID NO: 20 of US 2008/0025980 (SEQ ID NO:715); SEQ ID NO: 21 of US 2008/0025980 (SEQ ID NO:716); SEQ ID NO: 22 of US 2008/0025980 (SEQ ID NO:717); SEQ ID NO: 23 of US 2008/0025980 (SEQ ID NO:718); or SEQ ID NO: 24 of US 2008/0025980 (SEQ ID NO:719). 
     In an embodiment, the targeting moiety comprises a light chain comprising SEQ ID NO:18 of US 2008/0025980 and a heavy chain comprising SEQ ID NO:22 of US 2008/0025980. 
     In an embodiment, the targeting moiety comprises AMP-514 (aka MEDI-0680). 
     In an embodiment, the targeting moiety comprises the PD-L2-Fc fusion protein AMP-224, which is disclosed in WO2010/027827 and WO 2011/066342, the entire disclosures of which are hereby incorporated by reference. In such an embodiment, the targeting moiety may include a targeting domain which comprises SEQ ID NO:4 of WO2010/027827 (SEQ ID NO:720) and/or the B7-DC fusion protein which comprises SEQ ID NO:83 of WO2010/027827 (SEQ ID NO:721). 
     In an embodiment, the targeting moiety comprises the peptide AUNP 12 or any of the other peptides disclosed in US 2011/0318373 or 8,907,053. For example, the targeting moiety may comprise AUNP 12 (i.e., Compound 8 or SEQ ID NO:49 of US 2011/0318373) which has the sequence of SEQ ID NO:722: 
     
       
         
         
             
             
         
       
     
     In an embodiment, the targeting moiety comprises the anti-PD-1 antibody 1E3, or fragments thereof, as disclosed in US 2014/0044738, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, 1E3 or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:723; and/or alight chain variable region comprising the amino acid sequence of SEQ ID NO:724. 
     In an embodiment, the targeting moiety comprises the anti-PD-1 antibody 1E8, or fragments thereof, as disclosed in US 2014/0044738, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, 1E8 or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:725; and/or alight chain variable region comprising the amino acid sequence of SEQ ID NO:726. 
     In an embodiment, the targeting moiety comprises the anti-PD-1 antibody 1H3, or fragments thereof, as disclosed in US 2014/0044738, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, 1H3 or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:727; and/or light chain variable region comprising the amino acid sequence of SEQ ID NO:728. 
     In an embodiment, the targeting moiety comprises a VHH directed against PD-1 as disclosed, for example, in U.S. Pat. No. 8,907,065 and WO 2008/071447, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, the VHHs against PD-1 comprise SEQ ID NOS: 347-351 of U.S. Pat. No. 8,907,065: SEQ ID NO: 347 of U.S. Pat. No. 8,907,065 (SEQ ID NO:729); SEQ ID NO: 348 of U.S. Pat. No. 8,907,065 (SEQ ID NO:730); SEQ ID NO: 349 of U.S. Pat. No. 8,907,065 (SEQ ID NO:731); SEQ ID NO: 350 of U.S. Pat. No. 8,907,065 (SEQ ID NO:732); or SEQ ID NO: 351 of U.S. Pat. No. 8,907,065 (SEQ ID NO:733). 
     In an embodiment, the targeting moiety comprises any one of the anti-PD-1 antibodies, or fragments thereof, as disclosed in US2011/0271358 and WO2010/036959, the entire contents of which are hereby incorporated by reference. In illustrative embodiments, the antibody or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain comprising an amino acid sequence selected from SEQ ID NOS: 25-29 of US2011/0271358: SEQ ID NO: 25 of US2011/0271358 (SEQ ID NO:734); SEQ ID NO: 26 of US2011/0271358 (SEQ ID NO:735); SEQ ID NO: 27 of US2011/0271358 (SEQ ID NO:736); SEQ ID NO: 28 of US2011/0271358 (SEQ ID NO:737); SEQ ID NO: 29 of US2011/0271358 (SEQ ID NO:738); and/or alight chain comprising an amino acid sequence selected from SEQ ID NOS: 30-33 of US2011/0271358: SEQ ID NO: 30 of US2011/0271358 (SEQ ID NO:739); SEQ ID NO: 31 of US2011/0271358 (SEQ ID NO:740); SEQ ID NO: 32 of US2011/0271358 (SEQ ID NO:741); or SEQ ID NO: 33 of US2011/0271358 (SEQ ID NO:742). 
     In various embodiments, the present multi-specific CD8 binding agent comprises one or more antibodies directed against PD-1, or antibody fragments thereof, selected from TSR-042 (Tesaro, Inc.), REGN2810 (Regeneron Pharmaceuticals, Inc.), PDR001 (Novartis Pharmaceuticals), and BGB-A317 (BeiGene Ltd.) In various embodiments, the present multi-specific CD8 binding agent has one or more targeting moieties directed against PD-L1. In some embodiments, the CD8 binding agent has one or more targeting moieties which selectively bind a PD-L1 polypeptide. In some embodiments, the CD8 binding agent comprises one or more antibodies, antibody derivatives or formats, peptides or polypeptides, or fusion proteins that selectively bind a PD-L1 polypeptide. 
     In various embodiments, the multi-specific CD8 binding agent of the invention comprises a VHH against PD-L1 having a variable domain comprising at least one CDR1, CDR2, and/or CDR3 sequences. 
     In some embodiments, the CDR1 sequence is selected from SEQ ID NO: 743 to SEQ ID NO: 773. 
     In some embodiments, the CDR2 sequence is selected from SEQ ID NO: 774 to SEQ ID NO: 804. 
     In some embodiments, the CDR3 sequence is selected from SEQ ID NO: 805 to SEQ ID NO: 835. 
     In various exemplary embodiments, the PD-L1 targeting moiety comprises an amino acid sequence selected from the following sequences: 2LIG2 (SEQ ID NO: 836); or 2LIG3 (SEQ ID NO: 837); or 2LIG16 (SEQ ID NO: 838) or 2LIG22 (SEQ ID NO: 839) or 2LIG27 (SEQ ID NO: 840) or 2LIG29 (SEQ ID NO: 841) or 2LIG30 (SEQ ID NO: 842) or 2LIG34 (SEQ ID NO: 843) or 2LIG35 (SEQ ID NO: 844) or 2LIG48 (SEQ ID NO: 845) or 2LIG65 (SEQ ID NO: 846) or 2LIG85 (SEQ ID NO: 847) or 2LIG86 (SEQ ID NO: 848) or 2LIG89 (SEQ ID NO: 849) or 2LIG97 (SEQ ID NO: 850) or 2LIG99 (SEQ ID NO: 851) or 2LIG109 (SEQ ID NO: 852) or 2LIG127 (SEQ ID NO: 853) or 2LIG139 (SEQ ID NO: 854) or 2LIG176 (SEQ ID NO: 855) or 2LIG189 (SEQ ID NO: 856) or 3LIG3 (SEQ ID NO: 857) or 3LIG7 (SEQ ID NO: 858) or 3LIG8 (SEQ ID NO: 859) or 3LIG9 (SEQ ID NO: 860) or 3LIG18 (SEQ ID NO: 861) or 3LIG20 (SEQ ID NO: 862) or 3LIG28 (SEQ ID NO: 863) or 3LIG29 (SEQ ID NO: 864) or 3LIG30 (SEQ ID NO: 865) or 3LIG33 (SEQ ID NO: 866). 
     In various exemplary embodiments, the PD-L1 targeting moiety comprises an amino acid sequence selected from any one of the above sequences without the terminal histidine tag sequence (i.e., HHHHHH, SEQ ID NO: 1213). 
     In some embodiments, the PD-L1 targeting moiety comprises an amino acid sequence selected from any one of the above sequences without the HA tag (i.e., YPYDVPDYGS; SEQ ID NO: 1214). 
     In some embodiments, the PD-L1 targeting moiety comprises an amino acid sequence selected from any one of the above sequences without the AAA linker. 
     In some embodiments, the PD-L1 targeting moiety comprises an amino acid sequence selected from any one of the above sequences without the AAA linker, HA tag, and terminal histidine tag sequence (i.e., 
     
       
         
           
               
               
               
            
               
                   
                   
                 AAAYPYDVPDYGSHHHHHH; SEQ ID NO: 1215) 
               
            
           
         
       
     
     In an embodiment, the targeting moiety comprises the anti-PD-L1 antibody MEDI4736 (aka durvalumab), or fragments thereof. MEDI4736 is selective for PD-L1 and blocks the binding of PD-L1 to the PD-1 and CD80 receptors. MEDI4736 and antigen-binding fragments thereof for use in the methods provided herein comprises a heavy chain and a light chain or a heavy chain variable region and a light chain variable region. The sequence of MEDI4736 is disclosed in WO/2016/06272, the entire contents of which are hereby incorporated by reference. In illustrative embodiments, MEDI4736 or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain comprising the amino acid sequence of (SEQ ID NO:867); and/or a light chain comprising the amino acid sequence of (SEQ ID NO:868). 
     In illustrative embodiments, the MED14736 or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:4 of WO/2016/06272 (SEQ ID NO:869); and/or a light chain variable region comprising the amino acid sequence of SEQ ID NO:3 of WO/2016/06272 (SEQ ID NO:870). 
     In an embodiment, the targeting moiety comprises the anti-PD-L1 antibody atezolizumab (aka MPDL3280A, RG7446), or fragments thereof. In illustrative embodiments, atezolizumab or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain comprising the amino acid sequence of: SEQ ID NO:871); and/or a light chain comprising the amino acid sequence of SEQ ID NO:872. 
     In an embodiment, the targeting moiety comprises the anti-PD-L1 antibody avelumab (aka MSB0010718C), or fragments thereof. In illustrative embodiments, avelumab or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain comprising the amino acid sequence of SEQ ID NO:873; and/or a light chain comprising the amino acid sequence of SEQ ID NO:874. 
     In an embodiment, the targeting moiety comprises the anti-PD-L1 antibody BMS-936559 (aka 12A4, MDX-1105), or fragments thereof, as disclosed in US 2013/0309250 and WO2007/005874, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, BMS-936559 or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:875; and/or a light chain variable region comprising the amino acid sequence of SEQ ID NO:876. 
     In an embodiment, the targeting moiety comprises the anti-PD-L1 antibody 3G10, or fragments thereof, as disclosed in US 2013/0309250 and WO2007/005874, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, 3G10 or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:877; and/or a light chain variable region comprising the amino acid sequence of SEQ ID NO:878. 
     In an embodiment, the targeting moiety comprises the anti-PD-L1 antibody 10A5, or fragments thereof, as disclosed in US 2013/0309250 and WO2007/005874, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, 10A5 or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:879; and/or a light chain variable region comprising the amino acid sequence of SEQ ID NO:880. 
     In an embodiment, the targeting moiety comprises the anti-PD-L1 antibody 5F8, or fragments thereof, as disclosed in US 2013/0309250 and WO2007/005874, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, 5F8 or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:881; and/or a light chain variable region comprising the amino acid sequence of SEQ ID NO:882. 
     In an embodiment, the targeting moiety comprises the anti-PD-L1 antibody 10H10, or fragments thereof, as disclosed in US 2013/0309250 and WO2007/005874, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, 10H10 or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:883); and/or a light chain variable region comprising the amino acid sequence of SEQ ID NO:884. 
     In an embodiment, the targeting moiety comprises the anti-PD-L1 antibody 1B12, or fragments thereof, as disclosed in US 2013/0309250 and WO2007/005874, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, 1B12 or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:885; and/or a light chain variable region comprising the amino acid sequence of SEQ ID NO:886. 
     In an embodiment, the targeting moiety comprises the anti-PD-L1 antibody 7H1, or fragments thereof, as disclosed in US 2013/0309250 and WO2007/005874, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, 7H1 or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:887; and/or a light chain variable region comprising the amino acid sequence of SEQ ID NO:888. 
     In an embodiment, the targeting moiety comprises the anti-PD-L1 antibody 11E6, or fragments thereof, as disclosed in US 2013/0309250 and WO2007/005874, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, 11E6 or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:889; and/or a light chain variable region comprising the amino acid sequence of SEQ ID NO:890. 
     In an embodiment, the targeting moiety comprises the anti-PD-L1 antibody 12B7, or fragments thereof, as disclosed in US 2013/0309250 and WO2007/005874, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, 12B7 or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:891; and/or a light chain variable region comprising the amino acid sequence of SEQ ID NO:892. 
     In an embodiment, the targeting moiety comprises the anti-PD-L1 antibody 13G4, or fragments thereof, as disclosed in US 2013/0309250 and WO2007/005874, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, 13G4 or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:893; and/or a light chain variable region comprising the amino acid sequence of SEQ ID NO:894. 
     In an embodiment, the targeting moiety comprises the anti-PD-L1 antibody 1E12, or fragments thereof, as disclosed in US 2014/0044738, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, 1E12 or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:895; and/or alight chain variable region comprising the amino acid sequence of SEQ ID NO:896. 
     In an embodiment, the targeting moiety comprises the anti-PD-L1 antibody 1F4, or fragments thereof, as disclosed in US 2014/0044738, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, 1F4 or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:897; and/or alight chain variable region comprising the amino acid sequence of SEQ ID NO:898. 
     In an embodiment, the targeting moiety comprises the anti-PD-L1 antibody 2G11, or fragments thereof, as disclosed in US 2014/0044738, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, 2G11 or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:899; and/or alight chain variable region comprising the amino acid sequence of SEQ ID NO:900. 
     In an embodiment, the targeting moiety comprises the anti-PD-L1 antibody 3B6, or fragments thereof, as disclosed in US 2014/0044738, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, 3B6 or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:901; and/or alight chain variable region comprising the amino acid sequence of SEQ ID NO:902. 
     In an embodiment, the targeting moiety comprises the anti-PD-L1 antibody 3D10, or fragments thereof, as disclosed in US 2014/0044738 and WO2012/145493, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, 3D10 or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:903; and/or a light chain variable region comprising the amino acid sequence of SEQ ID NO:904. 
     In an embodiment, the targeting moiety comprises any one of the anti-PD-L1 antibodies disclosed in US2011/0271358 and WO2010/036959, the entire contents of which are hereby incorporated by reference. In illustrative embodiments, the antibody or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain comprising an amino acid sequence selected from SEQ ID NOs: 34-38 of US2011/0271358: SEQ ID NO: 34 of US2011/0271358 (SEQ ID NO:905); SEQ ID NO: 35 of US2011/0271358 (SEQ ID NO:906); SEQ ID NO: 36 of US2011/0271358 (SEQ ID NO:907); SEQ ID NO: 37 of US2011/0271358 (SEQ ID NO:908); SEQ ID NO: 38 of US2011/0271358 (SEQ ID NO:909); and/or alight chain comprising an amino acid sequence selected from SEQ ID NOs: 39-42 of US2011/0271358: SEQ ID NO: 39 of US2011/0271358 (SEQ ID NO:910); SEQ ID NO: 40 of US2011/0271358 (SEQ ID NO:911); SEQ ID NO: 41 of US2011/0271358 (SEQ ID NO:912); or SEQ ID NO: 42 of US2011/0271358 (SEQ ID NO:913). 
     In an embodiment, the targeting moiety comprises the anti-PD-L1 antibody 2.7A4, or fragments thereof, as disclosed in WO 2011/066389, U.S. Pat. No. 8,779,108, and US2014/0356353, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, 2.7A4 or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain variable region comprising the amino acid sequence of: SEQ ID NO: 2 of WO 2011/066389 (SEQ ID NO:914); and/or a light chain variable region comprising the amino acid sequence of SEQ ID NO: 7 of WO 2011/066389 (SEQ ID NO:915). 
     In an embodiment, the targeting moiety comprises the anti-PD-L1 antibody 2.9D10, or fragments thereof, as disclosed in WO 2011/066389, U.S. Pat. No. 8,779,108, and US2014/0356353, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, 2.9D10 or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 12 of WO 2011/066389 (SEQ ID NO:916); and/or a light chain variable region comprising the amino acid sequence of SEQ ID NO: 17 of WO 2011/066389 (SEQ ID NO:917). 
     In an embodiment, the targeting moiety comprises the anti-PD-L1 antibody 2.14H9, or fragments thereof, as disclosed in WO 2011/066389, U.S. Pat. No. 8,779,108, and US2014/0356353, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, 2.14H9 or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 22 of WO 2011/066389 (SEQ ID NO:918); and/or a light chain variable region comprising the amino acid sequence of SEQ ID NO: 27 of WO 2011/066389 (SEQ ID NO:919). 
     In an embodiment, the targeting moiety comprises the anti-PD-L1 antibody 2.20A8, or fragments thereof, as disclosed in WO 2011/066389, U.S. Pat. No. 8,779,108, and US2014/0356353, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, 2.20A8 or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 32 of WO 2011/066389 (SEQ ID NO:920); and/or a light chain variable region comprising the amino acid sequence of SEQ ID NO: 37 of WO 2011/066389 (SEQ ID NO:921). 
     In an embodiment, the targeting moiety comprises the anti-PD-L1 antibody 3.15G8, or fragments thereof, as disclosed in WO 2011/066389, U.S. Pat. No. 8,779,108, and US2014/0356353, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, 3.15G8 or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 42 of WO 2011/066389 (SEQ ID NO:922); and/or a light chain variable region comprising the amino acid sequence of SEQ ID NO:923. 
     In an embodiment, the targeting moiety comprises the anti-PD-L1 antibody 3.18G1, or fragments thereof, as disclosed in WO 2011/066389, U.S. Pat. No. 8,779,108, and US2014/0356353, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, 3.18G1 or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 52 of WO 2011/066389 (SEQ ID NO:924); and/or a light chain variable region comprising the amino acid sequence of SEQ ID NO: 57 of WO 2011/066389 (SEQ ID NO:925). 
     In an embodiment, the targeting moiety comprises the anti-PD-L1 antibody 2.7A40PT, or fragments thereof, as disclosed in WO 2011/066389, U.S. Pat. No. 8,779,108, and US2014/0356353, and US2014/0356353, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, 2.7A40PT or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 62 of WO 2011/066389 (SEQ ID NO:926); and/or a light chain variable region comprising the amino acid sequence of SEQ ID NO: 67 of WO 2011/066389 (SEQ ID NO:927). 
     In an embodiment, the targeting moiety comprises the anti-PD-L1 antibody 2.14H90PT, or fragments thereof, as disclosed in WO 2011/066389, U.S. Pat. No. 8,779,108, and US2014/0356353, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, 2.14H90PT or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 72 of WO 2011/066389 (SEQ ID NO:928); and/or a light chain variable region comprising the amino acid sequence of SEQ ID NO: 77 of WO 2011/066389 (SEQ ID NO:929). 
     In an embodiment, the targeting moiety comprises any one of the anti-PD-L1 antibodies disclosed in WO2016/061142, the entire contents of which are hereby incorporated by reference. In illustrative embodiments, the antibody or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain comprising an amino acid sequence selected from SEQ ID NOs: 18, 30, 38, 46, 50, 54, 62, 70, and 78 of WO2016/061142: SEQ ID NO: 18 of WO2016/061142 (SEQ ID NO:930); SEQ ID NO: 30 of WO2016/061142 (SEQ ID NO:931); SEQ ID NO: 38 of WO2016/061142 (SEQ ID NO:932); SEQ ID NO: 46 of WO2016/061142 (SEQ ID NO:933); SEQ ID NO: 50 of WO2016/061142 (SEQ ID NO:934); SEQ ID NO: 54 of WO2016/061142 (SEQ ID NO:935); SEQ ID NO: 62 of WO2016/061142 (SEQ ID NO:936); SEQ ID NO: 70 of WO2016/061142 (SEQ ID NO:937); SEQ ID NO: 78 of WO2016/061142 (SEQ ID NO:938); and/or a light chain comprising an amino acid sequence selected from SEQ ID NOs: 22, 26, 34, 42, 58, 66, 74, 82, and 86 of WO2016/061142: SEQ ID NO: 22 of WO2016/061142 (SEQ ID NO:939); SEQ ID NO: 26 of WO2016/061142 (SEQ ID NO:940); SEQ ID NO: 34 of WO2016/061142 (SEQ ID NO:941); SEQ ID NO: 42 of WO2016/061142 (SEQ ID NO:942); SEQ ID NO: 58 of WO2016/061142 (SEQ ID NO:943); SEQ ID NO: 66 of WO2016/061142 (SEQ ID NO:944); SEQ ID NO: 74 of WO2016/061142 (SEQ ID NO:945); SEQ ID NO: 82 of WO2016/061142 (SEQ ID NO:946); or SEQ ID NO: 86 of WO2016/061142 (SEQ ID NO:947). 
     In an embodiment, the targeting moiety comprises any one of the anti-PD-L1 antibodies disclosed in WO2016/022630, the entire contents of which are hereby incorporated by reference. In illustrative embodiments, the antibody or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain comprising an amino acid sequence selected from SEQ ID NOs: 2, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, and 46 of WO2016/022630: SEQ ID NO: 2 of WO2016/022630 (SEQ ID NO:948); SEQ ID NO: 6 of WO2016/022630 (SEQ ID NO:949); SEQ ID NO: 10 of WO2016/022630 (SEQ ID NO:950); SEQ ID NO: 14 of WO2016/022630 (SEQ ID NO:951); SEQ ID NO: 18 of WO2016/022630 (SEQ ID NO:952); SEQ ID NO: 22 of WO2016/022630 (SEQ ID NO:953); SEQ ID NO: 26 of WO2016/022630 (SEQ ID NO:954); SEQ ID NO: 30 of WO2016/022630 (SEQ ID NO:955); SEQ ID NO: 34 of WO2016/022630 (SEQ ID NO:956); SEQ ID NO: 38 of WO2016/022630 (SEQ ID NO:957); SEQ ID NO: 42 of WO2016/022630 (SEQ ID NO:958); or SEQ ID NO: 46 of WO2016/022630 (SEQ ID NO:959); and/or a light chain comprising an amino acid sequence selected from SEQ ID NOs: 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, and 48 of WO2016/022630: SEQ ID NO: 4 of WO2016/022630 (SEQ ID NO:960); SEQ ID NO: 8 of WO2016/022630 (SEQ ID NO:961); SEQ ID NO: 12 of WO2016/022630 (SEQ ID NO:962); SEQ ID NO: 16 of WO2016/022630 (SEQ ID NO:963); SEQ ID NO: 20 of WO2016/022630 (SEQ ID NO:964); SEQ ID NO: 24 of WO2016/022630 (SEQ ID NO:965); SEQ ID NO: 28 of WO2016/022630 (SEQ ID NO:966); SEQ ID NO: 32 of WO2016/022630 (SEQ ID NO:967); SEQ ID NO: 36 of WO2016/022630 (SEQ ID NO:968); SEQ ID NO: 40 of WO2016/022630 (SEQ ID NO:969); SEQ ID NO: 44 of WO2016/022630 (SEQ ID NO:970); or SEQ ID NO: 48 of WO2016/022630 (SEQ ID NO:971). 
     In an embodiment, the targeting moiety comprises any one of the anti-PD-L1 antibodies disclosed in WO2015/112900, the entire contents of which are hereby incorporated by reference. In illustrative embodiments, the antibody or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain comprising an amino acid sequence selected from SEQ ID NOs: 38, 50, 82, and 86 of WO 2015/112900: SEQ ID NO: 38 of WO2015/112900 (SEQ ID NO:972); SEQ ID NO: 50 of WO 2015/112900 (SEQ ID NO:973); SEQ ID NO: 82 of WO 2015/112900 (SEQ ID NO:974); or SEQ ID NO: 86 of WO 2015/112900 (SEQ ID NO:975); and/or a light chain comprising an amino acid sequence selected from SEQ ID NOs: 42, 46, 54, 58, 62, 66, 70, 74, and 78 of WO 2015/112900: SEQ ID NO: 42 of WO2015/112900 (SEQ ID NO:976); SEQ ID NO: 46 of WO 2015/112900 (SEQ ID NO:977); SEQ ID NO: 54 of WO 2015/112900 (SEQ ID NO:978); SEQ ID NO: 58 of WO 2015/112900 (SEQ ID NO:979); SEQ ID NO: 62 of WO 2015/112900 (SEQ ID NO:980); SEQ ID NO: 66 of WO 2015/112900 (SEQ ID NO:981); SEQ ID NO: 70 of WO 2015/112900 (SEQ ID NO:982); SEQ ID NO: 74 of WO 2015/112900 (SEQ ID NO:983); SEQ ID NO: 78 of WO 2015/112900 (SEQ ID NO:984). 
     In an embodiment, the targeting moiety comprises any one of the anti-PD-L1 antibodies disclosed in WO 2010/077634 and U.S. Pat. No. 8,217,149, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, the anti-PD-L1 antibody or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain region comprising the amino acid sequence of: SEQ ID NO: 20 of WO 2010/077634 (SEQ ID NO:985); and/or a light chain variable region comprising the amino acid sequence of SEQ ID NO: 21 of WO 2010/077634 (SEQ ID NO:986). 
     In an embodiment, the targeting moiety comprises any one of the anti-PD-L1 antibodies obtainable from the hybridoma accessible under CNCM deposit numbers CNCM I-4122, CNCM I-4080 and CNCM I-4081 as disclosed in US 20120039906, the entire disclosures of which are hereby incorporated by reference. 
     In an embodiment, the targeting moiety comprises a VHH directed against PD-L1 as disclosed, for example, in U.S. Pat. No. 8,907,065 and WO 2008/071447, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, the VHHs against PD-L1 comprise SEQ ID NOS: 394-399 of U.S. Pat. No. 8,907,065: SEQ ID NO: 394 of U.S. Pat. No. 8,907,065 (SEQ ID NO:987); SEQ ID NO: 395 of U.S. Pat. No. 8,907,065 (SEQ ID NO:988); SEQ ID NO: 396 of U.S. Pat. No. 8,907,065 (SEQ ID NO:989); SEQ ID NO: 397 of U.S. Pat. No. 8,907,065 (SEQ ID NO:990); SEQ ID NO: 398 of U.S. Pat. No. 8,907,065 (SEQ ID NO:991); or SEQ ID NO: 399 of U.S. Pat. No. 8,907,065 (SEQ ID NO:992). 
     In various embodiments, the present multi-specific CD8 binding agent has one or more targeting moieties directed against PD-L2. In some embodiments, the CD8 binding agent has one or more targeting moieties which selectively bind a PD-L2 polypeptide. In some embodiments, the CD8 binding agent comprises one or more antibodies, antibody derivatives or formats, peptides or polypeptides, or fusion proteins that selectively bind a PD-L2 polypeptide. 
     In an embodiment, the targeting moiety comprises a VHH directed against PD-L2 as disclosed, for example, in U.S. Pat. No. 8,907,065 and WO 2008/071447, the entire disclosures of which are hereby incorporated by reference. In illustrative embodiments, the VHHs against PD-1 comprise SEQ ID NOs: 449-455 of U.S. Pat. No. 8,907,065: SEQ ID NO: 449 of U.S. Pat. No. 8,907,065 (SEQ ID NO:993); SEQ ID NO: 450 of U.S. Pat. No. 8,907,065 (SEQ ID NO:994); SEQ ID NO: 451 of U.S. Pat. No. 8,907,065 (SEQ ID NO:995); SEQ ID NO: 452 of U.S. Pat. No. 8,907,065 (SEQ ID NO:996); SEQ ID NO: 453 of U.S. Pat. No. 8,907,065 (SEQ ID NO:997); SEQ ID NO: 454 of U.S. Pat. No. 8,907,065 (SEQ ID NO:998); SEQ ID NO: 455 of U.S. Pat. No. 8,907,065 (SEQ ID NO:999). 
     In an embodiment, the targeting moiety comprises any one of the anti-PD-L2 antibodies disclosed in US2011/0271358 and WO2010/036959, the entire contents of which are hereby incorporated by reference. In illustrative embodiments, the antibody or an antigen-binding fragment thereof for use in the methods provided herein comprises a heavy chain comprising an amino acid sequence selected from SEQ ID NOs: 43-47 of US2011/0271358: SEQ ID NO: 43 of US2011/0271358 (SEQ ID NO:1000); SEQ ID NO: 44 of US2011/0271358 (SEQ ID NO:1001); SEQ ID NO: 45 of US2011/0271358 (SEQ ID NO:1002); SEQ ID NO: 46 of US2011/0271358 (SEQ ID NO:1003); SEQ ID NO: 47 of US2011/0271358 (SEQ ID NO:1004); and/or a light chain comprising an amino acid sequence selected from SEQ ID NOs: 48-51 of US2011/0271358: SEQ ID NO: 48 of US2011/0271358 (SEQ ID NO:1005); SEQ ID NO: 49 of US2011/0271358 (SEQ ID NO:1006); SEQ ID NO: 50 of US2011/0271358 (SEQ ID NO:1007); or SEQ ID NO: 51 of US2011/0271358 (SEQ ID NO:1008). 
     In various embodiments, the targeting moieties of the invention may comprise a sequence that targets PD-1, PD-L1, and/or PD-L2 which is at least about 60%, at least about 61%, at least about 62%, at least about 63%, at least about 64%, at least about 65%, at least about 66%, at least about 67%, at least about 68%, at least about 69%, at least about 70%, at least about 71%, at least about 72%, at least about 73%, at least about 74%, at least about 75%, at least about 76%, at least about 77%, at least about 78%, at least about 79%, at least about 80%, at least about 81%, at least about 82%, at least about 83%, at least about 84%, at least about 85%, at least about 86%, at least about 87%, at least about 88%, at least about 89%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or 100% identical to any of the sequences disclosed herein (e.g. about 60%, or about 61%, or about 62%, or about 63%, or about 64%, or about 65%, or about 66%, or about 67%, or about 68%, or about 69%, or about 70%, or about 71%, or about 72%, or about 73%, or about 74%, or about 75%, or about 76%, or about 77%, or about 78%, or about 79%, or about 80%, or about 81%, or about 82%, or about 83%, or about 84%, or about 85%, or about 86%, or about 87%, or about 88%, or about 89%, or about 90%, or about 91%, or about 92%, or about 93%, or about 94%, or about 95%, or about 96%, or about 97%, or about 98%, about 99% or about 100% sequence identity with any of the sequences disclosed herein). 
     In various embodiments, the targeting moieties of the invention may comprise any combination of heavy chain, light chain, heavy chain variable region, light chain variable region, complementarity determining region (CDR), and framework region sequences that target PD-1, PD-L1, and/or PD-L2 as disclosed herein. 
     Additional antibodies, antibody derivatives or formats, peptides or polypeptides, or fusion proteins that selectively bind or target PD-1, PD-L1 and/or PD-L2 are disclosed in WO 2011/066389, US 2008/0025980, US 2013/0034559, U.S. Pat. No. 8,779,108, US 2014/0356353, U.S. Pat. No. 8,609,089, US 2010/028330, US 2012/0114649, WO 2010/027827, WO 2011,/066342, U.S. Pat. No. 8,907,065, WO 2016/062722, WO 2009/101611, WO2010/027827, WO 2011/066342, WO 2007/005874, WO 2001/014556, US2011/0271358, WO 2010/036959, WO 2010/077634, U.S. Pat. No. 8,217,149, US 2012/0039906, WO 2012/145493, US 2011/0318373, U.S. Pat. No. 8,779,108, US 20140044738, WO 2009/089149, WO 2007/00587, WO 2016061142, WO 2016,02263, WO 2010/077634, and WO 2015/112900, the entire disclosures of which are hereby incorporated by reference. 
     In various embodiments, the multi-specific CD8 binding agent of the invention comprises a targeting moiety having an antigen recognition domain that specifically binds to XCR1, e.g. on DCs. In various embodiments, the multi-specific CD8 binding agent of the invention comprises a targeting moiety having an antigen recognition domain that comprise all of or part of XCL1. 
     In various embodiments, the multi-specific CD8 binding agents have targeting moieties having recognition domains which specifically bind to a target (e.g. antigen, receptor) which is part of a non-cellular structure. In some embodiments, the antigen or receptor is not an integral component of an intact cell or cellular structure. In some embodiments, the antigen or receptor is an extracellular antigen or receptor. In some embodiments, the target is a non-proteinaceous, non-cellular marker, including, without limitation, nucleic acids, inclusive of DNA or RNA, such as, for example, DNA released from necrotic tumor cells or extracellular deposits such as cholesterol. 
     In some embodiments, the target (e.g. antigen, receptor) of interest is part of the non-cellular component of the stroma or the extracellular matrix (ECM) or the markers associated therewith. As used herein, stroma refers to the connective and supportive framework of a tissue or organ. Stroma may include a compilation of cells such as fibroblasts/myofibroblasts, glial, epithelia, fat, immune, vascular, smooth muscle, and immune cells along with the extracellular matrix (ECM) and extracellular molecules. In various embodiments, the target (e.g. antigen, receptor) of interest is part of the non-cellular component of the stroma such as the extracellular matrix and extracellular molecules. As used herein, the ECM refers to the non-cellular components present within all tissues and organs. 
     The ECM is composed of a large collection of biochemically distinct components including, without limitation, proteins, glycoproteins, proteoglycans, and polysaccharides. These components of the ECM are usually produced by adjacent cells and secreted into the ECM via exocytosis. Once secreted, the ECM components often aggregate to form a complex network of macromolecules. In various embodiments, the chimeric protein of the invention comprises a targeting moiety that recognizes a target (e.g., an antigen or receptor or non-proteinaceous molecule) located on any component of the ECM. Illustrative components of the ECM include, without limitation, the proteoglycans, the non-proteoglycan polysaccharides, fibers, and other ECM proteins or ECM non-proteins, e.g. polysaccharides and/or lipids, or ECM associated molecules (e.g. proteins or non-proteins, e.g. polysaccharides, nucleic acids and/or lipids). 
     In some embodiments, the targeting moiety recognizes a target (e.g. antigen, receptor) on ECM proteoglycans. Proteoglycans are glycosylated proteins. The basic proteoglycan unit includes a core protein with one or more covalently attached glycosaminoglycan (GAG) chains. Proteoglycans have a net negative charge that attracts positively charged sodium ions (Na+), which attracts water molecules via osmosis, keeping the ECM and resident cells hydrated. Proteoglycans may also help to trap and store growth factors within the ECM. Illustrative proteoglycans that may be targeted by the chimeric proteins of the invention include, but are not limited to, heparan sulfate, chondroitin sulfate, and keratan sulfate. In an embodiment, the targeting moiety recognizes a target (e.g. antigen, receptor) on non-proteoglycan polysaccharides such as hyaluronic acid. 
     In some embodiments, the targeting moiety recognizes a target (e.g. antigen, receptor) on ECM fibers. ECM fibers include collagen fibers and elastin fibers. In some embodiments, the targeting moiety recognizes one or more epitopes on collagens or collagen fibers. Collagens are the most abundant proteins in the ECM. Collagens are present in the ECM as fibrillar proteins and provide structural support to resident cells. In one or more embodiments, the targeting moiety recognizes and binds to various types of collagens present within the ECM including, without limitation, fibrillar collagens (types I, II, III, V, XI), facit collagens (types IX, XII, XIV), short chain collagens (types VIII, X), basement membrane collagens (type IV), and/or collagen types VI, VII, or XIII. Elastin fibers provide elasticity to tissues, allowing them to stretch when needed and then return to their original state. In some embodiments, the target moiety recognizes one or more epitopes on elastins or elastin fibers. 
     In some embodiments, the targeting moiety recognizes one or more ECM proteins including, but not limited to, a tenascin, a fibronectin, a fibrin, a laminin, or a nidogen/entactin. 
     In an embodiment, the targeting moiety recognizes and binds to tenascin. The tenascin (TN) family of glycoproteins includes at least four members, tenascin-C, tenascin-R, tenascin-X, and tenascin W. The primary structures of tenascin proteins include several common motifs ordered in the same consecutive sequence: amino-terminal heptad repeats, epidermal growth factor (EGF)-like repeats, fibronectin type Ill domain repeats, and a carboxyl-terminal fibrinogen-like globular domain. Each protein member is associated with typical variations in the number and nature of EGF-like and fibronectin type Ill repeats. Isoform variants also exist particularly with respect to tenascin-C. Over 27 splice variants and/or isoforms of tenascin-C are known. In a particular embodiment, the targeting moiety recognizes and binds to tenascin-CA1. Similarly, tenascin-R also has various splice variants and isoforms. Tenascin-R usually exists as dimers or trimers. Tenascin-X is the largest member of the tenascin family and is known to exist as trimers. Tenascin-W exists as trimers. In some embodiments, the targeting moiety recognizes one or more epitopes on a tenascin protein. In some embodiments, the targeting moiety recognizes the monomeric and/or the dimeric and/or the trimeric and/or the hexameric forms of a tenascin protein. 
     In an embodiment, the targeting moieties recognize and bind to fibronectin. Fibronectins are glycoproteins that connect cells with collagen fibers in the ECM, allowing cells to move through the ECM. Upon binding to integrins, fibronectins unfolds to form functional dimers. In some embodiments, the targeting moiety recognizes the monomeric and/or the dimeric forms of fibronectin. In some embodiments, the targeting moiety recognizes one or more epitopes on fibronectin. In illustrative embodiments, the targeting moiety recognizes fibronectin extracellular domain A (EDA) or fibronectin extracellular domain B (EDB). Elevated levels of EDA are associated with various diseases and disorders including psoriasis, rheumatoid arthritis, diabetes, and cancer. In some embodiments, the targeting moiety recognizes fibronectin that contains the EDA isoform and may be utilized to target the chimeric protein to diseased cells including cancer cells. In some embodiments, the targeting moiety recognizes fibronectin that contains the EDB isoform. In various embodiments, such targeting moieties may be utilized to target the chimeric protein to tumor cells including the tumor neovasculature. 
     In an embodiment, the targeting moiety recognizes and binds to fibrin. Fibrin is another protein substance often found in the matrix network of the ECM. Fibrin is formed by the action of the protease thrombin on fibrinogen which causes the fibrin to polymerize. In some embodiments, the targeting moiety recognizes one or more epitopes on fibrin. In some embodiments, the targeting moiety recognizes the monomeric as well as the polymerized forms of fibrin. 
     In an embodiment, the targeting moiety recognizes and binds to laminin. Laminin is a major component of the basal lamina, which is a protein network foundation for cells and organs. Laminins are heterotrimeric proteins that contain an α-chain, a β-chain, and a γ-chain. In some embodiments, the targeting moiety recognizes one or more epitopes on laminin. In some embodiments, the targeting moiety recognizes the monomeric, the dimeric as well as the trimeric forms of laminin. 
     In an embodiment, the targeting moiety recognizes and binds to a nidogen or entactin. Nidogens/entactins are a family of highly conserved, sulfated glycoproteins. They make up the major structural component of the basement membranes and function to link laminin and collagen IV networks in basement membranes. Members of this family include nidogen-1 and nidogen-2. In various embodiments, the targeting moiety recognizes an epitope on nidogen-1 and/or nidogen-2. 
     In various embodiments, the targeting moiety comprises an antigen recognition domain that recognizes an epitope present on any of the targets (e.g., ECM proteins) described herein. In an embodiment, the antigen-recognition domain recognizes one or more linear epitopes present on the protein. As used herein, a linear epitope refers to any continuous sequence of amino acids present on the protein. In another embodiment, the antigen-recognition domain recognizes one or more conformational epitopes present on the protein. As used herein, a conformation epitope refers to one or more sections of amino acids (which may be discontinuous) which form a three-dimensional surface with features and/or shapes and/or tertiary structures capable of being recognized by an antigen recognition domain. 
     In various embodiments, the targeting moiety may bind to the full-length and/or mature forms and/or isoforms and/or splice variants and/or fragments and/or any other naturally occurring or synthetic analogs, variants, or mutants of any of the targets (e.g., ECM proteins) described herein. In various embodiments, the targeting moiety may bind to any forms of the proteins described herein, including monomeric, dimeric, trimeric, tetrameric, heterodimeric, multimeric and associated forms. In various embodiments, the targeting moiety may bind to any post-translationally modified forms of the proteins described herein, such as glycosylated and/or phosphorylated forms. 
     In various embodiments, the targeting moiety comprises an antigen recognition domain that recognizes extracellular molecules such as DNA. In some embodiments, the targeting moiety comprises an antigen recognition domain that recognizes DNA. In an embodiment, the DNA is shed into the extracellular space from necrotic or apoptotic tumor cells or other diseased cells. 
     In various embodiments, the targeting moiety comprises an antigen recognition domain that recognizes one or more non-cellular structures associated with atherosclerotic plaques. Two types of atherosclerotic plaques are known. The fibro-lipid (fibro-fatty) plaque is characterized by an accumulation of lipid-laden cells underneath the intima of the arteries. Beneath the endothelium there is a fibrous cap covering the atheromatous core of the plaque. 
     The core includes lipid-laden cells (macrophages and smooth muscle cells) with elevated tissue cholesterol and cholesterol ester content, fibrin, proteoglycans, collagen, elastin, and cellular debris. In advanced plaques, the central core of the plaque usually contains extracellular cholesterol deposits (released from dead cells), which form areas of cholesterol crystals with empty, needle-like clefts. At the periphery of the plaque are younger foamy cells and capillaries. A fibrous plaque is also localized under the intima, within the wall of the artery resulting in thickening and expansion of the wall and, sometimes, spotty localized narrowing of the lumen with some atrophy of the muscular layer. The fibrous plaque contains collagen fibers (eosinophilic), precipitates of calcium (hematoxylinophilic) and lipid-laden cells. In some embodiments, the targeting moiety recognizes and binds to one or more of the non-cellular components of these plaques such as the fibrin, proteoglycans, collagen, elastin, cellular debris, and calcium or other mineral deposits or precipitates. In some embodiments, the cellular debris is a nucleic acid, e.g. DNA or RNA, released from dead cells. 
     In various embodiments, the targeting moiety comprises an antigen recognition domain that recognizes one or more non-cellular structures found in the brain plaques associated with neurodegenerative diseases. In some embodiments, the targeting moiety recognizes and binds to one or more non-cellular structures located in the amyloid plaques found in the brains of patients with Alzheimer&#39;s disease. For example, the targeting moiety may recognize and bind to the peptide amyloid beta, which is a major component of the amyloid plaques. In some embodiments, the targeting moiety recognizes and binds to one or more non-cellular structures located in the brains plaques found in patients with Huntington&#39;s disease. In various embodiments, the targeting moiety recognizes and binds to one or more non-cellular structures found in plaques associated with other neurodegenerative or musculoskeletal diseases such as Lewy body dementia and inclusion body myositis. 
     Linkers and Functional Groups 
     In various embodiments, the CD8 binding agent may include one or more functional groups, residues, or moieties. In various embodiments, the one or more functional groups, residues, or moieties are attached or genetically fused to any of the signaling agents or targeting moieties described herein. In some embodiments, such functional groups, residues or moieties confer one or more desired properties or functionalities to the CD8 binding agent of the invention. Examples of such functional groups and of techniques for introducing them into the CD8 binding agent are known in the art, for example, see Remington&#39;s Pharmaceutical Sciences, 16th ed., Mack Publishing Co., Easton, Pa. (1980). 
     In various embodiments, the CD8 binding agent may by conjugated and/or fused with another agent to extend half-life or otherwise improve pharmacodynamic and pharmacokinetic properties. In some embodiments, the CD8 binding agent may be fused or conjugated with one or more of PEG, XTEN (e.g., as rPEG), polysialic acid (POLYXEN), albumin (e.g., human serum albumin or HAS), elastin-like protein (ELP), PAS, HAP, GLK, CTP, transferrin, and the like. In some embodiments, the CD8 binding agent may be fused or conjugated with an antibody or an antibody fragment such as an Fc fragment. For example, the chimeric protein may be fused to either the N-terminus or the C-terminus of the Fc domain of human immunoglobulin (Ig) G. In various embodiments, each of the individual chimeric proteins is fused to one or more of the agents described in BioDrugs (2015) 29:215-239, the entire contents of which are hereby incorporated by reference. 
     In some embodiments, the functional groups, residues, or moieties comprise a suitable pharmacologically acceptable polymer, such as poly(ethyleneglycol) (PEG) or derivatives thereof (such as methoxypoly(ethyleneglycol) or mPEG). In some embodiments, attachment of the PEG moiety increases the half-life and/or reduces the immunogenecity of the CD8 binding protein. Generally, any suitable form of pegylation can be used, such as the pegylation used in the art for antibodies and antibody fragments (including but not limited to single domain antibodies such as VHHs); see, for example, Chapman, Nat. Biotechnol., 54, 531-545 (2002); by Veronese and Harris, Adv. Drug Deliv. Rev. 54, 453-456 (2003), by Harris and Chess, Nat. Rev. Drug. Discov., 2, (2003) and in WO 04060965, the entire contents of which are hereby incorporated by reference. Various reagents for pegylation of proteins are also commercially available, for example, from Nektar Therapeutics, USA. In some embodiments, site-directed pegylation is used, in particular via a cysteine-residue (see, for example, Yang et al., Protein Engineering, 16, 10, 761-770 (2003), the entire contents of which is hereby incorporated by reference). For example, for this purpose, PEG may be attached to a cysteine residue that naturally occurs in the CD8 binding agent of the invention. In some embodiments, the CD8 binding agent of the invention is modified so as to suitably introduce one or more cysteine residues for attachment of PEG, or an amino acid sequence comprising one or more cysteine residues for attachment of PEG may be fused to the amino- and/or carboxy-terminus of the CD8 binding agent, using techniques known in the art. In some embodiments, the functional groups, residues, or moieties comprise N-linked or O-linked glycosylation. In some embodiments, the N-linked or O-linked glycosylation is introduced as part of a co-translational and/or post-translational modification. 
     In some embodiments, the functional groups, residues, or moieties comprise one or more detectable labels or other signal-generating groups or moieties. Suitable labels and techniques for attaching, using and detecting them are known in the art and, include, but are not limited to, fluorescent labels (such as fluorescein, isothiocyanate, rhodamine, phycoerythrin, phycocyanin, allophycocyanin, o-phthaldehyde, and fluorescamine and fluorescent metals such as Eu or others metals from the lanthanide series), phosphorescent labels, chemiluminescent labels or bioluminescent labels (such as luminal, isoluminol, theromatic acridinium ester, imidazole, acridinium salts, oxalate ester, dioxetane or GFP and its analogs), radio-isotopes, metals, metals chelates or metallic cations or other metals or metallic cations that are particularly suited for use in in vivo, in vitro or in situ diagnosis and imaging, as well as chromophores and enzymes (such as malate dehydrogenase, staphylococcal nuclease, delta-V-steroid isomerase, yeast alcohol dehydrogenase, alpha-glycerophosphate dehydrogenase, triose phosphate isomerase, biotinavidin peroxidase, horseradish peroxidase, alkaline phosphatase, asparaginase, glucose oxidase, beta-galactosidase, ribonuclease, urease, catalase, glucose-VI-phosphate dehydrogenase, glucoamylase and acetylcholine esterase). Other suitable labels include moieties that can be detected using NMR or ESR spectroscopy. Such labeled VHHs and polypeptides of the invention may, for example, be used for in vitro, in vivo or in situ assays (including immunoassays known per se such as ELISA, RIA, EIA and other “sandwich assays,” etc.) as well as in vivo diagnostic and imaging purposes, depending on the choice of the specific label. 
     In some embodiments, the functional groups, residues, or moieties comprise a tag that is attached or genetically fused to the CD8 binding agent. In some embodiments, the CD8 binding agent may include a single tag or multiple tags. The tag for example is a peptide, sugar, or DNA molecule that does not inhibit or prevent binding of the CD8 binding agent to CD8 or any other antigen of interest such as tumor antigens. In various embodiments, the tag is at least about: three to five amino acids long, five to eight amino acids long, eight to twelve amino acids long, twelve to fifteen amino acids long, or fifteen to twenty amino acids long. Exemplary tags are described for example, in U.S. Patent Publication No. US2013/0058962. In some embodiment, the tag is an affinity tag such as glutathione-S-transferase (GST) and histidine (His) tag. In an embodiment, the CD8 binding agent comprises a His tag. 
     In some embodiments, the functional groups, residues, or moieties comprise a chelating group, for example, to chelate one of the metals or metallic cations. Suitable chelating groups, for example, include, without limitation, diethyl-enetriaminepentaacetic acid (DTPA) or ethylenediaminetetraacetic acid (EDTA). 
     In some embodiments, the functional groups, residues, or moieties comprise a functional group that is one part of a specific binding pair, such as the biotin-(strept)avidin binding pair. Such a functional group may be used to link the CD8 binding agent of the invention to another protein, polypeptide or chemical compound that is bound to the other half of the binding pair, i.e., through formation of the binding pair. For example, a CD8 binding agent of the invention may be conjugated to biotin, and linked to another protein, polypeptide, compound or carrier conjugated to avidin or streptavidin. For example, such a conjugated CD8 binding agent may be used as a reporter, for example, in a diagnostic system where a detectable signal-producing agent is conjugated to avidin or streptavidin. 
     Such binding pairs may, for example, also be used to bind the CD8 binding agent to a carrier, including carriers suitable for pharmaceutical purposes. One non-limiting example are the liposomal formulations described by Cao and Suresh,  Journal of Drug Targeting,  8, 4, 257 (2000). Such binding pairs may also be used to link a therapeutically active agent to the CD8 binding agent of the invention. 
     In some embodiments, the present CD8 binding agent optionally comprises one or more linkers. In some embodiments, the present CD8 binding agent comprises a linker connecting the targeting moiety and the signaling agent. In some embodiments, the present chimeric protein comprises a linker within the signaling agent (e.g. in the case of single chain TNF, which can comprise two linkers to yield a trimer). 
     In some embodiments, the CD8 binding agent includes a linker that connects each binding region and/or targeting moieties. In some embodiments, the linker may be utilized to link various functional groups, residues, or moieties as described herein to the CD8 binding agent. In some embodiments, the linker is a single amino acid or a plurality of amino acids that does not affect or reduce the stability, orientation, binding, neutralization, and/or clearance characteristics of the binding regions and the binding protein. In various embodiments, the linker is selected from a peptide, a protein, a sugar, or a nucleic acid. 
     The invention contemplates the use of a variety of linker sequences. In various embodiments, the linker may be derived from naturally-occurring multi-domain proteins or are empirical linkers as described, for example, in Chichili et al., (2013), Protein Sci. 22(2):153-167, Chen et al., (2013), Adv Drug Deliv Rev. 65(10):1357-1369, the entire contents of which are hereby incorporated by reference. In some embodiments, the linker may be designed using linker designing databases and computer programs such as those described in Chen et al., (2013), Adv Drug Deliv Rev. 65(10):1357-1369 and Crasto et al., (2000), Protein Eng. 13(5):309-312, the entire contents of which are hereby incorporated by reference. In various embodiments, the linker may be functional. For example, without limitation, the linker may function to improve the folding and/or stability, improve the expression, improve the pharmacokinetics, and/or improve the bioactivity of the present CD8 binding agent. 
     In some embodiments, the linker is a polypeptide. In some embodiments, the linker is less than about 100 amino acids long. For example, the linker may be less than about 100, about 95, about 90, about 85, about 80, about 75, about 70, about 65, about 60, about 55, about 50, about 45, about 40, about 35, about 30, about 25, about 20, about 19, about 18, about 17, about 16, about 15, about 14, about 13, about 12, about 11, about 10, about 9, about 8, about 7, about 6, about 5, about 4, about 3, or about 2 amino acids long. In some embodiments, the e is flexible. In another embodiment, the linker is rigid. 
     In some embodiments, the linker is a polypeptide. In some embodiments, the linker is greater than about 100 amino acids long. For example, the linker may be greater than about 100, about 95, about 90, about 85, about 80, about 75, about 70, about 65, about 60, about 55, about 50, about 45, about 40, about 35, about 30, about 25, about 20, about 19, about 18, about 17, about 16, about 15, about 14, about 13, about 12, about 11, about 10, about 9, about 8, about 7, about 6, about 5, about 4, about 3, or about 2 amino acids long. In some embodiments, the linker is flexible. In another embodiment, the linker is rigid. 
     In various embodiments, the linker is substantially comprised of glycine and serine residues (e.g. about 30%, or about 40%, or about 50%, or about 60%, or about 70%, or about 80%, or about 90%, or about 95%, or about 97% glycines and serines). For example, in some embodiments, the linker is (Gly 4 Ser) n , where n is from about 1 to about 8, e.g. 1, 2, 3, 4, 5, 6, 7, or 8 (SEQ ID NOs: 1009-1016). In an embodiment, the linker sequence is GGSGGSGGGGSGGGGS (SEQ ID NO:1017). Additional illustrative linkers include, but are not limited to, linkers having the sequence LE, GGGGS (SEQ ID NO:1009), (GGGGS) n (n=1-4) (SEQ ID NOs:1009-1012), (Gly) 8 (SEQ ID NO:1018), (Gly) 6  (SEQ ID NO:1019), (EAAAK) n  (n=1-3) (SEQ ID NOs:1020-1022), A(EAAAK) n A (n=2-5) (SEQ ID NOs:1023-1026), AEAAAKEAAAKA (SEQ ID NO:1027), A(EAAAK) 4 ALEA(EAAAK) 4 A (SEQ ID NO:1028), PAPAP (SEQ ID NO:1029), KESGSVSSEQLAQFRSLD (SEQ ID NO:1030), EGKSSGSGSESKST (SEQ ID NO:1031), GSAGSAAGSGEF (SEQ ID NO:1032), and (XP) n , with X designating any amino acid, e.g., Ala, Lys, or Glu. In various embodiments, the linker is (GGS)n (n=1-20) (SEQ ID NO: 1176-SEQ ID NO: 1195). In some embodiments, the linker is G. In some embodiments, the linker is AAA. In some embodiments, the linker is (GGGGS)n (n=9-20) (SEQ ID NO: 1196-SEQ ID NO: 1207). 
     In some embodiments, the linker is one or more of GGGSE (SEQ ID NO: 1208), GSESG (SEQ ID NO: 1209), GSEGS (SEQ ID NO: 1210), GEGGSGEGSSGEGSSSEGGGSEGGGSEGGGSEGGS (SEQ ID NO: 1211), and a linker of randomly placed G, S, and E every 4 amino acid intervals. 
     In some embodiments, the linker is a hinge region of an antibody (e.g., of IgG, IgA, IgD, and IgE, inclusive of subclasses (e.g. IgG1, IgG2, IgG3, and IgG4, and IgA1 and IgA2)). In various embodiments, the linker is a hinge region of an antibody (e.g., of IgG, IgA, IgD, and IgE, inclusive of subclasses (e.g. IgG1, IgG2, IgG3, and IgG4, and IgA1 and IgA2)). The hinge region, found in IgG, IgA, IgD, and IgE class antibodies, acts as a flexible spacer, allowing the Fab portion to move freely in space. In contrast to the constant regions, the hinge domains are structurally diverse, varying in both sequence and length among immunoglobulin classes and subclasses. For example, the length and flexibility of the hinge region varies among the IgG subclasses. The hinge region of IgG1 encompasses amino acids 216-231 and, because it is freely flexible, the Fab fragments can rotate about their axes of symmetry and move within a sphere centered at the first of two inter-heavy chain disulfide bridges. IgG2 has a shorter hinge than IgG1, with 12 amino acid residues and four disulfide bridges. The hinge region of IgG2 lacks a glycine residue, is relatively short, and contains a rigid poly-proline double helix, stabilized by extra inter-heavy chain disulfide bridges. These properties restrict the flexibility of the IgG2 molecule. IgG3 differs from the other subclasses by its unique extended hinge region (about four times as long as the IgG1 hinge), containing 62 amino acids (including 21 prolines and 11 cysteines), forming an inflexible poly-proline double helix. In IgG3, the Fab fragments are relatively far away from the Fc fragment, giving the molecule a greater flexibility. The elongated hinge in IgG3 is also responsible for its higher molecular weight compared to the other subclasses. The hinge region of IgG4 is shorter than that of IgG1 and its flexibility is intermediate between that of IgG1 and IgG2. The flexibility of the hinge regions reportedly decreases in the order IgG3&gt;IgG1&gt;IgG4&gt;IgG2. 
     According to crystallographic studies, the immunoglobulin hinge region can be further subdivided functionally into three regions: the upper hinge region, the core region, and the lower hinge region. See Shin et al., 1992 Immunological Reviews 130:87. The upper hinge region includes amino acids from the carboxyl end of C H 1 to the first residue in the hinge that restricts motion, generally the first cysteine residue that forms an interchain disulfide bond between the two heavy chains. The length of the upper hinge region correlates with the segmental flexibility of the antibody. The core hinge region contains the inter-heavy chain disulfide bridges, and the lower hinge region joins the amino terminal end of the C H2  domain and includes residues in C H2 . Id. The core hinge region of wild-type human IgG1 contains the sequence Cys-Pro-Pro-Cys (SEQ ID NO: 1212) which, when dimerized by disulfide bond formation, results in a cyclic octapeptide believed to act as a pivot, thus conferring flexibility. In various embodiments, the present linker comprises, one, or two, or three of the upper hinge region, the core region, and the lower hinge region of any antibody (e.g., of IgG, IgA, IgD, and IgE, inclusive of subclasses (e.g. IgG1, IgG2, IgG3, and IgG4, and IgA1 and IgA2)). The hinge region may also contain one or more glycosylation sites, which include a number of structurally distinct types of sites for carbohydrate attachment. For example, IgA1 contains five glycosylation sites within a 17-amino-acid segment of the hinge region, conferring resistance of the hinge region polypeptide to intestinal proteases, considered an advantageous property for a secretory immunoglobulin. 
     In various embodiments, the linker of the present invention comprises one or more glycosylation sites. In various embodiments, the linker is a hinge-CH2-CH3 domain of a human IgG4 antibody. 
     If desired, the present CD8 binding agent can be linked to an antibody Fc region, comprising one or both of C H2  and C H3  domains, and optionally a hinge region. For example, vectors encoding the present CD8 binding agents linked as a single nucleotide sequence to an Fc region can be used to prepare such polypeptides. 
     In some embodiments, the linker is a synthetic linker such as PEG. 
     In various embodiments, the linker may be functional. For example, without limitation, the linker may function to improve the folding and/or stability, improve the expression, improve the pharmacokinetics, and/or improve the bioactivity of the present CD8 binding agent. In another example, the linker may function to target the CD8 binding agent to a particular cell type or location. 
     Modifications and Production of CD8 Binding Agents 
     In various embodiments, the CD8 binding agent comprises a targeting moiety that is a VHH. In various embodiments, the VHH is not limited to a specific biological source or to a specific method of preparation. For example, the VHH can generally be obtained: (1) by isolating the V H H domain of a naturally occurring heavy chain antibody; (2) by expression of a nucleotide sequence encoding a naturally occurring V H H domain; (3) by “humanization” of a naturally occurring V H H domain or by expression of a nucleic acid encoding a such humanized V H H domain; (4) by “camelization” of a naturally occurring VH domain from any animal species, such as from a mammalian species, such as from a human being, or by expression of a nucleic acid encoding such a camelized VH domain; (5) by “camelization” of a “domain antibody” or “Dab” as described in the art, or by expression of a nucleic acid encoding such a camelized VH domain; (6) by using synthetic or semi-synthetic techniques for preparing proteins, polypeptides or other amino acid sequences known in the art; (7) by preparing a nucleic acid encoding a VHH using techniques for nucleic acid synthesis known in the art, followed by expression of the nucleic acid thus obtained; and/or (8) by any combination of one or more of the foregoing. 
     In an embodiment, the CD8 binding agent comprises a VHH that corresponds to the V H H domains of naturally occurring heavy chain antibodies directed against human CD8. In some embodiments, such V H H sequences can generally be generated or obtained by suitably immunizing a species of Camelid with a CD8 molecule, (i.e., so as to raise an immune response and/or heavy chain antibodies directed against CD8), by obtaining a suitable biological sample from the Camelid (such as a blood sample, or any sample of B-cells), and by generating V H H sequences directed against CD8, starting from the sample, using any suitable known techniques. In some embodiments, naturally occurring V H H domains against CD8 can be obtained from naive libraries of Camelid V H H sequences, for example, by screening such a library using CD8 or at least one part, fragment, antigenic determinant or epitope thereof using one or more screening techniques known in the art. Such libraries and techniques are, for example, described in WO9937681, WO0190190, WO03025020 and WO03035694, the entire contents of which are hereby incorporated by reference. In some embodiments, improved synthetic or semi-synthetic libraries derived from naive V H H libraries may be used, such as V H H libraries obtained from naive V H H libraries by techniques such as random mutagenesis and/or CDR shuffling, as for example, described in WO0043507, the entire contents of which are hereby incorporated by reference. In some embodiments, another technique for obtaining V H H sequences directed against a CD8 involves suitably immunizing a transgenic mammal that is capable of expressing heavy chain antibodies (i.e., so as to raise an immune response and/or heavy chain antibodies directed against CD8), obtaining a suitable biological sample from the transgenic mammal (such as a blood sample, or any sample of B-cells), and then generating V H H sequences directed against CD8 starting from the sample, using any suitable known techniques. For example, for this purpose, the heavy chain antibody-expressing mice and the further methods and techniques described in WO02085945 and in WO04049794 (the entire contents of which are hereby incorporated by reference) can be used. 
     In an embodiment, the CD8 binding agent comprises a VHH that has been “humanized” i.e., by replacing one or more amino acid residues in the amino acid sequence of the naturally occurring V H H sequence (and in particular in the framework sequences) by one or more of the amino acid residues that occur at the corresponding position(s) in a VH domain from a conventional 4-chain antibody from a human being. This can be performed using humanization techniques known in the art. In some embodiments, possible humanizing substitutions or combinations of humanizing substitutions may be determined by methods known in the art, for example, by a comparison between the sequence of a VHH and the sequence of a naturally occurring human VH domain. In some embodiments, the humanizing substitutions are chosen such that the resulting humanized VHHs still retain advantageous functional properties. Generally, as a result of humanization, the VH Hs of the invention may become more “human-like,” while still retaining favorable properties such as a reduced immunogenicity, compared to the corresponding naturally occurring V H H domains. In various embodiments, the humanized VHHs of the invention can be obtained in any suitable manner known in the art and thus are not strictly limited to polypeptides that have been obtained using a polypeptide that comprises a naturally occurring V H H domain as a starting material. 
     In an embodiment, the CD8 binding agent comprises a VHH that has been “camelized,” i.e., by replacing one or more amino acid residues in the amino acid sequence of a naturally occurring VH domain from a conventional 4-chain antibody by one or more of the amino acid residues that occur at the corresponding position(s) in a V H H domain of a heavy chain antibody of a camelid. In some embodiments, such “camelizing” substitutions are inserted at amino acid positions that form and/or are present at the VH-VL interface, and/or at the so-called Camelidae hallmark residues (see, for example, WO9404678, the entire contents of which are hereby incorporated by reference). In some embodiments, the VH sequence that is used as a starting material or starting point for generating or designing the camelized VHH is a VH sequence from a mammal, for example, the VH sequence of a human being, such as a VH3 sequence. In various embodiments, the camelized VHHs can be obtained in any suitable manner known in the art (i.e., as indicated under points (1)-(8) above) and thus are not strictly limited to polypeptides that have been obtained using a polypeptide that comprises a naturally occurring VH domain as a starting material. 
     In various embodiments, both “humanization” and “camelization” can be performed by providing a nucleotide sequence that encodes a naturally occurring V H H domain or VH domain, respectively, and then changing, in a manner known in the art, one or more codons in the nucleotide sequence in such a way that the new nucleotide sequence encodes a “humanized” or “camelized” VHH, respectively. This nucleic acid can then be expressed in a manner known in the art, so as to provide the desired VHH of the invention. Alternatively, based on the amino acid sequence of a naturally occurring V H H domain or VH domain, respectively, the amino acid sequence of the desired humanized or camelized VHH of the invention, respectively, can be designed and then synthesized de novo using techniques for peptide synthesis known in the art. Also, based on the amino acid sequence or nucleotide sequence of a naturally occurring V H H domain or VH domain, respectively, a nucleotide sequence encoding the desired humanized or camelized VHH, respectively, can be designed and then synthesized de novo using techniques for nucleic acid synthesis known in the art, after which the nucleic acid thus obtained can be expressed in a manner known in the art, so as to provide the desired VHH of the invention. Other suitable methods and techniques for obtaining the VHHs of the invention and/or nucleic acids encoding the same, starting from naturally occurring VH sequences or V H H sequences, are known in the art, and may, for example, comprise combining one or more parts of one or more naturally occurring VH sequences (such as one or more FR sequences and/or CDR sequences), one or more parts of one or more naturally occurring V H H sequences (such as one or more FR sequences or CDR sequences), and/or one or more synthetic or semi-synthetic sequences, in a suitable manner, so as to provide a VHH of the invention or a nucleotide sequence or nucleic acid encoding the same. 
     Methods for producing the CD8 binding agents of the invention are described herein. For example, DNA sequences encoding the CD8 binding agents of the invention can be chemically synthesized using methods known in the art. Synthetic DNA sequences can be ligated to other appropriate nucleotide sequences, including, e.g., expression control sequences, to produce gene expression constructs encoding the desired CD8 binding agents. Accordingly, in various embodiments, the present invention provides for isolated nucleic acids comprising a nucleotide sequence encoding the CD8 binding agent of the invention. 
     Nucleic acids encoding the CD8 binding agent of the invention can be incorporated (ligated) into expression vectors, which can be introduced into host cells through transfection, transformation, or transduction techniques. For example, nucleic acids encoding the CD8 binding agent of the invention can be introduced into host cells by retroviral transduction. Illustrative host cells are  E. coli  cells, Chinese hamster ovary (CHO) cells, human embryonic kidney 293 (HEK 293) cells, HeLa cells, baby hamster kidney (BHK) cells, monkey kidney cells (COS), human hepatocellular carcinoma cells (e.g., Hep G2), and myeloma cells. Transformed host cells can be grown under conditions that permit the host cells to express the genes that encode the CD8 binding agent of the invention. Accordingly, in various embodiments, the present invention provides expression vectors comprising nucleic acids that encode the CD8 binding agent of the invention. In various embodiments, the present invention additional provides host cells comprising such expression vectors. 
     Specific expression and purification conditions will vary depending upon the expression system employed. For example, if a gene is to be expressed in  E. coli , it is first cloned into an expression vector by positioning the engineered gene downstream from a suitable bacterial promoter, e.g., Trp or Tac, and a prokaryotic signal sequence. In another example, if the engineered gene is to be expressed in eukaryotic host cells, e.g., CHO cells, it is first inserted into an expression vector containing for example, a suitable eukaryotic promoter, a secretion signal, enhancers, and various introns. The gene construct can be introduced into the host cells using transfection, transformation, or transduction techniques. 
     The CD8 binding agent of the invention can be produced by growing a host cell transfected with an expression vector encoding the CD8 binding agent under conditions that permit expression of the protein. Following expression, the protein can be harvested and purified using techniques well known in the art, e.g., affinity tags such as glutathione-S-transferase (GST) and histidine (His) tags or by chromatography. In an embodiment, the CD8 binding agent comprises a His tag (which is optionally cleavable via an engineered proteolytic cleavage site). 
     Accordingly, in various embodiments, the present invention provides for a nucleic acid encoding a CD8 binding agent of the present invention. In various embodiments, the present invention provides for a host cell comprising a nucleic acid encoding a CD8 binding agent of the present invention. 
     In various embodiments, the present CD8 binding agent or chimeric protein comprising the same may be expressed in vivo, for instance, in a patient. For example, in various embodiments, the present CD8 binding agent or chimeric protein comprising the same may administered in the form of nucleic acid which encodes the present CD8 binding agents or chimeric proteins comprising the same. In various embodiments, the nucleic acid is DNA or RNA. In some embodiments, present CD8 binding agent or chimeric protein comprising the same is encoded by a modified mRNA, i.e. an mRNA comprising one or more modified nucleotides. In some embodiments, the modified mRNA comprises one or modifications found in U.S. Pat. No. 8,278,036, the entire contents of which are hereby incorporated by reference. In some embodiments, the modified mRNA comprises one or more of m5C, m5U, m6A, s2U, Ψ, and 2′-O-methyl-U. In some embodiments, the present invention relates to administering a modified mRNA encoding one or more of the present chimeric proteins. In some embodiments, the present invention relates to gene therapy vectors comprising the same. In some embodiments, the present invention relates to gene therapy methods comprising the same. In various embodiments, the nucleic acid is in the form of an oncolytic virus, e.g. an adenovirus, reovirus, measles, herpes simplex, Newcastle disease virus or vaccinia. 
     Pharmaceutically Acceptable Salts and Excipients 
     The CD8 binding agents described herein can possess a sufficiently basic functional group, which can react with an inorganic or organic acid, or a carboxyl group, which can react with an inorganic or organic base, to form a pharmaceutically acceptable salt. A pharmaceutically acceptable acid addition salt is formed from a pharmaceutically acceptable acid, as is well known in the art. Such salts include the pharmaceutically acceptable salts listed in, for example,  Journal of Pharmaceutical Science,  66, 2-19 (1977) and  The Handbook of Pharmaceutical Salts; Properties, Selection , and Use. P. H. Stahl and C. G. Wermuth (eds.), Verlag, Zurich (Switzerland) 2002, which are hereby incorporated by reference in their entirety. 
     Pharmaceutically acceptable salts include, by way of non-limiting example, sulfate, citrate, acetate, oxalate, chloride, bromide, iodide, nitrate, bisulfate, phosphate, acid phosphate, isonicotinate, lactate, salicylate, acid citrate, tartrate, oleate, tannate, pantothenate, bitartrate, ascorbate, succinate, maleate, gentisinate, fumarate, gluconate, glucaronate, saccharate, formate, benzoate, glutamate, methanesulfonate, ethanesulfonate, benzenesulfonate, p-toluenesulfonate, camphorsulfonate, pamoate, phenylacetate, trifluoroacetate, acrylate, chlorobenzoate, dinitrobenzoate, hydroxybenzoate, methoxybenzoate, methylbenzoate, o-acetoxybenzoate, naphthalene-2-benzoate, isobutyrate, phenylbutyrate, α-hydroxybutyrate, butyne-1,4-dicarboxylate, hexyne-1,4-dicarboxylate, caprate, caprylate, cinnamate, glycollate, heptanoate, hippurate, malate, hydroxymaleate, malonate, mandelate, mesylate, nicotinate, phthalate, teraphthalate, propiolate, propionate, phenylpropionate, sebacate, suberate, p-bromobenzenesulfonate, chlorobenzenesulfonate, ethylsulfonate, 2-hydroxyethylsulfonate, methylsulfonate, naphthalene-1-sulfonate, naphthalene-2-sulfonate, naphthalene-1,5-sulfonate, xylenesulfonate, and tartarate salts. 
     The term “pharmaceutically acceptable salt” also refers to a salt of the compositions of the present invention having an acidic functional group, such as a carboxylic acid functional group, and a base. Suitable bases include, but are not limited to, hydroxides of alkali metals such as sodium, potassium, and lithium; hydroxides of alkaline earth metal such as calcium and magnesium; hydroxides of other metals, such as aluminum and zinc; ammonia, and organic amines, such as unsubstituted or hydroxy-substituted mono-, di-, or tri-alkylamines, dicyclohexylamine; tributyl amine; pyridine; N-methyl, N-ethylamine; diethylamine; triethylamine; mono-, bis-, or tris-(2-OH-lower alkylamines), such as mono-; bis-, or tris-(2-hydroxyethyl)amine, 2-hydroxy-tert-butylamine, or tris-(hydroxymethyl)methylamine, N,N-di-lower alkyl-N-(hydroxyl-lower alkyl)-amines, such as N,N-dimethyl-N-(2-hydroxyethyl)amine or tri-(2-hydroxyethyl)amine; N-methyl-D-glucamine; and amino acids such as arginine, lysine, and the like. 
     In some embodiments, the compositions described herein are in the form of a pharmaceutically acceptable salt. 
     Pharmaceutical Compositions and Formulations 
     In various embodiments, the present invention pertains to pharmaceutical compositions comprising the CD8 binding agents described herein and a pharmaceutically acceptable carrier or excipient. Any pharmaceutical compositions described herein can be administered to a subject as a component of a composition that comprises a pharmaceutically acceptable carrier or vehicle. Such compositions can optionally comprise a suitable amount of a pharmaceutically acceptable excipient so as to provide the form for proper administration. 
     In various embodiments, pharmaceutical excipients can be liquids, such as water and oils, including those of petroleum, animal, vegetable, or synthetic origin, such as peanut oil, soybean oil, mineral oil, sesame oil and the like. The pharmaceutical excipients can be, for example, saline, gum acacia, gelatin, starch paste, talc, keratin, colloidal silica, urea and the like. In addition, auxiliary, stabilizing, thickening, lubricating, and coloring agents can be used. In one embodiment, the pharmaceutically acceptable excipients are sterile when administered to a subject. Water is a useful excipient when any agent described herein is administered intravenously. Saline solutions and aqueous dextrose and glycerol solutions can also be employed as liquid excipients, specifically for injectable solutions. Suitable pharmaceutical excipients also include starch, glucose, lactose, sucrose, gelatin, malt, rice, flour, chalk, silica gel, sodium stearate, glycerol monostearate, talc, sodium chloride, dried skim milk, glycerol, propylene, glycol, water, ethanol and the like. Any agent described herein, if desired, can also comprise minor amounts of wetting or emulsifying agents, or pH buffering agents. Other examples of suitable pharmaceutical excipients are described in Remington&#39;s Pharmaceutical Sciences 1447-1676 (Alfonso R. Gennaro eds., 19th ed. 1995), incorporated herein by reference. 
     The present invention includes the described pharmaceutical compositions (and/or additional therapeutic agents) in various formulations. Any inventive pharmaceutical composition (and/or additional therapeutic agents) described herein can take the form of solutions, suspensions, emulsion, drops, tablets, pills, pellets, capsules, capsules containing liquids, gelatin capsules, powders, sustained-release formulations, suppositories, emulsions, aerosols, sprays, suspensions, lyophilized powder, frozen suspension, dessicated powder, or any other form suitable for use. In one embodiment, the composition is in the form of a capsule. In another embodiment, the composition is in the form of a tablet. In yet another embodiment, the pharmaceutical composition is formulated in the form of a soft-gel capsule. In a further embodiment, the pharmaceutical composition is formulated in the form of a gelatin capsule. In yet another embodiment, the pharmaceutical composition is formulated as a liquid. 
     Where necessary, the inventive pharmaceutical compositions (and/or additional agents) can also include a solubilizing agent. Also, the agents can be delivered with a suitable vehicle or delivery device as known in the art. Combination therapies outlined herein can be co-delivered in a single delivery vehicle or delivery device. 
     The formulations comprising the inventive pharmaceutical compositions (and/or additional agents) of the present invention may conveniently be presented in unit dosage forms and may be prepared by any of the methods well known in the art of pharmacy. Such methods generally include the step of bringing the therapeutic agents into association with a carrier, which constitutes one or more accessory ingredients. Typically, the formulations are prepared by uniformly and intimately bringing the therapeutic agent into association with a liquid carrier, a finely divided solid carrier, or both, and then, if necessary, shaping the product into dosage forms of the desired formulation (e.g., wet or dry granulation, powder blends, etc., followed by tableting using conventional methods known in the art). 
     In various embodiments, any pharmaceutical compositions (and/or additional agents) described herein is formulated in accordance with routine procedures as a composition adapted for a mode of administration described herein. 
     Routes of administration include, for example: oral, intradermal, intramuscular, intraperitoneal, intravenous, subcutaneous, intranasal, epidural, sublingual, intranasal, intracerebral, intravaginal, transdermal, rectally, by inhalation, or topically. Administration can be local or systemic. In some embodiments, the administering is effected orally. In another embodiment, the administration is by parenteral injection. The mode of administration can be left to the discretion of the practitioner, and depends in-part upon the site of the medical condition. In most instances, administration results in the release of any agent described herein into the bloodstream. 
     In one embodiment, the CD8 binding agent described herein is formulated in accordance with routine procedures as a composition adapted for oral administration. Compositions for oral delivery can be in the form of tablets, lozenges, aqueous or oily suspensions, granules, powders, emulsions, capsules, syrups, or elixirs, for example. Orally administered compositions can comprise one or more agents, for example, sweetening agents such as fructose, aspartame or saccharin; flavoring agents such as peppermint, oil of wintergreen, or cherry; coloring agents; and preserving agents, to provide a pharmaceutically palatable preparation. Moreover, where in tablet or pill form, the compositions can be coated to delay disintegration and absorption in the gastrointestinal tract thereby providing a sustained action over an extended period of time. Selectively permeable membranes surrounding an osmotically active driving any CD8 binding agents described herein are also suitable for orally administered compositions. In these latter platforms, fluid from the environment surrounding the capsule is imbibed by the driving compound, which swells to displace the agent or agent composition through an aperture. These delivery platforms can provide an essentially zero order delivery profile as opposed to the spiked profiles of immediate release formulations. A time-delay material such as glycerol monostearate or glycerol stearate can also be useful. Oral compositions can include standard excipients such as mannitol, lactose, starch, magnesium stearate, sodium saccharin, cellulose, and magnesium carbonate. In one embodiment, the excipients are of pharmaceutical grade. Suspensions, in addition to the active compounds, may contain suspending agents such as, for example, ethoxylated isostearyl alcohols, polyoxyethylene sorbitol and sorbitan esters, microcrystalline cellulose, aluminum metahydroxide, bentonite, agar-agar, tragacanth, etc., and mixtures thereof. 
     Dosage forms suitable for parenteral administration (e.g. intravenous, intramuscular, intraperitoneal, subcutaneous and intra-articular injection and infusion) include, for example, solutions, suspensions, dispersions, emulsions, and the like. They may also be manufactured in the form of sterile solid compositions (e.g. lyophilized composition), which can be dissolved or suspended in sterile injectable medium immediately before use. They may contain, for example, suspending or dispersing agents known in the art. Formulation components suitable for parenteral administration include a sterile diluent such as water for injection, saline solution, fixed oils, polyethylene glycols, glycerine, propylene glycol or other synthetic solvents; antibacterial agents such as benzyl alcohol or methyl paraben; antioxidants such as ascorbic acid or sodium bisulfite; chelating agents such as EDTA; buffers such as acetates, citrates or phosphates; and agents for the adjustment of tonicity such as sodium chloride or dextrose. 
     For intravenous administration, suitable carriers include physiological saline, bacteriostatic water, Cremophor ELTM (BASF, Parsippany, N.J.) or phosphate buffered saline (PBS). The carrier should be stable under the conditions of manufacture and storage, and should be preserved against microorganisms. The carrier can be a solvent or dispersion medium containing, for example, water, ethanol, polyol (for example, glycerol, propylene glycol, and liquid polyetheylene glycol), and suitable mixtures thereof. 
     The compositions provided herein, alone or in combination with other suitable components, can be made into aerosol formulations (i.e., “nebulized”) to be administered via inhalation. Aerosol formulations can be placed into pressurized acceptable propellants, such as dichlorodifluoromethane, propane, nitrogen, and the like. 
     Any inventive pharmaceutical compositions (and/or additional agents) described herein can be administered by controlled-release or sustained-release means or by delivery devices that are well known to those of ordinary skill in the art. Examples include, but are not limited to, those described in U.S. Pat. Nos. 3,845,770; 3,916,899; 3,536,809; 3,598,123; 4,008,719; 5,674,533; 5,059,595; 5,591,767; 5,120,548; 5,073,543; 5,639,476; 5,354,556; and 5,733,556, each of which is incorporated herein by reference in its entirety. Such dosage forms can be useful for providing controlled- or sustained-release of one or more active ingredients using, for example, hydropropyl cellulose, hydropropylmethyl cellulose, polyvinylpyrrolidone, other polymer matrices, gels, permeable membranes, osmotic systems, multilayer coatings, microparticles, liposomes, microspheres, or a combination thereof to provide the desired release profile in varying proportions. Suitable controlled- or sustained-release formulations known to those skilled in the art, including those described herein, can be readily selected for use with the active ingredients of the agents described herein. The invention thus provides single unit dosage forms suitable for oral administration such as, but not limited to, tablets, capsules, gelcaps, and caplets that are adapted for controlled- or sustained-release. 
     Controlled- or sustained-release of an active ingredient can be stimulated by various conditions, including but not limited to, changes in pH, changes in temperature, stimulation by an appropriate wavelength of light, concentration or availability of enzymes, concentration or availability of water, or other physiological conditions or compounds. 
     In another embodiment, a controlled-release system can be placed in proximity of the target area to be treated, thus requiring only a fraction of the systemic dose (see, e.g., Goodson, in Medical Applications of Controlled Release, supra, vol. 2, pp. 115-138 (1984)). Other controlled-release systems discussed in the review by Langer, 1990, Science 249:1527-1533) may be used. 
     Pharmaceutical formulations preferably are sterile. Sterilization can be accomplished, for example, by filtration through sterile filtration membranes. Where the composition is lyophilized, filter sterilization can be conducted prior to or following lyophilization and reconstitution. 
     Administration and Dosage 
     It will be appreciated that the actual dose of the CD8 binding agent to be administered according to the present invention will vary according to the particular dosage form, and the mode of administration. Many factors that may modify the action of the CD8 binding agent (e.g., body weight, gender, diet, time of administration, route of administration, rate of excretion, condition of the subject, drug combinations, genetic disposition and reaction sensitivities) can be taken into account by those skilled in the art. Administration can be carried out continuously or in one or more discrete doses within the maximum tolerated dose. Optimal administration rates for a given set of conditions can be ascertained by those skilled in the art using conventional dosage administration tests. 
     In some embodiments, a suitable dosage of the CD8 binding agent is in a range of about 0.01 mg/kg to about 10 g/kg of body weight of the subject, about 0.01 mg/kg to about 1 g/kg of body weight of the subject, about 0.01 mg/kg to about 100 mg/kg of body weight of the subject, about 0.01 mg/kg to about 10 mg/kg of body weight of the subject, for example, about 0.01 mg/kg, about 0.02 mg/kg, about 0.03 mg/kg, about 0.04 mg/kg, about 0.05 mg/kg, about 0.06 mg/kg, about 0.07 mg/kg, about 0.08 mg/kg, about 0.09 mg/kg, about 0.1 mg/kg, about 0.2 mg/kg, about 0.3 mg/kg, about 0.4 mg/kg, about 0.5 mg/kg, about 0.6 mg/kg, about 0.7 mg/kg, about 0.8 mg/kg, about 0.9 mg/kg, about 1 mg/kg, about 1.1 mg/kg, about 1.2 mg/kg, about 1.3 mg/kg, about 1.4 mg/kg, about 1.5 mg/kg, about 1.6 mg/kg, about 1.7 mg/kg, about 1.8 mg/kg, 1.9 mg/kg, about 2 mg/kg, about 3 mg/kg, about 4 mg/kg, about 5 mg/kg, about 6 mg/kg, about 7 mg/kg, about 8 mg/kg, about 9 mg/kg, about 10 mg/kg body weight, about 100 mg/kg body weight, about 1 g/kg of body weight, about 10 g/kg of body weight, inclusive of all values and ranges therebetween. 
     Individual doses of the CD8 binding agent can be administered in unit dosage forms containing, for example, from about 0.01 mg to about 100 g, from about 0.01 mg to about 75 g, from about 0.01 mg to about 50 g, from about 0.01 mg to about 25 g, about 0.01 mg to about 10 g, about 0.01 mg to about 7.5 g, about 0.01 mg to about 5 g, about 0.01 mg to about 2.5 g, about 0.01 mg to about 1 g, about 0.01 mg to about 100 mg, from about 0.1 mg to about 100 mg, from about 0.1 mg to about 90 mg, from about 0.1 mg to about 80 mg, from about 0.1 mg to about 70 mg, from about 0.1 mg to about 60 mg, from about 0.1 mg to about 50 mg, from about 0.1 mg to about 40 mg active ingredient, from about 0.1 mg to about 30 mg, from about 0.1 mg to about 20 mg, from about 0.1 mg to about 10 mg, from about 0.1 mg to about 5 mg, from about 0.1 mg to about 3 mg, from about 0.1 mg to about 1 mg per unit dosage form, or from about 5 mg to about 80 mg per unit dosage form. For example, a unit dosage form can be about 0.01 mg, about 0.02 mg, about 0.03 mg, about 0.04 mg, about 0.05 mg, about 0.06 mg, about 0.07 mg, about 0.08 mg, about 0.09 mg, about 0.1 mg, about 0.2 mg, about 0.3 mg, about 0.4 mg, about 0.5 mg, about 0.6 mg, about 0.7 mg, about 0.8 mg, about 0.9 mg, about 1 mg, about 2 mg, about 3 mg, about 4 mg, about 5 mg, about 6 mg, about 7 mg, about 8 mg, about 9 mg about 10 mg, about 15 mg, about 20 mg, about 25 mg, about 30 mg, about 35 mg, about 40 mg, about 45 mg, about 50 mg, about 55 mg, about 60 mg, about 65 mg, about 70 mg, about 75 mg, about 80 mg, about 85 mg, about 90 mg, about 95 mg, about 100 mg, about 200 mg, about 500 mg, about 1 g, about 2.5 g, about 5 g, about 10 g, about 25 g, about 50 g, about 75 g, about 100 g, inclusive of all values and ranges therebetween. 
     In one embodiment, the CD8 binding agent is administered at an amount of from about 0.01 mg to about 100 g daily, from about 0.01 mg to about 75 g daily, from about 0.01 mg to about 50 g daily, from about 0.01 mg to about 25 g daily, from about 0.01 mg to about 10 g daily, from about 0.01 mg to about 7.5 g daily, from about 0.01 mg to about 5 g daily, from about 0.01 mg to about 2.5 g daily, from about 0.01 mg to about 1 g daily, from about 0.01 mg to about 100 mg daily, from about 0.1 mg to about 100 mg daily, from about 0.1 mg to about 95 mg daily, from about 0.1 mg to about 90 mg daily, from about 0.1 mg to about 85 mg daily, from about 0.1 mg to about 80 mg daily, from about 0.1 mg to about 75 mg daily, from about 0.1 mg to about 70 mg daily, from about 0.1 mg to about 65 mg daily, from about 0.1 mg to about 60 mg daily, from about 0.1 mg to about 55 mg daily, from about 0.1 mg to about 50 mg daily, from about 0.1 mg to about 45 mg daily, from about 0.1 mg to about 40 mg daily, from about 0.1 mg to about 35 mg daily, from about 0.1 mg to about 30 mg daily, from about 0.1 mg to about 25 mg daily, from about 0.1 mg to about 20 mg daily, from about 0.1 mg to about 15 mg daily, from about 0.1 mg to about 10 mg daily, from about 0.1 mg to about 5 mg daily, from about 0.1 mg to about 3 mg daily, from about 0.1 mg to about 1 mg daily, or from about 5 mg to about 80 mg daily. In various embodiments, the CD8 binding agent is administered at a daily dose of about 0.01 mg, about 0.02 mg, about 0.03 mg, about 0.04 mg, about 0.05 mg, about 0.06 mg, about 0.07 mg, about 0.08 mg, about 0.09 mg, about 0.1 mg, about 0.2 mg, about 0.3 mg, about 0.4 mg, about 0.5 mg, about 0.6 mg, about 0.7 mg, about 0.8 mg, about 0.9 mg, about 1 mg, about 2 mg, about 3 mg, about 4 mg, about 5 mg, about 6 mg, about 7 mg, about 8 mg, about 9 mg about 10 mg, about 15 mg, about 20 mg, about 25 mg, about 30 mg, about 35 mg, about 40 mg, about 45 mg, about 50 mg, about 55 mg, about 60 mg, about 65 mg, about 70 mg, about 75 mg, about 80 mg, about 85 mg, about 90 mg, about 95 mg, about 100 mg, about 200 mg, about 500 mg, about 1 g, about 2.5 g, about 5 g, about 7.5 g, about 10 g, about 25 g, about 50 g, about 75 g, about 100 g, inclusive of all values and ranges therebetween. 
     In accordance with certain embodiments of the invention, the pharmaceutical composition comprising the CD8 binding agent may be administered, for example, more than once daily (e.g., about two times, about three times, about four times, about five times, about six times, about seven times, about eight times, about nine times, or about ten times daily), about once per day, about every other day, about every third day, about once a week, about once every two weeks, about once every month, about once every two months, about once every three months, about once every six months, or about once every year. 
     Combination Therapy and Additional Therapeutic Agents 
     In various embodiments, the pharmaceutical composition of the present invention is co-administered in conjunction with additional therapeutic agent(s). Co-administration can be simultaneous or sequential. 
     In one embodiment, the additional therapeutic agent and the CD8 binding agent of the present invention are administered to a subject simultaneously. The term “simultaneously” as used herein, means that the additional therapeutic agent and the CD8 binding agent are administered with a time separation of no more than about 60 minutes, such as no more than about 30 minutes, no more than about 20 minutes, no more than about 10 minutes, no more than about 5 minutes, or no more than about 1 minute. Administration of the additional therapeutic agent and the CD8 binding agent can be by simultaneous administration of a single formulation (e.g., a formulation comprising the additional therapeutic agent and the CD8 binding agent) or of separate formulations (e.g., a first formulation including the additional therapeutic agent and a second formulation including the CD8 binding agent). 
     Co-administration does not require the therapeutic agents to be administered simultaneously, if the timing of their administration is such that the pharmacological activities of the additional therapeutic agent and the CD8 binding agent overlap in time, thereby exerting a combined therapeutic effect. For example, the additional therapeutic agent and the CD8 binding agent can be administered sequentially. The term “sequentially” as used herein means that the additional therapeutic agent and the CD8 binding agent are administered with a time separation of more than about 60 minutes. For example, the time between the sequential administration of the additional therapeutic agent and the CD8 binding agent can be more than about 60 minutes, more than about 2 hours, more than about 5 hours, more than about 10 hours, more than about 1 day, more than about 2 days, more than about 3 days, more than about 1 week apart, more than about 2 weeks apart, or more than about one month apart. The optimal administration times will depend on the rates of metabolism, excretion, and/or the pharmacodynamic activity of the additional therapeutic agent and the CD8 binding agent being administered. Either the additional therapeutic agent or the CD8 binding agent cell may be administered first. 
     Co-administration also does not require the therapeutic agents to be administered to the subject by the same route of administration. Rather, each therapeutic agent can be administered by any appropriate route, for example, parenterally or non-parenterally. 
     In some embodiments, the CD8 binding agent described herein acts synergistically when co-administered with another therapeutic agent. In such embodiments, the CD8 binding agent and the additional therapeutic agent may be administered at doses that are lower than the doses employed when the agents are used in the context of monotherapy. 
     In some embodiments, the present invention pertains to chemotherapeutic agents as additional therapeutic agents. For example, without limitation, such combination of the present CD8 binding agents and chemotherapeutic agent find use in the treatment of cancers, as described elsewhere herein. Examples of chemotherapeutic agents include, but are not limited to, alkylating agents such as thiotepa and CYTOXAN cyclosphosphamide; alkyl sulfonates such as busulfan, improsulfan and piposulfan; aziridines such as benzodopa, carboquone, meturedopa, and uredopa; ethylenimines and methylamelamines including altretamine, triethylenemelamine, trietylenephosphoramide, triethiylenethiophosphoramide and trimethylolomelamine; acetogenins (e.g., bullatacin and bullatacinone); a camptothecin (including the synthetic analogue topotecan); bryostatin; cally statin; CC-1065 (including its adozelesin, carzelesin and bizelesin synthetic analogues); cryptophycins (e.g., cryptophycin 1 and cryptophycin 8); dolastatin; duocarmycin (including the synthetic analogues, KW-2189 and CB 1-TM1); eleutherobin; pancratistatin; a sarcodictyin; spongistatin; nitrogen mustards such as chlorambucil, chlornaphazine, cholophosphamide, estramustine, ifosfamide, mechlorethamine, mechlorethamine oxide hydrochloride, melphalan, novembichin, phenesterine, prednimustine, trofosfamide, uracil mustard; nitrosureas such as carmustine, chlorozotocin, fotemustine, lomustine, nimustine, and ranimnustine; antibiotics such as the enediyne antibiotics (e.g., calicheamicin, especially calicheamicin gammall and calicheamicin omegall (see, e.g., Agnew, Chem. Intl. Ed. Engl., 33: 183-186 (1994)); dynemicin, including dynemicin A; bisphosphonates, such as clodronate; an esperamicin; as well as neocarzinostatin chromophore and related chromoprotein enediyne antibiotic chromophores), aclacinomysins, actinomycin, authramycin, azaserine, bleomycins, cactinomycin, carabicin, caminomycin, carzinophilin, chromomycinis, dactinomycin, daunorubicin, detorubicin, 6-diazo-5-oxo-L-norleucine, ADRIAMYCIN doxorubicin (including morpholino-doxorubicin, cyanomorpholino-doxorubicin, 2-pyrrolino-doxorubicin and deoxy doxorubicin), epirubicin, esorubicin, idarubicin, marcellomycin, mitomycins such as mitomycin C, mycophenolic acid, nogalamycin, olivomycins, peplomycin, potfiromycin, puromycin, quelamycin, rodorubicin, streptonigrin, streptozocin, tubercidin, ubenimex, zinostatin, zorubicin; anti-metabolites such as methotrexate and 5-fluorouracil (5-FU); folic acid analogues such as denopterin, methotrexate, pteropterin, trimetrexate; purine analogs such as fludarabine, 6-mercaptopurine, thiamiprine, thioguanine; pyrimidine analogs such as ancitabine, azacitidine, 6-azauridine, carmofur, cytarabine, dideoxyuridine, doxifluridine, enocitabine, floxuridine; androgens such as calusterone, dromostanolone propionate, epitiostanol, mepitiostane, testolactone; anti-adrenals such as minoglutethimide, mitotane, trilostane; folic acid replenisher such as frolinic acid; aceglatone; aldophosphamide glycoside; aminolevulinic acid; eniluracil; amsacrine; bestrabucil; bisantrene; edatraxate; demecolcine; diaziquone; elformithine; elliptinium acetate; an epothilone; etoglucid; gallium nitrate; hydroxyurea; lentinan; lonidainine; maytansinoids such as maytansine and ansamitocins; mitoguazone; mitoxantrone; mopidanmol; nitraerine; pentostatin; phenamet; pirarubicin; losoxantrone; podophyllinic acid; 2-ethylhydrazide; procarbazine; PSK polysaccharide complex (JHS Natural Products, Eugene, Oreg.); razoxane; rhizoxin; sizofuran; spirogermanium; tenuazonic acid; triaziquone; 2,2′,2″-trichlorotriethylamine; trichothecenes (e.g., T-2 toxin, verracurin A, roridin A and anguidine); urethan; vindesine; dacarbazine; mannomustine; mitobronitol; mitolactol; pipobroman; gacytosine; arabinoside (“Ara-C”); cyclophosphamide; thiotepa; taxoids, e.g., TAXOL paclitaxel (Bristol-Myers Squibb Oncology, Princeton, N.J.), ABRAXANE Cremophor-free, albumin-engineered nanoparticle formulation of paclitaxel (American Pharmaceutical Partners, Schaumberg, 111.), and TAXOTERE doxetaxel (Rhone-Poulenc Rorer, Antony, France); chloranbucil; GEMZAR gemcitabine; 6-thioguanine; mercaptopurine; methotrexate; platinum analogs such as cisplatin, oxaliplatin and carboplatin; vinblastine; platinum; etoposide (VP-16); ifosfamide; mitoxantrone; vincristine; NAVELBINE. vinorelbine; novantrone; teniposide; edatrexate; daunomycin; aminopterin; xeloda; ibandronate; irinotecan (Camptosar, CPT-11) (including the treatment regimen of irinotecan with 5-FU and leucovorin); topoisomerase inhibitor RFS 2000; difluoromethylornithine (DMFO); retinoids such as retinoic acid; capecitabine; combretastatin; leucovorin (LV); oxaliplatin, including the oxaliplatin treatment regimen (FOLFOX); lapatinib (Tykerb); inhibitors of PKC-α, Raf, H-Ras, EGFR (e.g., erlotinib (Tarceva)) and VEGF-A that reduce cell proliferation and pharmaceutically acceptable salts, acids or derivatives of any of the above. In addition, the methods of treatment can further include the use of radiation. In addition, the methods of treatment can further include the use of photodynamic therapy. 
     In some embodiments, inclusive of, without limitation, infectious disease applications, the present invention pertains to anti-infectives as additional therapeutic agents. In some embodiments, the anti-infective is an anti-viral agent including, but not limited to, Abacavir, Acyclovir, Adefovir, Amprenavir, Atazanavir, Cidofovir, Darunavir, Delavirdine, Didanosine, Docosanol, Efavirenz, Elvitegravir, Emtricitabine, Enfuvirtide, Etravirine, Famciclovir, and Foscarnet. In some embodiments, the anti-infective is an anti-bacterial agent including, but not limited to, cephalosporin antibiotics (cephalexin, cefuroxime, cefadroxil, cefazolin, cephalothin, cefaclor, cefamandole, cefoxitin, cefprozil, and ceftobiprole); fluoroquinolone antibiotics (cipro, Levaquin, floxin, tequin, avelox, and norflox); tetracycline antibiotics (tetracycline, minocycline, oxytetracycline, and doxycycline); penicillin antibiotics (amoxicillin, ampicillin, penicillin V, dicloxacillin, carbenicillin, vancomycin, and methicillin); monobactam antibiotics (aztreonam); and carbapenem antibiotics (ertapenem, doripenem, imipenem/cilastatin, and meropenem). In some embodiments, the anti-infectives include anti-malarial agents (e.g., chloroquine, quinine, mefloquine, primaquine, doxycycline, artemether/lumefantrine, atovaquone/proguanil and sulfadoxine/pyrimethamine), metronidazole, tinidazole, ivermectin, pyrantel pamoate, and albendazole. 
     In some embodiments, inclusive, without limitation, of autoimmmune applications, the additional therapeutic agent is an immunosuppressive agent. In some embodiments, the immunosuppressive agent is an anti-inflammatory agent such as a steroidal anti-inflammatory agent or a non-steroidal anti-inflammatory agent (NSAID). Steroids, particularly the adrenal corticosteroids and their synthetic analogues, are well known in the art. Examples of corticosteroids useful in the present invention include, without limitation, hydroxyltriamcinolone, alpha-methyl dexamethasone, beta-methyl betamethasone, beclomethasone dipropionate, betamethasone benzoate, betamethasone dipropionate, betamethasone valerate, clobetasol valerate, desonide, desoxymethasone, dexamethasone, diflorasone diacetate, diflucortolone valerate, fluadrenolone, fluclorolone acetonide, flumethasone pivalate, fluosinolone acetonide, fluocinonide, flucortine butylester, fluocortolone, fluprednidene (fluprednylidene) acetate, flurandrenolone, halcinonide, hydrocortisone acetate, hydrocortisone butyrate, methylprednisolone, triamcinolone acetonide, cortisone, cortodoxone, flucetonide, fludrocortisone, difluorosone diacetate, fluradrenolone acetonide, medrysone, amcinafel, amcinafide, betamethasone and the balance of its esters, chloroprednisone, clocortelone, clescinolone, dichlorisone, difluprednate, flucloronide, flunisolide, fluoromethalone, fluperolone, fluprednisolone, hydrocortisone, meprednisone, paramethasone, prednisolone, prednisone, beclomethasone dipropionate. (NSAIDS) that may be used in the present invention, include but are not limited to, salicylic acid, acetyl salicylic acid, methyl salicylate, glycol salicylate, salicylmides, benzyl-2,5-diacetoxybenzoic acid, ibuprofen, fulindac, naproxen, ketoprofen, etofenamate, phenylbutazone, and indomethacin. In some embodiments, the immunosupressive agent may be cytostatics such as alkylating agents, antimetabolites (e.g., azathioprine, methotrexate), cytotoxic antibiotics, antibodies (e.g., basiliximab, daclizumab, and muromonab), anti-immunophilins (e.g., cyclosporine, tacrolimus, sirolimus), inteferons, opioids, TNF binding proteins, mycophenolates, and small biological agents (e.g., fingolimod, myriocin). Additional anti-inflammatory agents are described, for example, in U.S. Pat. No. 4,537,776, the entire contents of which is incorporated by reference herein. 
     In some embodiments, the present invention relates to combination therapy with one or more immune-modulating agents, for example, without limitation, agents that modulate immune checkpoint. In various embodiments, the immune-modulating agent targets one or more of PD-1, PD-L1, and PD-L2. In various embodiments, the immune-modulating agent is PD-1 inhibitor. In various embodiments, the immune-modulating agent is an antibody specific for one or more of PD-1, PD-L1, and PD-L2. For instance, in some embodiments, the immune-modulating agent is an antibody such as, by way of non-limitation, nivolumab, (ONO-4538/BMS-936558, MDX1106, OPDIVO, BRISTOL MYERS SQUIBB), pembrolizumab (KEYTRUDA, MERCK), pidilizumab (CT-011, CURE TECH), MK-3475 (MERCK), BMS 936559 (BRISTOL MYERS SQUIBB), MPDL3280A (ROCHE). In some embodiments, the immune-modulating agent targets one or more of CD137 or CD137L. In various embodiments, the immune-modulating agent is an antibody specific for one or more of CD137 or CD137L. For instance, in some embodiments, the immune-modulating agent is an antibody such as, by way of non-limitation, urelumab (also known as BMS-663513 and anti-4-1BB antibody). In some embodiments, the present CD8 binding agent is combined with urelumab (optionally with one or more of nivolumab, lirilumab, and urelumab) for the treatment of solid tumors and/or B-cell non-Hodgkins lymphoma and/or head and neck cancer and/or multiple myeloma. In some embodiments, the immune-modulating agent is an agent that targets one or more of CTLA-4, AP2M1, CD80, CD86, SHP-2, and PPP2R5A. In various embodiments, the immune-modulating agent is an antibody specific for one or more of CTLA-4, AP2M1, CD80, CD86, SHP-2, and PPP2R5A. For instance, in some embodiments, the immune-modulating agent is an antibody such as, by way of non-limitation, ipilimumab (MDX-010, MDX-101, Yervoy, BMS) and/or tremelimumab (Pfizer). In some embodiments, the present CD8 binding agent is combined with ipilimumab (optionally with bavituximab) for the treatment of one or more of melanoma, prostate cancer, and lung cancer. In various embodiments, the immune-modulating agent targets CD20. In various embodiments, the immune-modulating agent is an antibody specific CD20. For instance, in some embodiments, the immune-modulating agent is an antibody such as, by way of non-limitation, Ofatumumab (GENMAB), obinutuzumab (GAZYVA), AME-133v (APPLIED MOLECULAR EVOLUTION), Ocrelizumab (GENENTECH), TRU-015 (TRUBION/EMERGENT), veltuzumab (IMMU-106). 
     In some embodiments, the present invention relates to combination therapy with one or more chimeric agents described in WO 2013/10779, WO 2015/007536, WO 2015/007520, WO 2015/007542, and WO 2015/007903, the entire contents of which are hereby incorporated by reference in their entireties. 
     In some embodiments, the CD8 binding agent described herein, include derivatives that are modified, i.e., by the covalent attachment of any type of molecule to the composition such that covalent attachment does not prevent the activity of the composition. For example, but not by way of limitation, derivatives include composition that have been modified by, inter alia, glycosylation, lipidation, acetylation, pegylation, phosphorylation, amidation, derivatization by known protecting/blocking groups, proteolytic cleavage, linkage to a cellular ligand or other protein, etc. Any of numerous chemical modifications can be carried out by known techniques, including, but not limited to specific chemical cleavage, acetylation, formylation, metabolic synthesis of tunicamycin, etc. 
     In still other embodiments, the CD8 binding agent described herein further comprise a cytotoxic agent, comprising, in illustrative embodiments, a toxin, a chemotherapeutic agent, a radioisotope, and an agent that causes apoptosis or cell death. Such agents may be conjugated to a composition described herein. 
     The CD8 binding agent described herein may thus be modified post-translationally to add effector moieties such as chemical linkers, detectable moieties such as for example fluorescent dyes, enzymes, substrates, bioluminescent materials, radioactive materials, and chemiluminescent moieties, or functional moieties such as for example streptavidin, avidin, biotin, a cytotoxin, a cytotoxic agent, and radioactive materials. 
     Illustrative cytotoxic agents include, but are not limited to, methotrexate, aminopterin, 6-mercaptopurine, 6-thioguanine, cytarabine, 5-fluorouracil decarbazine; alkylating agents such as mechlorethamine, thioepa chlorambucil, melphalan, carmustine (BSNU), mitomycin C, lomustine (CCNU), 1-methylnitrosourea, cyclothosphamide, mechlorethamine, busulfan, dibromomannitol, streptozotocin, mitomycin C, cis-dichlorodiamine platinum (II) (DDP) cisplatin and carboplatin (paraplatin); anthracyclines include daunorubicin (formerly daunomycin), doxorubicin (adriamycin), detorubicin, carminomycin, idarubicin, epirubicin, mitoxantrone and bisantrene; antibiotics include dactinomycin (actinomycin D), bleomycin, calicheamicin, mithramycin, and anthramycin (AMC); and antimytotic agents such as the vinca alkaloids, vincristine and vinblastine. Other cytotoxic agents include paclitaxel (taxol), ricin, pseudomonas exotoxin, gemcitabine, cytochalasin B, gramicidin D, ethidium bromide, emetine, etoposide, tenoposide, colchicin, dihydroxy anthracin dione, 1-dehydrotestosterone, glucocorticoids, procaine, tetracaine, lidocaine, propranolol, puromycin, procarbazine, hydroxyurea, asparaginase, corticosteroids, mytotane (O,P′-(DDD)), interferons, and mixtures of these cytotoxic agents. 
     Further cytotoxic agents include, but are not limited to, chemotherapeutic agents such as carboplatin, cisplatin, paclitaxel, gemcitabine, calicheamicin, doxorubicin, 5-fluorouracil, mitomycin C, actinomycin D, cyclophosphamide, vincristine, bleomycin, VEGF antagonists, EGFR antagonists, platins, taxols, irinotecan, 5-fluorouracil, gemcytabine, leucovorine, steroids, cyclophosphamide, melphalan, vinca alkaloids (e.g., vinblastine, vincristine, vindesine and vinorelbine), mustines, tyrosine kinase inhibitors, radiotherapy, sex hormone antagonists, selective androgen receptor modulators, selective estrogen receptor modulators, PDGF antagonists, TNF antagonists, IL-1 antagonists, interleukins (e.g. IL-12 or IL-2), IL-12R antagonists, Toxin conjugated monoclonal antibodies, tumor antigen specific monoclonal antibodies, Erbitux, Avastin, Pertuzumab, anti-CD20 antibodies, Rituxan, ocrelizumab, ofatumumab, DXL625, HERCEPTIN®, or any combination thereof. Toxic enzymes from plants and bacteria such as ricin, diphtheria toxin and Pseudomonas toxin may be conjugated to the therapeutic agents (e.g. antibodies) to generate cell-type-specific-killing reagents (Youle, et al., Proc. Nat&#39;l Acad. Sci. USA 77:5483 (1980); Gilliland, et al., Proc. Nat&#39;l Acad. Sci. USA 77:4539 (1980); Krolick, et al., Proc. Nat&#39;l Acad. Sci. USA 77:5419 (1980)). 
     Other cytotoxic agents include cytotoxic ribonucleases as described by Goldenberg in U.S. Pat. No. 6,653,104. Embodiments of the invention also relate to radioimmunoconjugates where a radionuclide that emits alpha or beta particles is stably coupled to the CD8 binding agent, with or without the use of a complex-forming agent. Such radionuclides include beta-emitters such as Phosphorus-32, Scandium-47, Copper-67, Gallium-67, Yttrium-88, Yttrium-90, Iodine-125, Iodine-131, Samarium-153, Lutetium-177, Rhenium-186 or Rhenium-188, and alpha-emitters such as Astatine-211, Lead-212, Bismuth-212, Bismuth-213 or Actinium-225. 
     Illustrative detectable moieties further include, but are not limited to, horseradish peroxidase, acetylcholinesterase, alkaline phosphatase, beta-galactosidase and luciferase. Further illustrative fluorescent materials include, but are not limited to, rhodamine, fluorescein, fluorescein isothiocyanate, umbelliferone, dichlorotriazinylamine, phycoerythrin and dansyl chloride. Further illustrative chemiluminescent moieties include, but are not limited to, luminol. Further illustrative bioluminescent materials include, but are not limited to, luciferin and aequorin. Further illustrative radioactive materials include, but are not limited to, lodine-125, Carbon-14, Sulfur-35, Tritium and Phosphorus-32. 
     Methods of Treatment 
     Methods and compositions described herein have application to treating various diseases and disorders, including, but not limited to cancer, infections, immune disorders, inflammatory diseases or conditions, and autoimmune diseases. 
     Further, any of the present agents may be for use in the treating, or the manufacture of a medicament for treating, various diseases and disorders, including, but not limited to cancer, infections, immune disorders, inflammatory diseases or conditions, and autoimmune diseases. 
     In some embodiments, the present invention relates to the treatment of, or a patient having cancer. As used herein, cancer refers to any uncontrolled growth of cells that may interfere with the normal functioning of the bodily organs and systems, and includes both primary and metastatic tumors. Primary tumors or cancers that migrate from their original location and seed vital organs can eventually lead to the death of the subject through the functional deterioration of the affected organs. A metastasis is a cancer cell or group of cancer cells, distinct from the primary tumor location, resulting from the dissemination of cancer cells from the primary tumor to other parts of the body. Metastases may eventually result in death of a subject. For example, cancers can include benign and malignant cancers, polyps, hyperplasia, as well as dormant tumors or micrometastases. 
     Illustrative cancers that may be treated include, but are not limited to, basal cell carcinoma, biliary tract cancer; bladder cancer; bone cancer; brain and central nervous system cancer; breast cancer; cancer of the peritoneum; cervical cancer; choriocarcinoma; colon and rectum cancer; connective tissue cancer; cancer of the digestive system; endometrial cancer; esophageal cancer; eye cancer; cancer of the head and neck; gastric cancer (including gastrointestinal cancer); glioblastoma; hepatic carcinoma; hepatoma; intra-epithelial neoplasm; kidney or renal cancer; larynx cancer; leukemia; liver cancer; lung cancer (e.g., small-cell lung cancer, non-small cell lung cancer, adenocarcinoma of the lung, and squamous carcinoma of the lung); melanoma; myeloma; neuroblastoma; oral cavity cancer (lip, tongue, mouth, and pharynx); ovarian cancer; pancreatic cancer; prostate cancer; retinoblastoma; rhabdomyosarcoma; rectal cancer; cancer of the respiratory system; salivary gland carcinoma; sarcoma; skin cancer; squamous cell cancer; stomach cancer; testicular cancer; thyroid cancer; uterine or endometrial cancer; cancer of the urinary system; vulval cancer; lymphoma including Hodgkin&#39;s and non-Hodgkin&#39;s lymphoma, as well as B-cell lymphoma (including low grade/follicular non-Hodgkin&#39;s lymphoma (NHL); small lymphocytic (SL) NHL; intermediate grade/follicular NHL; intermediate grade diffuse NHL; high grade immunoblastic NHL; high grade lymphoblastic NHL; high grade small non-cleaved cell NHL; bulky disease NHL; mantle cell lymphoma; AIDS-related lymphoma; and Waldenstrom&#39;s Macroglobulinemia; chronic lymphocytic leukemia (CLL); acute lymphoblastic leukemia (ALL); Hairy cell leukemia; chronic myeloblastic leukemia; as well as other carcinomas and sarcomas; and post-transplant lymphoproliferative disorder (PTLD), as well as abnormal vascular proliferation associated with phakomatoses, edema (e.g. that associated with brain tumors), and Meigs&#39; syndrome. 
     Illustrative cancers that may be treated include, but are not limited to, carcinomas, e.g. various subtypes, including, for example, adenocarcinoma, basal cell carcinoma, squamous cell carcinoma, and transitional cell carcinoma), sarcomas (including, for example, bone and soft tissue), leukemias (including, for example, acute myeloid, acute lymphoblastic, chronic myeloid, chronic lymphocytic, and hairy cell), lymphomas and myelomas (including, for example, Hodgkin and non-Hodgkin lymphomas, light chain, non-secretory, MGUS, and plasmacytomas), and central nervous system cancers (including, for example, brain (e.g. gliomas (e.g. astrocytoma, oligodendroglioma, and ependymoma), meningioma, pituitary adenoma, and neuromas, and spinal cord tumors (e.g. meningiomas and neurofibroma). 
     In some embodiments, the present invention relates to the treatment of, or a patient having a microbial infection and/or chronic infection. Illustrative infections include, but are not limited to, HIV/AIDS, tuberculosis, osteomyelitis, hepatitis B, hepatitis C, Epstein-Barr virus or parvovirus, T cell leukemia virus, bacterial overgrowth syndrome, fungal or parasitic infections. 
     In various embodiments, the present compositions are used to treat or prevent one or more inflammatory diseases or conditions, such as inflammation, acute inflammation, chronic inflammation, respiratory disease, atherosclerosis, restenosis, asthma, allergic rhinitis, atopic dermatitis, septic shock, rheumatoid arthritis, inflammatory bowel disease, inflammatory pelvic disease, pain, ocular inflammatory disease, celiac disease, Leigh Syndrome, Glycerol Kinase Deficiency, Familial eosinophilia (FE), autosomal recessive spastic ataxia, laryngeal inflammatory disease; Tuberculosis, Chronic cholecystitis, Bronchiectasis, Silicosis and other pneumoconioses. 
     In various embodiments, the present compositions are used to treat or prevent one or more autoimmune diseases or conditions, such as multiple sclerosis, diabetes mellitus, lupus, celiac disease, Crohn&#39;s disease, ulcerative colitis, Guillain-Barre syndrome, scleroderms, Goodpasture&#39;s syndrome, Wegener&#39;s granulomatosis, autoimmune epilepsy, Rasmussen&#39;s encephalitis, Primary biliary sclerosis, Sclerosing cholangitis, Autoimmune hepatitis, Addison&#39;s disease, Hashimoto&#39;s thyroiditis, Fibromyalgia, Menier&#39;s syndrome; transplantation rejection (e.g., prevention of allograft rejection) pernicious anemia, rheumatoid arthritis, systemic lupus erythematosus, dermatomyositis, Sjogren&#39;s syndrome, lupus erythematosus, multiple sclerosis, myasthenia gravis, Reiter&#39;s syndrome, Grave&#39;s disease, and other autoimmune diseases. 
     Kits 
     The present invention also provides kits for the administration of any CD8 binding agent described herein (e.g. with or without additional therapeutic agents). The kit is an assemblage of materials or components, including at least one of the inventive pharmaceutical compositions described herein. Thus, in some embodiments, the kit contains at least one of the pharmaceutical compositions described herein. 
     The exact nature of the components configured in the kit depends on its intended purpose. In one embodiment, the kit is configured for the purpose of treating human subjects. 
     Instructions for use may be included in the kit. Instructions for use typically include a tangible expression describing the technique to be employed in using the components of the kit to effect a desired therapeutic outcome, such as to treat cancer. Optionally, the kit also contains other useful components, such as, diluents, buffers, pharmaceutically acceptable carriers, syringes, catheters, applicators, pipetting or measuring tools, bandaging materials or other useful paraphernalia as will be readily recognized by those of skill in the art. 
     The materials and components assembled in the kit can be provided to the practitioner stored in any convenience and suitable ways that preserve their operability and utility. For example, the components can be provided at room, refrigerated or frozen temperatures. The components are typically contained in suitable packaging materials. In various embodiments, the packaging material is constructed by well-known methods, preferably to provide a sterile, contaminant-free environment. The packaging material may have an external label which indicates the contents and/or purpose of the kit and/or its components. 
     Definitions 
     As used herein, “a,” “an,” or “the” can mean one or more than one. 
     Further, the term “about” when used in connection with a referenced numeric indication means the referenced numeric indication plus or minus up to 10% of that referenced numeric indication. For example, the language “about 50” covers the range of 45 to 55. 
     An “effective amount,” when used in connection with medical uses is an amount that is effective for providing a measurable treatment, prevention, or reduction in the rate of pathogenesis of a disease of interest. 
     As used herein, something is “decreased” if a read-out of activity and/or effect is reduced by a significant amount, such as by at least about 10%, at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, at least about 95%, at least about 97%, at least about 98%, or more, up to and including at least about 100%, in the presence of an agent or stimulus relative to the absence of such modulation. As will be understood by one of ordinary skill in the art, in some embodiments, activity is decreased and some downstream read-outs will decrease but others can increase. 
     Conversely, activity is “increased” if a read-out of activity and/or effect is increased by a significant amount, for example by at least about 10%, at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, at least about 95%, at least about 97%, at least about 98%, or more, up to and including at least about 100% or more, at least about 2-fold, at least about 3-fold, at least about 4-fold, at least about 5-fold, at least about 6-fold, at least about 7-fold, at least about 8-fold, at least about 9-fold, at least about 10-fold, at least about 50-fold, at least about 100-fold, in the presence of an agent or stimulus, relative to the absence of such agent or stimulus. 
     As referred to herein, all compositional percentages are by weight of the total composition, unless otherwise specified. As used herein, the word “include,” and its variants, is intended to be non-limiting, such that recitation of items in a list is not to the exclusion of other like items that may also be useful in the compositions and methods of this technology. Similarly, the terms “can” and “may” and their variants are intended to be non-limiting, such that recitation that an embodiment can or may comprise certain elements or features does not exclude other embodiments of the present technology that do not contain those elements or features. 
     Although the open-ended term “comprising,” as a synonym of terms such as including, containing, or having, is used herein to describe and claim the invention, the present invention, or embodiments thereof, may alternatively be described using alternative terms such as “consisting of” or “consisting essentially of.” 
     As used herein, the words “preferred” and “preferably” refer to embodiments of the technology that afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the technology. 
     The amount of compositions described herein needed for achieving a therapeutic effect may be determined empirically in accordance with conventional procedures for the particular purpose. Generally, for administering therapeutic agents for therapeutic purposes, the therapeutic agents are given at a pharmacologically effective dose. A “pharmacologically effective amount,” “pharmacologically effective dose,” “therapeutically effective amount,” or “effective amount” refers to an amount sufficient to produce the desired physiological effect or amount capable of achieving the desired result, particularly for treating the disorder or disease. An effective amount as used herein would include an amount sufficient to, for example, delay the development of a symptom of the disorder or disease, alter the course of a symptom of the disorder or disease (e.g., slow the progression of a symptom of the disease), reduce or eliminate one or more symptoms or manifestations of the disorder or disease, and reverse a symptom of a disorder or disease. Therapeutic benefit also includes halting or slowing the progression of the underlying disease or disorder, regardless of whether improvement is realized. 
     Effective amounts, toxicity, and therapeutic efficacy can be determined by standard pharmaceutical procedures in cell cultures or experimental animals, e.g., for determining the LD50 (the dose lethal to about 50% of the population) and the ED50 (the dose therapeutically effective in about 50% of the population). The dosage can vary depending upon the dosage form employed and the route of administration utilized. The dose ratio between toxic and therapeutic effects is the therapeutic index and can be expressed as the ratio LD50/ED50. In some embodiments, compositions and methods that exhibit large therapeutic indices are preferred. A therapeutically effective dose can be estimated initially from in vitro assays, including, for example, cell culture assays. Also, a dose can be formulated in animal models to achieve a circulating plasma concentration range that includes the IC50 as determined in cell culture, or in an appropriate animal model. Levels of the described compositions in plasma can be measured, for example, by high performance liquid chromatography. The effects of any particular dosage can be monitored by a suitable bioassay. The dosage can be determined by a physician and adjusted, as necessary, to suit observed effects of the treatment. 
     In certain embodiments, the effect will result in a quantifiable change of at least about 10%, at least about 20%, at least about 30%, at least about 50%, at least about 70%, or at least about 90%. In some embodiments, the effect will result in a quantifiable change of about 10%, about 20%, about 30%, about 50%, about 70%, or even about 90% or more. Therapeutic benefit also includes halting or slowing the progression of the underlying disease or disorder, regardless of whether improvement is realized. 
     As used herein, “methods of treatment” are equally applicable to use of a composition for treating the diseases or disorders described herein and/or compositions for use and/or uses in the manufacture of a medicaments for treating the diseases or disorders described herein. 
     EXAMPLES 
     Example 1. Construction and Evaluation of VHHs Specific for Human CD8 
     Isolation of Antigen-Specific VHHs 
     A VHH library was constructed from an immunized llama. Three consecutive rounds of panning of a VHH library were performed in solution using stably transfected CHO-K1 cells expressing human CD8. The enrichment for antigen-specific phages was assessed after each round of panning by comparing the number of phagemid particles eluted from transfected cells (output) with the number of phagemid particles used for panning (input). The phage output increased about 10 2 -fold in the 2 nd  round and about 10 3 -fold in the 3 rd  round, as compared to the output from the 1 st  round. The input phage was always about 10 11  and the output from first round was about 10 7  phage particles. 285 randomly selected colonies from the 1 st , 2 nd  and 3 rd  panning rounds (95 from each round) were sequenced and then grouped based on CDR3 sequences. Using crude periplasmic extracts including VHHs, 89 unique sequences were analyzed by flow cytometry for specificity to human CD8 using CHO-K1 cells stably transfected with human CD8. The parental non-transfected CHO-K1 cells served as negative control cell. An irrelevant VHH was used as negative Nanobody control. Flow cytometry experiments revealed that 69 different VHHs, belonging to 31 different groups (see  FIG.  3   ), were specific for human CD8. The table below provides a description of 69 clones representing the 69 different anti-human CD8 VHH genes.  E. coli  TG1 harboring recombinant phagemid pMECS containing anti-human CD8A VHH sequences was generated and stored at −80° C. The vector pMECS codes for ampicillin resistance. 
     
       
         
           
               
               
               
               
             
               
                   
                   
               
               
                   
                   E. coli  strain + Vector 
                 VHH (Nb) 
                 NSF Glycerol Stock No. 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 TG1, pMECS 
                 1CDA 7 
                 4757 
               
               
                   
                 TG1, pMECS 
                 1CDA 12 
                 4758 
               
               
                   
                 TG1, pMECS 
                 1CDA 14 
                 4759 
               
               
                   
                 TG1, pMECS 
                 1CDA 15 
                 4760 
               
               
                   
                 TG1, pMECS 
                 1CDA 17 
                 4761 
               
               
                   
                 TG1, pMECS 
                 1CDA 18 
                 4762 
               
               
                   
                 TG1, pMECS 
                 1CDA 19 
                 4763 
               
               
                   
                 TG1, pMECS 
                 1CDA 24 
                 4764 
               
               
                   
                 TG1, pMECS 
                 1CDA 26 
                 4765 
               
               
                   
                 TG1, pMECS 
                 1CDA 28 
                 4766 
               
               
                   
                 TG1, pMECS 
                 1CDA 37 
                 4767 
               
               
                   
                 TG1, pMECS 
                 1CDA 43 
                 4768 
               
               
                   
                 TG1, pMECS 
                 1CDA 45 
                 4769 
               
               
                   
                 TG1, pMECS 
                 1CDA 47 
                 4770 
               
               
                   
                 TG1, pMECS 
                 1CDA 48 
                 4771 
               
               
                   
                 TG1, pMECS 
                 1CDA 58 
                 4772 
               
               
                   
                 TG1, pMECS 
                 1CDA 65 
                 4773 
               
               
                   
                 TG1, pMECS 
                 1CDA 68 
                 4774 
               
               
                   
                 TG1, pMECS 
                 1CDA 73 
                 4775 
               
               
                   
                 TG1, pMECS 
                 1CDA 75 
                 4776 
               
               
                   
                 TG1, pMECS 
                 1CDA 86 
                 4777 
               
               
                   
                 TG1, pMECS 
                 1CDA 87 
                 4778 
               
               
                   
                 TG1, pMECS 
                 1CDA 88 
                 4779 
               
               
                   
                 TG1, pMECS 
                 1CDA 89 
                 4780 
               
               
                   
                 TG1, pMECS 
                 1CDA 92 
                 4781 
               
               
                   
                 TG1, pMECS 
                 1CDA 93 
                 4782 
               
               
                   
                 TG1, pMECS 
                 2CDA 1 
                 4783 
               
               
                   
                 TG1, pMECS 
                 2CDA 5 
                 4784 
               
               
                   
                 TG1, pMECS 
                 2CDA 22 
                 4785 
               
               
                   
                 TG1, pMECS 
                 2CDA 28 
                 4786 
               
               
                   
                 TG1, pMECS 
                 2CDA 62 
                 4787 
               
               
                   
                 TG1, pMECS 
                 2CDA 68 
                 4788 
               
               
                   
                 TG1, pMECS 
                 2CDA 73 
                 4789 
               
               
                   
                 TG1, pMECS 
                 2CDA 74 
                 4790 
               
               
                   
                 TG1, pMECS 
                 2CDA 75 
                 4791 
               
               
                   
                 TG1, pMECS 
                 2CDA 77 
                 4792 
               
               
                   
                 TG1, pMECS 
                 2CDA 81 
                 4793 
               
               
                   
                 TG1, pMECS 
                 2CDA 87 
                 4794 
               
               
                   
                 TG1, pMECS 
                 2CDA 88 
                 4795 
               
               
                   
                 TG1, pMECS 
                 2CDA 89 
                 4796 
               
               
                   
                 TG1, pMECS 
                 2CDA 91 
                 4797 
               
               
                   
                 TG1, pMECS 
                 2CDA 92 
                 4798 
               
               
                   
                 TG1, pMECS 
                 2CDA 93 
                 4799 
               
               
                   
                 TG1, pMECS 
                 2CDA 94 
                 4800 
               
               
                   
                 TG1, pMECS 
                 2CDA 95 
                 4801 
               
               
                   
                 TG1, pMECS 
                 3CDA 3 
                 4802 
               
               
                   
                 TG1, pMECS 
                 3CDA 8 
                 4803 
               
               
                   
                 TG1, pMECS 
                 3CDA 11 
                 4804 
               
               
                   
                 TG1, pMECS 
                 3CDA 18 
                 4805 
               
               
                   
                 TG1, pMECS 
                 3CDA 19 
                 4806 
               
               
                   
                 TG1, pMECS 
                 3CDA 21 
                 4807 
               
               
                   
                 TG1, pMECS 
                 3CDA 24 
                 4808 
               
               
                   
                 TG1, pMECS 
                 3CDA 28 
                 4809 
               
               
                   
                 TG1, pMECS 
                 3CDA 29 
                 4810 
               
               
                   
                 TG1, pMECS 
                 3CDA 31 
                 4811 
               
               
                   
                 TG1, pMECS 
                 3CDA 32 
                 4812 
               
               
                   
                 TG1, pMECS 
                 3CDA 33 
                 4813 
               
               
                   
                 TG1, pMECS 
                 3CDA 37 
                 4814 
               
               
                   
                 TG1, pMECS 
                 3CDA 40 
                 4815 
               
               
                   
                 TG1, pMECS 
                 3CDA 41 
                 4816 
               
               
                   
                 TG1, pMECS 
                 3CDA 48 
                 4817 
               
               
                   
                 TG1, pMECS 
                 3CDA 57 
                 4818 
               
               
                   
                 TG1, pMECS 
                 3CDA 65 
                 4819 
               
               
                   
                 TG1, pMECS 
                 3CDA 70 
                 4820 
               
               
                   
                 TG1, pMECS 
                 3CDA 73 
                 4821 
               
               
                   
                 TG1, pMECS 
                 3CDA 83 
                 4822 
               
               
                   
                 TG1, pMECS 
                 3CDA 86 
                 4823 
               
               
                   
                 TG1, pMECS 
                 3CDA 88 
                 4824 
               
               
                   
                 TG1, pMECS 
                 3CDA 90 
                 4825 
               
               
                   
                   
               
            
           
         
       
     
     Transformation of Non-Suppressor Strain (e.g. WK6) with Recombinant pMECS 
     The VHH gene cloned in pMECS vector contained PelB signal sequence at the N-terminus and HA tag and His 6  tag at the C-terminus (PelB leader-VHH-HA-His 6 ). The PelB leader sequence directed the VHH to the periplasmic space of the  E. coli , and the HA and His 6  tags was used for the purification and detection of VHH (e.g. in ELISA, Western Blot, etc.). 
     In pMECS vector, the His 6  tag was followed by an amber stop codon (TAG) and this amber stop codon was followed by gene III of M13 phage. In suppressor  E. coli  strains (e.g. TG1), the amber stop codon was read as glutamine and therefore the VHH was expressed as fusion protein with protein Ill of the phage which allowed the display of the VHH on the phage coat for panning. In TG1 supressor strains, the efficiency of suppression is not 100% and therefore the expression of VHHs in suppressor strains led to two different types of VHH molecules, fused to protein Ill and without protein Ill). In non-suppressor  E. coli  strains (e. g., WK6), the amber stop codon was read as stop codon and therefore the resulting VHH was not fused to protein Ill. 
     In order to express and purify VHHs cloned in pMECS vector, pMECS was prepared containing the gene of the VHH of interest, and the plasmid was transformed into a non-suppressor strain (e.g., WK6). The VHH of the resulting clone was sequenced using the MP057 primer (5′-TTATGCTTCCGGCTCGTATG-3′) (SEQ ID NO:1033) to verify the identity of the clone. Antigen binding capacity was retested by ELISA or any other appropriate assay. 
     The non-suppressor strain (e.g., WK6) containing the recombinant pMECS vector with the VHH gene was used for the expression and purification of the VHH. 
     In pMECS vector, the His 6  tag was cleaved off upon storage of the VHH. Accordingly, the VHH gene was recloned from pMECS into pHEN6c vector, if the His 6  tag was to be used for detection, etc. Specifically, the VHH gene was amplified by PCR using recombinant pMECS harboring the VHH gene as template and primers A6E and PMCF. 
     Primers A6E and PMCF were framework1 and framework4 primers, respectively. The primer sequences were as follows: 
     
       
         
           
               
            
               
                 Primer A6E 
               
               
                 (SEQ ID NO:  1034) 
               
               
                 (5’ GAT GTG CAG CTG CAG GAG TCT GGR* GGA GG 3’). 
               
               
                   
               
               
                 Primer PMCF 
               
               
                 (SEQ ID NO:  1035) 
               
               
                 (5’ CTA GTG CGG CCG CTG AGG AGA CGG TGA CCT GGG 
               
               
                   
               
               
                 T 3’). 
               
               
                   
               
               
                 Universal reverse primer 
               
               
                 (SEQ ID NO: 1036) 
               
               
                 (5’ TCA CAC AGG AAA CAG CTA TGA C 3’). 
               
               
                   
               
               
                 Universal forward primer 
               
               
                 (SEQ ID NO: 1037) 
               
               
                 (5’ CGC CAG GGT TTT CCC AGT CAC GAC 3’). 
               
            
           
         
       
         
         
           
             *R stands for A or G. PstI, NotI and BstEII (Eco91I) recognition sequences are shown in bold, italic and underline, respectively. 
           
         
       
    
     The amplification protocol included about 30 cycles of PCR, each cycle included 30 seconds at 94° C., 30 seconds at 55° C. and 45 seconds at 72° C., followed by 10 minutes extension at 72° C. at the end of PCR. A fragment of about 400 bp was amplified. 
     The PCR product was purified (e.g. by Qiaquick PCR purification kit from Qiagen) and digested overnight with PstI. The purified PCR product was digested with BstEII overnight (or with Eco91I from Fermentas). The temperature used for digestion varied. For example, digestion with BstEII was done at 50° C. or 60° C. depending on the supplier of the enzyme. 
     For ligation, the PCR product was purified. The pHEN6c vector was digested with PstI for 3 hours, purified as described above, and then digested with BstEII for 2 to 3 hours. Alternatively, digestion was carried out using Eco91I from Fermentas. The digested vector was ran on 1% agarose gel, with the vector band excised out of the gel and purified (e.g. by Qiaquick gel extraction kit from Qiagen). The PCR fragment was subsequently ligated to the vector. 
     Electrocompetent WK6 cells were transformed with the ligation reaction, and transformants were selected using LB/agar/ampicillin (100 μg/ml)/glucose (1-2%) plates. Positive clones were screened by PCR using universal reverse and universal forward primers. A fragment of about 550 bp was amplified, if the insert was present. To verify the identity of the clones, at least 2 clones per each VHH were sequenced using universal reverse primers. Antigen binding capacity was retested by ELISA or any other appropriate assay. 
     Following the above protocol, the VHH gene cloned in pHEN6c vector was generated which contained PelB signal sequence at the N-terminus and Hiss-tail at the C-terminus. The PelB leader sequence directed the VHH to the periplasmic space of the  E. coli , and the His-tag was used for the purification and detection of VHH (e.g. in ELISA, Western Blot, etc.). 
     Expression and Purification of VHHs 
     Expression and purification of VHHs were carried out. Specifically, on day 1, 10-20 ml of LB+ampicillin (100 μg/ml)+glucose (1%) were innoculated with a freshly transformed WK6 colony. This pre-culture was incubated at 37° C. overnight with shaking at 200-250 rpm. On day 2, a TB medium was used for expressing the VHHs. The TB medium included, per liter: 2.3 g KH 2 PO 4 , 16.4 g K 2 HPO 4 .3H 2 O, 12 g Tryptone (Duchefa Biochemie), 24 g Yeast (Duchefa Biochemie), and 4 ml 100% glycerol (Duchefa Biochemie) 
     A baffled shaker flask of 1 liter was filled with 330 ml TB and autoclaved. KH 2 PO 4  and K 2 HPO 4 .3H 2 O were not autoclaved. Instead, KH 2 PO 4  and K 2 HPO 4 .3H 2 O were prepared, filter sterilized, and then added to the rest of the medium that was already autoclaved. About 1 ml of the pre-culture was added to 330 ml of TB supplemented with 100 μg/ml Ampicillin, 2 mM MgCl 2  and 0.1% glucose and subsequently grew at 37° C. with shaking (200-250 rpm) until an OD 600  of 0.6-0.9 was reached. IPTG (final concentration of 1 mM) was added to induce VHH expression. The culture was incubated at 28° C. with shaking overnight (about 16-18 hours). The OD 600  after overnight induction was usually between 25 and 30. At least 1 liter of culture (3 bottles) per clone was prepared with an average yield of between 1 and 15 mg/I. 
     Extraction of the VHHs from the periplasm of  E. coli  was carried out on day 3. The solutions used included: TES: 0.2 M Tris pH 8.0, 0.5 mM EDTA, 0.5 M sucrose, TES/4: TES diluted 4 times in water. 
     The overnight induced cultures were centrifuged for 8 minutes at 8000 rpm. The cell pellets from 1 liter culture were resuspended in 12 ml TES by pipetting up and down and shaken for 1 hour on ice. Per each 12 ml TES used, about 18 ml TES/4 were added and incubated on ice for an additional hour with shaking followed by centrifuge for 30 minutes at 8000 rpm at 4° C. The supernatant which contained proteins extracted from the periplasmic spaced was transferred to fresh falcon tubes. 
     The VHHs were subsequently purified by IMAC which utilized the following solution: HIS-select (SIGMA), PBS, and 50 mM NaAcetate pH 4.6. 
     His-select was equilibrated with PBS. Specifically, per periplasmic extract derived from 1 liter culture, 1 ml of Resin (about 2 ml His-select solution) was added to a 50 ml falcon tube. PBS was also added to final volume of 50 ml and mixed. Centrifugation was carried out at 2000 rpm for 2 minutes, and the supernatant was discarded. The resin was washed with PBS twice as described above. The periplasmic extract was added to the resin, incubated for 30 minutes to 1 hour at room temperature with gentle shaking. The samples were loaded on PD-10 columns with a filter at the bottom (GE healthcare, cat. No. 17-0435-01) and washed with 50 to 100 ml PBS (50-100 ml PBS per 1 ml resin used). Elution was carried out for 3 times, each time with 1 ml PBS/0.5 M imidazole per 1 ml resin used (for efficient elution, resuspend the beads and leave overnight at 4° C. with the bottom of the column closed). Dialysis was performed overnight at 4° C. against PBS (cutoff 3500 daltons) to remove imidazole. For efficient dialysis, the dialysis buffer (PBS) was changed 2-3 times. Alternatively, instead of elution with imidazole, the bound VHHs could be eluted with 10 ml 50 mM Na-acetate pH 4.6. If 50 mM Na-acetate pH 4.6 was used to elute VHHs, the eluted VHHs was immediately neutralized with 1M Tris pH 8.0, and no dialysis was required. 
     The amount of protein was estimated by OD 280  measurement of eluted sample. Extinction coefficient of each clone was determined by protParam tool under primary structure analysis at the Expasy proteomics server. Further purification of VHHs could be achieved by different methods. For example, the samples could be concentrated (Vivaspin 5000 MW cutoff, Vivascience) by centrifuging at 2000 rpm at 4° C. until an appropriate volume for loading on a Superdex 75 16/60 was obtained (max. 4 ml). The concentrated sample was loaded on a Superdex 75 16/60 column equilibrated with PBS. Peak fractions were pooled, and OD 280  measurements were performed for quantification. In general, VHHs eluted after 85-95 minutes when run at 1 ml/min. Aliquots of concentrated VHH samples were stored at −20° C. at a concentration of about 1 mg/ml. 
     Example 2. Functional Characterization of Human CD8 Binding VHHs 
     The binding characteristics of various VHHs (as described in Example 1) were tested by flow cytometry. HEK293-T cells were transfected with a human CD8α expression plasmid and stained with the His-tagged VHHs at 2 μg/ml, followed by staining with an anti-His Fitc conjugated antibody. Binding was measured by detecting cellular fluorescence via flow cytometry. Results as shown in  FIG.  4    show that the VHHs bound to CD8. 
     Example 3. pSTAT Signaling Induced by Anti-Human CD8 VHH Chimeras 
     The term “AcTaferon” (AFN) is used herein to reference an interferon-based chimera. In the following example, unless noted, mutations to IFN are relative to human IFN-α2 (SEQ ID NO:12). 
     A pSTAT signaling assay was undertaken in CD8 positive and CD8 negative cells. Chimeras studied were anti-human CD8 VHH/ /human IFN R149A fusions. 
     Based on FACS analysis of binding to CD8 and on sequence similarities, six CD8 VHH&#39;s were selected for further analysis: 3CDA19, 3CDA65, 3CDA33, 3CDA28, 3CDA31, and 2CDA5. These VHH&#39;s were cloned into an AcTaferon (AFN) context in the pMTW vector for eukaryotic expression as follows: pmTW-SlgK-hCD8_VHH-(GGS) 20 -hlFNa2_R149A-GGS-(His) 9 . Resulting proteins were produced in Hek293F cells with 25K PEI (polyethylenimine) according to standard protocols. Medium was harvested, cells removed by centrifugation and filter-sterilized. Recombinant proteins were purified using Ni Excel resin (GE Healthcare) according to the manufacturer&#39;s instructions and imidazole removed from the samples with PD10 columns (GE Healthcare). 
     PBMCs from buffy coats of healthy donors were isolated using density gradient centrifugation with Ficoll-Paque (GE Healthcare). Cells were washed twice with FACS buffer (2% FBS, 1 mM EDTA in PBS) and stained with anti-human CD8 APC (clone REA734; Miltenyi Biotec) for 20 minutes at 4° C. After two washes, cells were stimulated with a serial dilution CD8-AcTaferons for 15 minutes at 37° C. After fixation (10 minutes, 37° C., Fix Buffer I; BD Biosciences) and permeabilization (30 minutes, on ice, Perm III Buffer I; BD Biosciences) and washing, cells were stained with anti-STAT1 pY701 Ab (BD Biosciences). Samples were acquired with a FACSCalibur (BD Biosciences), with the CellQuest Pro Version 4.0.2 software (BD Biosciences). 
     As shown in  FIGS.  5 A-B , CD8 VHH targeted mutant IFN (i.e., R149A) was able to phosphorylate STAT1 in CD8 positive ( FIG.  5 A ) but not CD8 negative cells ( FIG.  5 B ) indicating efficient CD8 targeting. 
     Example 4. pSTAT1 Signaling Induced by Additional Anti-Human CD8 VHH AcTaferons 
     In Example 3, CD8 VHHs were selected from the larger sequence groups 1, 2, and 15 as defined in  FIG.  3   . Based on binding to CD8 in FACS (see Example 2 and  FIG.  4   ) additional sequence groups, including group 3, 4, 22, and 30, showed strong binding to CD8. These CD8 VHHs were selected for further evaluation of their efficiency of human CD8 targeting of AcTaferons by quantification of STAT1 phosphorylation in CD8-positive and CD8-negative peripheral blood mononuclear cells (PBMCs) in FACS. Sequence groups 3 and 4 were considered similar and the stronger binding VHH 2CDA74 was selected as representative member. The sequence of 2CDA74 contains a free cysteine in CDR2 at position 50. This residue was mutated to serine to avoid disulfide-based dimer formation. The mutation resulted in 2CDA74 having a CDR2 sequence of SSISRSDGSTY (SEQ ID NO: 1221). 
     The affinities of CD8 VHH&#39;s 1CDA65, 2CDA5, 2CDA68, 2CDA74 (C50S), and 3CDA19 (sequences provided below) were measured (see Table 1). Affinities of the CD8 VHH&#39;s were measured using bio-layer interferometry an Octet RED96 system (FortéBio): biotinylated CD8 (Sino Biological) was immobilized on streptavidin biosensors (FortéBio) and dipped in a serial dilution CD8 AFN&#39;s. Affinities were calculated with the Octet software (FortéBio). 
     
       
         
           
               
            
               
                 1CDA65 
               
               
                 (SEQ ID NO: 1217) 
               
               
                 QVQLQESGGGLVQPGGSLRLSCAASGSIFSINVMGWYRQTPGKERELVAK 
               
               
                   
               
               
                 ITNFGITSYADSAQGRFTISRGNAKNTVYLQMNSLKPEDTAVYYCNLDTT 
               
               
                   
               
               
                 GWGPPPYQYWGQGTQVTVSS. 
               
               
                   
               
               
                 2CDA5 
               
               
                 (SEQ ID NO: 1218) 
               
               
                 QVQLQESGGGLVQAGDSLRLTCTASGRTFSNYGIGWFRQAPGKEREFVAG 
               
               
                   
               
               
                 INWSGESADYADSVKGRFTISRDNAKNTVYLQMNSLKPEDTAVYYCAAGE 
               
               
                   
               
               
                 SGVWVGGLDYWXQGTQVTVSS. 
               
               
                   
               
               
                 2CDA68 
               
               
                 (SEQ ID NO: 1219) 
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGRTFSSYVMGWFRQAPGKEREFVAQ 
               
               
                   
               
               
                 ISWSAGSIYYADSVKGRFTISNDNAKRTVYLQMNSLKPEDTAVYYCAERG 
               
               
                   
               
               
                 YAYCSDDGCQRTQDYDYWGQGTQVTVSS. 
               
               
                   
               
               
                 2CDA74(C50S) 
               
               
                 (SEQ ID NO: 1216) 
               
               
                 QVQLQESGGGLVQAGGSLRLSCAVSGFTFDNYAIGWFRQAPGKEREGVSS 
               
               
                   
               
               
                 ISRSDGSTYYADSVRGRFTISSDNAKNTVYLQMNSLKPEDTAVYYCAAET 
               
               
                   
               
               
                 SADSGEFRFGWVLKPSLYDYWGQGTQVTVSS. 
               
               
                   
               
               
                 3CDA19 
               
               
                 (SEQ ID NO: 1220) 
               
               
                 QVQLQESGGGLVQAGGSLRLSCAASGFSSDDYTIGWFRQAPGKEREGISC 
               
               
                   
               
               
                 FSSSDGSTGFADSVKGRFTISSDNATNTVYLEMNSLKPEDTAVYYCAADF 
               
               
                   
               
               
                 NVWSPPICGSRWYGPPPGGMEYWGKGTQVTVSS. 
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 KD (M) 
                 KD Error 
                 kon(1/Ms) 
                 kon Error 
                 kdis (1/s) 
                 kdis Error 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 2CDA5 
                 2.01E−08 
                 3.41E−10 
                 1.02E+05 
                 1.43E+03 
                 2.04E−03 
                 1.95E−05 
               
               
                 3CDA19 
                 2.60E−09 
                 3.29E−11 
                 2.07E+05 
                 1.10E+03 
                 5.37E−04 
                 6.17E−06 
               
               
                 1CDA65 
                 3.09E−09 
                 1.87E−11 
                 3.13E+05 
                 1.18E+03 
                 9.65E−04 
                 4.59E−06 
               
               
                 2CDA74 (C50S) 
                 1.94E−08 
                 9.55E−10 
                 4.97E+03 
                 5.44E+01 
                 9.67E−05 
                 4.63E−06 
               
               
                 2CDA68 
                 9.30E−09 
                  1.32−10 
                 3.24E+05 
                 4.10E+03 
                 3.01E−03 
                 1.93E−05 
               
               
                   
               
            
           
         
       
     
     The CD8 VHH&#39;s 1CDA65, 2CDA5, 2CDA68, 2CDA74 (C50S), and 3CDA19 were cloned into an AFN in the pMTW vector for eukaryotic expression as follows: pmTW-SlgK-hCD8_VHH-(GGS) 20 -hlFNa2_R149A-GGS-(His) 9 . Resulting CD8 VHH AFN proteins (i.e., AFN 1CDA65, AFN 2CDA5, AFN 2CDA68, AFN 2CDA74 (C50S), and AFN 3CDA19) were produced in ExpiCHO cells (Thermo Fisher) according to the manufacturers guidelines. Medium was harvested, cells removed by centrifugation and filter-sterilized. Recombinant proteins were purified using HisPur Cobalt beads (Thermo Fisher) and imidazole removed from the samples with PD10 columns (GE Healthcare). 
     To test the biological activity of the resulting CD8 VHH AFN&#39;s, PBMCs were isolated from buffy coats of healthy donors using density gradient centrifugation with Ficoll-Paque (GE Healthcare). Cells were washed twice with FACS buffer (2% FBS, 1 mM EDTA in PBS) and stained with anti-human CD8-FITC (clone REA734; Miltenyi Biotec) for 20 minutes at 4° C. After two washes, cells were stimulated with serial dilutions of a CD8 VHH AFN (i.e., AFN 1CDA65, AFN 2CDA5, AFN 2CDA68, AFN 2CDA74 (C50S), or AFN 3CDA19) or wild type IFNα2 (positive control) for 15 minutes at 37° C. After fixation (10 minutes, 37° C., Fix Buffer I; BD Biosciences) and permeabilization (30 minutes, on ice, Perm III Buffer I; BD Biosciences) and washing, cells were stained with anti-STAT1 pY701 Ab (BD Biosciences). Samples were acquired with a FACS Calibur (BD Biosciences), with the CellQuest Pro Version 4.0.2 software (BD Biosciences) and analyzed using the FlowJo software (FlowJo). 
       FIGS.  6 A-F  show that treatment with CD8 VHH AFNs lead to greater phosphorylation of STAT1 in CD8 positive cells as compared to CD8 negative cells (data plotted as increase over baseline STAT1 phosphorylation). 
     Example 5. Cross-Reactivity with Cynomolgus CD8 
     The ability of the CD8 VHH&#39;s from Example 4 to bind to human and cynomolgus CD8 alpha in FACS was tested. 
     Hek293T cells were transiently transfected with expression plasmids encoding human or cynomolgus CD8 alpha using standard calcium phosphate transfection. Two days later, cells were resuspended and sequentially incubated with serial dilutions CD8 AFN&#39;s and FITC coupled THE HIS Ab (Genscript). Samples were acquired with a FACS Calibur (BD Biosciences), with the CellQuest Pro Version 4.0.2 software (BD Biosciences) and analyzed using the FlowJo software (FlowJo). 
       FIGS.  7 A-E  show that all five CD8 VHHs bind equally as well to human and cynomolgus CD8 alpha. 
     EQUIVALENTS 
     While the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modifications and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth and as follows in the scope of the appended claims. 
     Those skilled in the art will recognize, or be able to ascertain, using no more than routine experimentation, numerous equivalents to the specific embodiments described specifically herein. Such equivalents are intended to be encompassed in the scope of the following claims. 
     INCORPORATION BY REFERENCE 
     All patents and publications referenced herein are hereby incorporated by reference in their entireties. 
     The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. 
     As used herein, all headings are simply for organization and are not intended to limit the disclosure in any manner. 
     The content of any individual section may be equally applicable to all sections. 
     REFERENCES 
     The following are hereby incorporated by reference in their entireties.
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