TREATMENT OF AUTOIMMUNE DISEASES WITH ANTAGONISTS WHICH BIND TO B CELL SURFACE MARKERS

Abstract: The present invention concerns treatment of autoimmune diseases with antagonists which bind to B cell surface markers, such as CD19 or CD20.

Description: TREATMENT OF AUTOIMMUNE DISEASES WITH ANTAGONI STS WHICH BIND TO B CELL SURFACE ^ Fie ,ld-, o .f th L e τ Inventi •on MARKERS The present invention concerns treatment of autoimmune diseases with antagonists which bind to B cell surface markers, such as CD19 or CD20. Background of the Invention Lymphocytes are one of many types of white blood cells produced in the bone marrow during the process of hematopoiesis. There are two major populations of lymphocytes: B lymphocytes (B cells) and T lymphocytes (T cells). The lymphocytes of particular interest herein are B cells. B cells mature within the bone marrow and leave the marrow expressing an antigen-binding antibody on their cell surface. When a naive B cell first encounters the antigen for which its membrane-bound antibody is specific, the cell begins to divide rapidly and its progeny differentiate into memory B cells and effector cells called "plasma cells". Memory B cells have a longer life span and continue to express membrane-bound antibody with the same specificity as the original parent cell. Plasma cells do not produce membrane-bound antibody but instead produce the antibody in a form that can be secreted. Secreted antibodies are the major effector molecule of humoral immunity. The CD20 antigen (also called human B-lymphocyte-restricted differentiation antigen, Bp35) is a hydrophobic transmembrane protein with a molecular weight of approximately 35 kD located on pre-B and mature B lymphocytes (Valentine etal. J. Biol Chem. 264(19): 11282- 11287 (1989); and Einfeld et al. EMBOJ. 7(3):711- 717 (1988)). The antigen is also expressed on greater than 90% of B cell non-Hodgkin's lymphomas (NHL) (Anderson et al. Blood 63(6): 1424-1433 (1984)), but is not found on hematopoietic stem cells, pro-B cells, normal plasma cells or other normal tissues (Tedder et al. J. Immunol. 135(2):973-979 (1985)). CD20 regulates an early step(s) in the activation process for cell cycle initiation and differentiation (Tedder et al, supra) and possibly functions as a calcium ion channel (Tedder et al. J. Cell. Biochem. 14D:195 (1990)). Given the expression of CD20 in B cell lymphomas, this antigen can serve as a candidate for "targeting" of such lymphomas. In essence, such targeting can be generalized as follows: antibodies specific to the CD20 surface antigen of B cells are administered to a patient. These anti-CD20 antibodies specifically bind to the CD20 antigen of (ostensibly) both normal and malignant B cells; the antibody bound to the CD20 surface antigen may lead to the destruction and depletion of neoplastic B cells. Additionally, chemical agents or radioactive labels having the potential to destroy the tumor can be conjugated to the anti-CD20 antibody such that the agent is specifically "delivered" to the neoplastic B cells. Irrespective of the approach, a primary goal is to destroy the tumor; the specific approach can be determined by the particular anti-CD20 antibody which is utilized and, thus, the available approaches to targeting the CD20 antigen can vary considerably. CD 19 is another antigen that is expressed on the surface of cells of the B lineage. Like CD20, CD 19 is found on cells throughout differentiation of the lineage from the stem cell stage up to a point just prior to terminal differentiation into plasma cells (Nadler, L. Lymphocyte Typing II 2: 3-37 and Appendix, Renling et al. eds. (1986) by Springer Verlag). Unlike CD20 however, antibody binding to CD 19 causes internalization of the CD 19 antigen. CD19 antigen is identified by the HD237-CD19 antibody (also called the "B4" antibody) (Kiesel et al. Leukemia Research 77, 12: 1119 (1987)), among others. The CD 19 antigen is present on 4-8% of peripheral blood mononuclear cells and on greater than 90% of B cells isolated from peripheral blood, spleen, lymph node or tonsil. CD 19 is not detected on peripheral blood T cells, monocytes or granulocytes. Virtually all non-T cell acute lymphoblastic leukemias (ALL), B cell chronic lymphocytic leukemias (CLL) and B cell lymphomas express CD 19 detectable by the antibody B4 (Nadler et al. J. Immunol. 131:244 (1983); and Nadler et al. in Progress in Hematology Vol. XII pp. 187-206. Brown, E. ed. (1981) by Grune & Stratton, Inc). Additional antibodies which recognize differentiation stage-specific antigens expressed by cells of the B cell lineage have been identified. Among these are the B2 antibody directed against the CD21 antigen; B3 antibody directed against the CD22 antigen; and the J5 antibody directed against the CD 10 antigen (also called CALLA). See US Patent No. 5,595,721 issued January 21, 1997 (Kaminski et al). The rituximab (RITUXAN®) antibody is a genetically engineered chimeric murine/human monoclonal antibody directed against the CD20 antigen. Rituximab is the antibody called "C2B8" in US Patent No. 5,736,137 issued April 7, 1998 (Anderson et al.). RITUXAN® is indicated for the treatment of patients with relapsed or refractory low-grade or follicular, CD20 positive, B cell non-Hodgkin's lymphoma. In vitro mechanism of action studies have demonstrated that RITUXAN® binds human complement and lyses lymphoid B cell lines through complement-dependent cytotoxicity (CDC) (Reff etal.5/oo<i83(2):435-445 (1994)). Additionally, ithas significant activity in assays for antibody-dependent cellular cytotoxicity (ADCC). More recently, RITUXAN® has been shown to have anti-proliferative effects in tritiated thymidine incorporation assays and to induce apoptosis directly, while other anti-CD19 and CD20 antibodies do not (Maloney et al. Blood 88(10):637a (1996)). Synergy between RITUXAN® and chemotherapies and toxins has also been observed experimentally. In particular, RITUXAN® sensitizes drug-resistant human B cell lymphoma cell lines to the cytotoxic effects of doxorubicin, CDDP, VP-16, diphtheria toxin and ricin (Demidem et al. Cancer Chemotherapy & Radiopharmaceuticals 12(3): 177-186 (1997)). In vivo preclinical studies have shown that RITUXAN® depletes B cells from the peripheral blood, lymph nodes, and bone marrow of cynomolgus monkeys, presumably through complement and cell-mediated processes (Reff et al. Blood 83(2):435-445 (1994)). Summary of the Invention The present invention provides, in a first aspect, a method of treating an autoimmune disease in a mammal comprising administering to the mammal a therapeutically effective amount of an antagonist which binds to a B cell surface marker. In a further aspect, the present invention pertains to an article of manufacture comprising a container and a composition contained therein, wherein the composition comprises an antagonist M inch binds to a B cell surface marker, and further comprising a package insert instructing the user of the composition to treat a patient having or predisposed to an autoimmune disease. Detailed Description of the Preferred Embodiments I. Definitions A "B cell surface marker" herein is an antigen expressed on the surface of a B cell which can be targeted with an antagonist which binds thereto. Exemplary B cell surface markers include the CD 10, CD 19, CD20, CD21 , CD22, CD23, CD24, CD37, CD53, CD72, CD73, CD74, CDw75, CDw76, CD77, CDw78, CD79a, CD79b, CD80, CD81, CD82, CD83, CDw84, CD85 and CD86 leukocyte surface markers. The B cell surface marker of particular interest is preferentially expressed on B cells compared to other non-B cell tissues of a mammal and may be expressed on both precursor B cells and mature B cells. In one embodiment, the marker is one, like CD20 or CD 19, which is found on B cells throughout differentiation of the lineage from the stem cell stage up to a point just prior to terminal differentiation into plasma cells. The preferred B cell surface markers herein are CD 19 and CD20. The "CD20" antigen is a ~ 35 kDa, non-glycosylated phosphoprotein found on the surface of greater than 90% of B cells from peripheral blood or lymphoid organs. CD20 is expressed during early pre-B cell development and remains until plasma cell differentiation CD20 is present on both normal B cells as well as malignant B cells Other names for CD20 in the literature include "B-lymphocyte-restπcted antigen" and "Bp35" The CD20 antigen is descπbed in Clark et al PNAS (USA) 82 1766 (1985), for example The "CD 19" antigen refers to a ~90kDa antigen identified, for example, by the HD237-CD19 or B4 antibody (Kiesel et al Leukemia Research 11, 12 1119 (1987)) Like CD20, CD 19 is found on cells throughout differentiation of the lineage from the stem cell stage up to a point just pπor to terminal differentiation into plasma cells Bmdmg of an antagonist to CD 19 may cause lnternahzation of the CD 19 antigen An "autoimmune disease" herein is a non-malignant disease or disorder arising from and directed against an individual's own tissues The autoimmune diseases herem specifically exclude malignant or cancerous diseases or conditions, especially excludmg B cell lymphoma, acute lymphoblastic leukemia (ALL), chronic lymphocytic leukemia (CLL), Hairy cell leukemia and chronic myeloblastic leukemia Examples of autoimmune diseases or disorders mclude, but are not limited to, inflammatory responses such as inflammatory skin diseases including psoπasis and dermatitis {e g atopic dermatitis), systemic scleroderma and sclerosis, responses associated with inflammatory bowel disease (such as Crohn's disease and ulcerative colitis), respiratory distress syndrome (including adult respiratory distress syndrome, ARDS), dermatitis, meningitis, encephalitis, uveitis, colitis, glomerulonephπtis, allergic conditions such as eczema and asthma and other conditions involving infiltration of T cells and chronic inflammatory responses, atherosclerosis, leukocyte adhesion deficiency, rheumatoid arthπtis, systemic lupus erythematosus (SLE), diabetes melhtus {e g Type I diabetes melhtus or insulin dependent diabetes mel tis), multiple sclerosis, Reynaud's syndrome, autoimmune thyroiditis, allergic encephalomyehtis, Sjorgen's syndrome, juvenile onset diabetes, and immune responses associated with acute and delayed hypersensitivity mediated by cytokines and T-lymphocytes typically found in tuberculosis, sarcoidosis, polymyositis, granulomatosis and vascuhtis, pernicious anemia (Addison's disease), diseases involving leukocyte diapedesis, central nervous system (CNS) inflammatory disorder, multiple organ injury syndrome, hemolytic anemia (including, but not limited to cryoglobinemia or Coombs positive anemia) , myasthema gravis, antigen-antibody complex mediated diseases, anti-glomerular basement membrane disease, antiphospho pid syndrome, allergic neuritis, Graves' disease, Lambert-Eaton myasthenic syndrome, pemphigoid bullous, pemphigus, autoimmune polyendocπnopathies, Reiter's disease, stiff-man syndrome, Behcet disease, giant cell arteπtis, immune complex nephritis, IgA nephropathy, IgM polyneuropathies, immune thrombocytopemc purpura (ITP) or autoimmune thrombocytopenia etc An "antagonist" is a molecule which, upon bmding to a B cell surface marker, destroys or depletes B cells in a mammal and/or interferes with one or more B cell functions, e g by reducing or preventing a humoral response elicited by the B cell The antagonist preferably is able to deplete B cells {ι e reduce circulating B cell levels) m a mammal treated therewith Such depletion may be achieved via various mechanisms such antibody-dependent cell- mediated cytotoxicity (ADCC) and/or complement dependent cytotoxicity (CDC), inhibition of B cell proliferation and or induction of B cell death (e g via apoptosis) Antagonists included within the scope of the present invention mclude antibodies, synthetic or native sequence peptides and small molecule antagonists which bind to the B cell marker, optionally conjugated with or fused to a cytotoxic agent The preferred antagonist comprises an antibody "Antibody-dependent cell-mediated cytotoxicity" and "ADCC" refer to a cell-mediated reaction in which nonspecific cytotoxic cells that express Fc receptors (FcRs) {e g Natural Killer (NK) cells, neutrophils, and macrophages) recognize bound antibody on a target cell and subsequently cause lysis of the target cell The pπmary cells for mediating ADCC, NK cells, express FcγRIII only, whereas monocytes express FcγRI, FcγRII and FcγRIII FcR expression on hematopoietic cells in summarized is Table 3 on page 464 of Ravetch and Kmet, Annu Rev Immunol 9:457-92 (1991). To assess ADCC activity of a molecule of interest, an in vitro ADCC assay, such as that described in US Patent No. 5,500,362 or 5,821,337 may be performed. Useful effector cells for such assays include peripheral blood mononuclear cells (PBMC) and Natural Killer (NK) cells. Alternatively, or additionally, ADCC activity of the molecule of interest may be assessed in vivo, e.g., in a animal model such as that disclosed in Clynes et al. PNAS (USA) 95:652-656 (1998). "Human effector cells" are leukocytes which express one or more FcRs and perform effector functions. Preferably, the cells express at least FcγRIII and carry out ADCC effector function. Examples of human leukocytes which mediate ADCC include peripheral blood mononuclear cells (PBMC), natural killer (NK) cells, monocytes, cytotoxic T cells and neutrophils; with PBMCs and NK cells being preferred. The terms "Fc receptor" or "FcR" are used to describe a receptor that binds to the Fc region of an antibody. The preferred FcR is a native sequence human FcR. Moreover, a preferred FcR is one which binds an IgG antibody (a gamma receptor) and includes receptors of the FcγRI, FcγRII, and Fcγ RIII subclasses, including allelic variants and alternatively spliced forms of these receptors. FcγRII receptors include FcγRIIA (an "activating receptor") and FcγRIIB (an "inhibiting receptor"), which have similar amino acid sequences that differ primarily in the cytoplasmic domains thereof. Activating receptor FcγRIIA contains an immunoreceptor tyrosine-based activation motif (ITAM) in its cytoplasmic domain. Inhibiting receptor FcγRIIB contains an immunoreceptor tyrosine-based inhibition motif (ITIM) in its cytoplasmic domain, (see Daeron, Annu. Rev. Immunol. 15:203-234 (1997)). FcRs are reviewed in Ravetch and Kinet, Annu. Rev. Immunol 9:457-92 ( 1991 ); Capel et al, Immunomethods 4:25-34 ( 1994); and de Haas et al., J. Lab. Clin. Med. 126:330-41 (1995). Other FcRs, including those to be identified in the future, are encompassed by the term "FcR" herein. The term also includes the neonatal receptor, FcRn, which is responsible for the transfer of maternal IgGs to the fetus (Guyer et al., J. Immunol. 117:587 (1976) and Kim et al., J. Immunol. 24:249 (1994)). "Complement dependent cytotoxicity" or "CDC" refer to the ability of a molecule to lyse a target in the presence of complement. The complement activation pathway is initiated by the binding of the first component of the complement system (Clq) to a molecule {e.g. an antibody) complexed with a cognate antigen. To assess complement activation, a CDC assay, e.g. as described in Gazzano-Santoro et al., J. Immunol. Methods 202:163 (1996), may be performed. "Growth inhibitory" antagonists are those which prevent or reduce proliferation of a cell expressing an antigen to which the antagonist binds. For example, the antagonist may prevent or reduce proliferation of B cells in vitro and/or in vivo. Antagonists which "induce apoptosis" are those which induce programmed cell death, e.g. of a B cell, as determined by standard apoptosis assays, such as binding of annexin V, fragmentation of DNA, cell shrinkage, dilation of endoplasmic reticulum, cell fragmentation, and or formation of membrane vesicles (called apoptotic bodies). The term "antibody" herein is used in the broadest sense and specifically covers intact monoclonal antibodies, polyclonal antibodies, multispecific antibodies (e.g. bispecific antibodies) formed from at least two intact antibodies, and antibody fragments so long as they exhibit the desired biological activity. "Antibody fragments" comprise a portion of an intact antibody, preferably comprising the antigen-binding or variable region thereof. Examples of antibody fragments include Fab, Fab', F(ab') 2 , and Fv fragments; diabodies; linear antibodies; single-chain antibody molecules; and multispecific antibodies formed from antibody fragments. "Native antibodies" are usually heterotetrameric glycoproteins of about 150,000 daltons, composed of two identical light (L) chains and two identical heavy (H) chams Each light cham is linked to a heavy chain by one covalent disulfide bond, while the number of disulfide linkages varies among the heavy chams of different lmmunoglobulin isotypes Each heavy and light cham also has regularly spaced intrachain disulfide bπdges Each heavy cham has at one end a vaπable domam ( V H ) followed by a number of constant domains Each light chain has a vaπable domam at one end (V L ) and a constant domam at its other end, the constant domain of the light cham is aligned with the first constant domam of the heavy chain, and the light-chain variable domam is aligned with the vanable domam of the heavy chain Particular ammo acid residues are believed to form an mterface between the light chain and heavy cham vaπable domains The term "vaπable" refers to the fact that certain portions of the vaπable domains differ extensively in sequence among antibodies and are used in the bmdmg and specificity of each particular antibody for its particular antigen However, the vaπability is not evenly distributed throughout the vaπable domams of antibodies It is concentrated in three segments called hypervaπable regions both in the light cham and the heavy chain vaπable domains The more highly conserved portions of variable domams are called the framework regions (FRs) The variable domains of native heavy and light chains each compπse four FRs, largely adoptmg a β-sheet configuration, connected by three hypervaπable regions, which form loops connecting, and in some cases forming part of, the β- sheet structure The hypervaπable regions in each chain are held together in close proximity by the FRs and, with the hypervaπable regions from the other cham, contπbute to the formation of the antigen-binding site of antibodies (see Kabat et al , Sequences of Proteins of Immunological Interest, 5th Ed Public Health Service, National Institutes of Health, Bethesda, MD (1991)) The constant domains are not involved directly in bmding an antibody to an antigen, but exhibit vaπous effector functions, such as participation of the antibody in antibody dependent cellular cytotoxicity (ADCC) Papain digestion of antibodies produces two identical antigen-binding fragments, called "Fab" fragments, each with a smgle antigen-bmdmg site, and a residual "Fc" fragment, whose name reflects its ability to crystallize readily Pepsm treatment yields an F(ab' 2 fragment that has two antigen-binding sites and is still capable of cross- linking antigen "F v" is the minimum antibody fragment which contams a complete antigen-recognition and antigen-binding site This region consists of a dimer of one heavy cham and one light chain vaπable domain m tight, non-covalent association It is in this configuration that the three hypervaπable regions of each variable domam interact to define an antigen-binding site on the surface of the V H -V L dimer Collectively, the six hypervaπable regions confer antigen- bmdmg specificity to the antibody However, even a single variable domain (or half of an Fv compπsing only three hypervaπable regions specific for an antigen) has the ability to recognize and bind antigen, although at a lower affinity than the entire binding site The Fab fragment also contains the constant domain of the light chain and the first constant domain (CHI) of the heavy cham Fab' fragments differ from Fab fragments by the addition of a few residues at the carboxy terminus of the heavy cham CHI domain including one or more cysteines from the antibody hinge region Fab'-SH is the designation herem for Fab' in which the cysteine resιdue(s) of the constant domams bear at least one free thiol group F(ab') 2 antibody fragments oπginally were produced as pairs of Fab' fragments which have hinge cysteines between them Other chemical couplmgs of antibody fragments are also known The "light chains" of antibodies (immunoglobuhns) from any vertebrate species can be assigned to one of two clearly distinct types, called kappa (K) and lambda (λ), based on the ammo acid sequences of their constant domains Depending on the amino acid sequence of the constant domain of their heavy chains, antibodies can be assigned to different classes. There are five major classes of intact antibodies: IgA, IgD, IgE, IgG, and IgM, and several of these may be further divided into subclasses (isotypes), e.g., IgGl , IgG2, IgG3, IgG4, IgA, and IgA2. The heavy-chain constant domains that correspond to the different classes of antibodies are called α, δ, ε, γ, and μ, respectively. The subunit structures and three-dimensional configurations of different classes of immunoglobulins are well known. " Single-chain Fv" or "scFv" antibody fragments comprise the V H and V L domains of antibody, wherein these domains are present in a single polypeptide chain. Preferably, the Fv polypeptide further comprises a polypeptide linker between the V H and V L domains which enables the scFv to form the desired structure for antigen binding. For a review of scFv see Plϋckthun in The Pharmacology of Monoclonal Antibodies, vol. 113, Rosenburg and Moore eds., Springer- Verlag, New York, pp. 269-315 (1994). The term "diabodies" refers to small antibody fragments with two antigen-binding sites, which fragments comprise a heavy-chain variable domain (V H ) connected to a light-chain variable domain (V L ) in the same polypeptide chain (V H - V L ). By using a linker that is too short to allow pairing between the two domains on the same chain, the domains are forced to pair with the complementary domains of another chain and create two antigen- binding sites. Diabodies are described more fully in, for example, EP 404,097; WO 93/11161; and Hollinger et al, Proc. Natl. Acad. Sci. USA, 90:6444-6448 (1993). The term "monoclonal antibody" as used herein refers to an antibody obtained from a population of substantially homogeneous antibodies, i.e., the individual antibodies comprising the population are identical except for possible naturally occurring mutations that may be present in minor amounts. Monoclonal antibodies are highly specific, being directed against a single antigenic site. Furthermore, in contrast to conventional (polyclonal) antibody preparations which typically include different antibodies directed against different determinants (epitopes), each monoclonal antibody is directed against a single determinant on the antigen. In addition to their specificity, the monoclonal antibodies are advantageous in that they are synthesized by the hybridoma culture, uncontaminated by other immunoglobulins. The modifier "monoclonal" indicates the character of the antibody as being obtained from a substantially homogeneous population of antibodies, and is not to be construed as requiring production of the antibody by any particular method. For example, the monoclonal antibodies to be used in accordance with the present invention may be made by the hybridoma method first described by Kohler et al, Nature, 256:495 (1975), or may be made by recombinant DNA methods (see, e.g., U.S. Patent No. 4,816,567). The "monoclonal antibodies" may also be isolated from phage antibody libraries using the techniques described in Clackson et al, Nature, 352:624-628 (1991) and Marks et al, J. Mol Biol, 222:581-597 (1991), for example. The monoclonal antibodies herein specifically include "chimeric" antibodies (immunoglobulins) in which a portion of the heavy and/or light chain is identical with or homologous to corresponding sequences in antibodies derived from a particular species or belonging to a particular antibody class or subclass, while the remainder of the chain(s) is identical with or homologous to corresponding sequences in antibodies derived from another species or belonging to another antibody class or subclass, as well as fragments of such antibodies, so long as they exhibit the desired biological activity (U.S. Patent No. 4,816,567; Morrison et al, Proc. Natl. Acad. Sci. USA, 81 :6851-6855 (1984)). Chimeric antibodies of interest herein include "primatized" antibodies comprising variable domain antigen- binding sequences derived from a non-human primate (e.g. Old World Monkey, such as baboon, rhesus or cynomolgus monkey) and human constant region sequences (US Pat No. 5,693,780). "Humanized" forms of non-human {e.g., murine) antibodies are chimeric antibodies that contain minimal sequence derived from non-human immunoglobulin. For the most part, humanized antibodies are human immunoglobulins (recipient antibody) in which residues from a hypervariable region of the recipient are replaced by residues from a hypervariable region of a non-human species (donor antibody) such as mouse, rat, rabbit or nonhuman primate having the desired specificity, affinity, and capacity. In some instances, framework region (FR) residues of the human immunoglobulin are replaced by corresponding non-human residues. Furthermore, humanized antibodies may comprise residues that are not found in the recipient antibody or in the donor antibody. These modifications are made to further refine antibody performance. In general, the humanized antibody will comprise substantially all of at least one, and typically two, variable domains, in which all or substantially all of the hypervariable loops correspond to those of a non-human immunoglobulin and all or substantially all of the FRs are those of a human immunoglobulin sequence. The humanized antibody optionally also will comprise at least a portion of an immunoglobulin constant region (Fc), typically that of a human immunoglobulin. For further details, see Jones etal, Nature 321:522-525 (1986); Riechmann etal., Nature 332:323-329 (1988); andPresta, Curr. Op. Struct. Biol 2:593-596 (1992). The term "hypervariable region" when used herein refers to the amino acid residues of an antibody which are responsible for antigen-binding. The hypervariable region comprises amino acid residues from a "complementarity determining region" or "CDR" (e.g. residues 24-34 (LI), 50-56 (L2) and 89-97 (L3) in the light chain variable domain and 31-35 (HI), 50-65 (H2) and 95-102 (H3) in the heavy chain variable domain; Kabat et al, Sequences of Proteins of Immunological Interest, 5th Ed. Public Health Service, National Institutes of Health, Bethesda, MD. ( 1991 )) and/or those residues from a "hypervariable loop" (e.g. residues 26-32 (L 1 ), 50-52 (L2) and 91-96 (L3) in the light chain variable domain and 26-32 (HI), 53-55 (H2) and 96-101 (H3) in the heavy chain variable domain; Chothia and Lesk /. Mol Biol. 196:901-917 (1987)). "Framework" or "FR" residues are those variable domain residues other than the hypervariable region residues as herein defined. An antagonist "which binds" an antigen of interest, e.g. a B cell surface marker, is one capable of binding that antigen with sufficient affinity and/or avidity such that the antagonist is useful as a therapeutic agent for targeting a cell expressing the antigen. Examples of antibodies which bind the CD20 antigen include: "C2B8" which is now called "rituximab" ("RITUXAN®") (US Patent No. 5,736,137, expressly incorporated herein by reference); the yttrium-[90]-labeled 2B8 murine antibody designated "Y2B8" (US Patent No. 5,736,137, expressly incorporated herein by reference); murine IgG2a "Bl" optionally labeled with 131 I to generate the " 131 I-B1" antibody (BEXXAR™) (US Patent No. 5,595,721, expressly incorporated herein by reference); murine monoclonal antibody "1F5" (Press et al. Blood 69(2):584-591 (1987)); "chimeric 2H7" antibody (US Patent No. 5,677,180, expressly incorporated herein by reference); and monoclonal antibodies L27, G28-2, 93-1B3, B-Cl or NU-B2 available from the International Leukocyte Typing Workshop (Valentine et al. , In: Leukocyte Typing III (McMichael, Ed., p.440, Oxford University Press (1987)). Examples of antibodies which bind the CD 19 antigen include the anti-CD 19 antibodies in Hekman et al. Cancer Immunol. Immunother. 32:364-372 (1991) and Vlasveld et al. Cancer Immunol. Immunother. 40:37-47 (1995); and the B4 antibody in Kiesel et al. Leukemia Research II, 12: 1119 (1987). The terms "rituximab" or "RITUXAN®" herein refer to the genetically engineered chimeric murine/human monoclonal antibody directed against the CD20 antigen and designated "C2B8" in US Patent No. 5,736,137, expressly incorporated herein by reference. The antibody is an IgG, kappa immunoglobulin containing murine light and heavy chain variable region sequences and human constant region sequences Rituximab has a bindmg affinity for the CD20 antigen of approximately 8 OnM An "isolated" antagonist is one which has been identified and separated and/or recovered from a component of its natural environment Contaminant components of its natural environment are matenals which would interfere with diagnostic or therapeutic uses for the antagonist, and may include enzymes, hormones, and other protemaceous or nonprotemaceous solutes In preferred embodiments, the antagonist will be puπfied (1) to greater than 95% by weight of antagonist as determmed by the Lowry method, and most preferably more than 99% by weight, (2) to a degree sufficient to obtam at least 15 residues of N-terminal or internal ammo acid sequence by use of a spinning cup sequenator, or (3) to homogeneity by SDS-PAGE under reducmg or nonreducmg conditions usmg Coomassie blue or, preferably, silver stam Isolated antagonist includes the antagonist in situ within recombinant cells since at least one component of the antagonist's natural environment will not be present Ordinarily, however, isolated antagonist will be prepared by at least one puπfication step "Mammal" for purposes of treatment refers to any animal classified as a mammal, including humans, domestic and farm animals, and zoo, sports, or pet animals, such as dogs, horses, cats, cows, etc Preferably, the mammal is human "Treatment" refers to both therapeutic treatment and prophylactic or preventative measures Those in need of treatment mclude those already with the disease or disorder as well as those in which the disease or disorder is to be prevented Hence, the mammal may have been diagnosed as having the disease or disorder or may be predisposed or susceptible to the disease The expression "therapeutically effective amount" refers to an amount of the antagonist which is effective for preventing, ameliorating or treating the autoimmune disease in question The term "immunosuppressive agent" as used herem for adjunct therapy refers to substances that act to suppress or mask the immune system of the mammal bemg treated herein This would include substances that suppress cytokine production, downregulate or suppress self-antigen expression, or mask the MHC antigens Examples of such agents mclude 2-amιno-6-aryl-5-substιtuted pynmidines (see U S Pat No 4,665,077, the disclosure of which is incorporated herein by reference), azathiopπne, cyclophosphamide, bromocryptine, danazol, dapsone, glutaraldehyde (which masks the MHC antigens, as described in U S Pat No 4,120,649), anti-idiotypic antibodies for MHC antigens and MHC fragments, cyclosponn A, steroids such as glucocorticosteroids, e g , predmsone, methylpredmsolone, and dexamethasone, cytokine or cytokine receptor antagonists including anti- interferon-γ, -β, or-α antibodies, anti-tumor necrosis factor-α antibodies, anti- tumor necrosis factor-β antibodies, anti- ιnterleukιn-2 antibodies and antι-IL-2 receptor antibodies, antι-LFA-1 antibodies, including anti-CDl la and anti- CD 18 antibodies, antι-L3T4 antibodies, heterologous anti-lymphocyte globulin, pan-T antibodies, preferably anti- CD3 or antι-CD4/CD4a antibodies, soluble peptide containing a LFA-3 binding domam (WO 90/08187 published 7/26/90), streptokinase, TGF-β, streptodornase, RNA or DNA from the host, FK506, RS-61443, deoxysperguahn, rapamycm, T-cell receptor (Cohen et al , U S Pat No 5,114,721), T-cell receptor fragments {Of neτetal . Science, 251 430-432 (1991), WO 90/11294, Ianeway, Natw e, 341 482 (1989), and WO 91/01133), and T cell receptor antibodies (EP 340,109) such as T10B9 The term "cytotoxic agent" as used herem refers to a substance that inhibits or prevents the function of cells 21 ] ] ι ]25 90 and/or causes destruction of cells The term is intended to include radioactive isotopes (e g At J J , Y , Re , Re , Sm , Bi , P and radioactive isotopes of Lu), chemotherapeutic agents, and toxins such as small molecule toxms or enzymatically active toxms of bacterial, fungal, plant or animal oπgin, or fragments thereof A "chemo therapeutic agent" is a chemical compound useful in the treatment of cancer. Examples of chemotherapeutic agents include alkylating agents such as thiotepa and cyclosphosphamide (CYTOXAN™); alkyl sulfonates such as busulfan, improsulfan and piposulfan; aziridines such as benzodopa, carboquone, meturedopa, and uredopa; ethylenimines and methylamelamines including altretamine, triethylenemelamine, trietylenephosphoramide, triethylenethiophosphaoramide and trimethylolomelamine; 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, ranimustine; antibiotics such as aclacinomysins, actinomycin, authramycin, azaserine, bleomycins, cactinomycin, calicheamicin, carabicin, carminomycin, carzinophilin, chromomycins, dactinomycin, daunorubicin, detorubicin, 6-diazo-5-oxo-L-norleucine, doxorubicin, epirubicin, esorubicin, idarubicin, marcellomycin, mitomycins, 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-mercaρtopurine, thiamiprine, thioguanine; pyrimidine analogs such as ancitabine, azacitidine, 6-azauridine, carmofur, cytarabine, dideoxyuridine, doxifluridine, enocitabine, floxuridine, 5-FU; androgens such as calusterone, dromostanolone propionate, epitiostanol, mepitiostane, testolactone; anti-adrenals such as aminoglutethimide, mitotane, trilostane; folic acid replenisher such as frolinic acid; aceglatone; aldophosphamide glycoside; aminolevulinic acid; amsacrine; bestrabucil; bisantrene; edatraxate; defo famine; demecolcine; diaziquone; elfornithine; elliptinium acetate; etoglucid; gallium nitrate; hydroxyurea; lentinan; lonidamine; mitoguazone; mitoxantrone; mopidamol; nitracrine; pentostatin; phenamet; pirarubicin; podophyllinic acid; 2-ethylhydrazide; procarbazine; PSK®; razoxane; sizofiran; spirogermanium; tenuazonic acid; triaziquone; 2, 2',2"-trichlorotriethylamine; urethan; vindesine; dacarbazine; mannomustine; mitobronitol; mitolactol; pipobroman; gacytosine; arabinoside ("Ara-C"); cyclophosphamide; thiotepa; taxoids, e.g. paclitaxel (TAXOL ® , Bristol-Myers Squibb Oncology, Princeton, NJ) and doxetaxel (TAXOTERE ® , Rhόne-Poulenc Rorer, Antony, France); chlorambucil; gemcitabine; 6-thioguanine; mercaptopurine; methotrexate; platinum analogs such as cisplatin and carboplatin; vinblastine; platinum; etoposide (VP-16); ifosfamide; mitomycin C; mitoxantrone; vincristine; vinorelbine; navelbine; novantrone; teniposide; daunomycin; aminopterin; xeloda; ibandronate; CPT-11; topoisomerase inhibitor RFS 2000; difluoromethylornithine (DMFO); retinoic acid; esperamicins; capecitabine; and pharmaceutically acceptable salts, acids or derivatives of any of the above. Also included in this definition are anti-hormonal agents that act to regulate or inhibit hormone action on tumors such as anti-estrogens including for example tamoxifen, raloxifene, aromatase inhibiting 4(5)-imidazoles, 4- hydroxytamoxifen, trioxifene, keoxifene, LY117018, onapristone, and toremifene (Fareston); and anti-androgens such as flutamide, nilutamide, bicalutamide, leuprolide, and goserelin; and pharmaceutically acceptable salts, acids or derivatives of any of the above. The term "cytokine" is a generic term for proteins released by one cell population which act on another cell as intercellular mediators. Examples of such cytokines are lymphokines, monokines, and traditional polypeptide hormones. Included among the cytokines are growth hormone such as human growth hormone, N-methionyl human growth hormone, and bovine growth hormone; parathyroid hormone; thyroxine; insulin; proinsulin; relaxin; prorelaxin; glycoprotein hormones such as follicle stimulating hormone (FSH), thyroid stimulating hormone (TSH), and luteinizing hormone (LH); hepatic growth factor; fibroblast growth factor; prolactin; placental lactogen; tumor necrosis factor-α and -β; mullerian-inhibiting substance; mouse gonadotropin-associated peptide; inhibin; activin; vascular endothelial growth factor; integrin; thrombopoietin (TPO); nerve growth factors such as NGF-β; platelet- growth factor; transforming growth factors (TGFs) such as TGF-α and TGF-β; insulin-like growth factor-I and -II; erythropoietin (EPO); osteoinductive factors; interferons such as interferon-α, -β, and -γ; colony stimulating factors (CSFs) such as macrophage-CSF (M-CSF); granulocyte-macrophage-CSF (GM-CSF); and granulocyte-CSF (G- CSF); interleukins (ILs) such as IL-1, IL-lα, IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-8, IL-9, IL-11, IL-12, IL-15; a tumor necrosis factor such as TNF-α or TNF-β; and other polypeptide factors including LIF and kit ligand (KL). As used herein, the term cytokine includes proteins from natural sources or from recombinant cell culture and biologically active equivalents of the native sequence cytokines. The term "prodrug" as used in this application refers to a precursor or derivative form of a pharmaceutically active substance that is less cytotoxic to tumor cells compared to the parent drug and is capable of being enzymatically activated or converted into the more active parent form. See, e.g., Wilman, "Prodrugs in Cancer Chemotherapy" Biochemical Society Transactions, 14, pp. 375-382, 615th Meeting Belfast (1986) and Stella etal, "Prodrugs: A Chemical Approach to Targeted Drug Delivery," Directed Drug Delivery, Borchardt et al, (ed.), pp. 247-267, Humana Press (1985). The prodrugs of this invention include, but are not limited to, phosphate-containing prodrugs, thiophosphate-containing prodrugs, sulfate-containing prodrugs, peptide-containing prodrugs, D-amino acid-modified prodrugs, glycosylated prodrugs, β-lactam-containing prodrugs, optionally substituted phenoxyacetamide-containing prodrugs or optionally substituted phenylacetamide-containing prodrugs, 5- fluorocytosine and other 5-fluorouridine prodrugs which can be converted into the more active cytotoxic free drug. Examples of cytotoxic drugs that can be derivatized into a prodrug form for use in this invention include, but are not limited to, those chemotherapeutic agents described above. A "liposome" is a small vesicle composed of various types of lipids, phospholipids and/or surfactant which is useful for delivery of a drug (such as the antagonists disclosed herein and, optionally, a chemotherapeutic agent) to a mammal. The components of the liposome are commonly arranged in a bilayer formation, similar to the lipid arrangement of biological membranes. The term "package insert" is used to refer to instructions customarily included in commercial packages of therapeutic products, that contain information about the indications, usage, dosage, administration, contraindications and/or warnings concerning the use of such therapeutic products. II. Production of Antagonists The methods and articles of manufacture of the present invention use, or incorporate, an antagonist which binds to a B cell surface marker. Accordingly, methods for generating such antagonists will be described here. The B cell surface marker to be used for production of, or screening for, antagonist(s) may be, e.g., a soluble form of the antigen or a portion thereof, containing the desired epitope. Alternatively, or additionally, cells expressing the B cell surface marker at their cell surface can be used to generate, or screen for, antagonist(s). Other forms of the B cell surface marker useful for generating antagonists will be apparent to those skilled in the art. Preferably, the B cell surface marker is the CD 19 or CD20 antigen. While the preferred antagonist is an antibody, antagonists other than antibodies are contemplated herein. For example, the antagonist may comprise a small molecule antagonist optionally fused to, or conjugated with, a cytotoxic agent (such as those described herein). Libraries of small molecules may be screened against the B cell surface marker of interest herein in order to identify a small molecule which binds to that antigen. The small molecule may further be screened for its antagonistic properties and/or conjugated with a cytotoxic agent. The antagonist may also be a peptide generated by rational design or by phage display (see, e.g., WO98/35036 published 13 August 1998). In one embodiment, the molecule of choice may be a "CDR mimic" or antibody analogue designed based on the CDRs of an antibody. While such peptides may be antagonistic by themselves, the peptide may optionally be fused to a cytotoxic agent so as to add or enhance antagonistic properties of the peptide. A description follows as to exemplary techniques for the production of the antibody antagonists used in accordance with the present invention. (i) Polyclonal antibodies Polyclonal antibodies are preferably raised in animals by multiple subcutaneous (sc) or intraperitoneal (ip) injections of the relevant antigen and an adjuvant. It may be useful to conjugate the relevant antigen to a protein that is immunogenic in the species to be immunized, e.g., keyhole limpet hemocyanin, serum albumin, bovine thyroglobulin, or soybean trypsin inhibitor using a bifunctional or derivatizing agent, for example, maleimidobenzoyl sulfosuccinimide ester (conjugation through cysteine residues), N-hydroxysuccinimide (through lysine residues), glutaraldehyde, succinic anhydride, SOCl 2 , or R N=C=NR, where R and R are different alkyl groups. Animals are immunized against the antigen, immunogenic conjugates, or derivatives by combining, e.g., 100 μg or 5 μg of the protein or conjugate (for rabbits or mice, respectively) with 3 volumes of Freund's complete adjuvant and injecting the solution intradermally at multiple sites. One month later the animals are boosted with 1/5 to 1/10 the original amount of peptide or conjugate in Freund's complete adjuvant by subcutaneous injection at multiple sites. Seven to 14 days later the animals are bled and the serum is assayed for antibody titer. Animals are boosted until the titer plateaus. Preferably, the animal is boosted with the conjugate of the same antigen, but conjugated to a different protein and/or through a different cross-linking reagent. Conjugates also can be made in recombinant cell culture as protein fusions. Also, aggregating agents such as alum are suitably used to enhance the immune response. (ii) Monoclonal antibodies Monoclonal antibodies are obtained from a population of substantially homogeneous antibodies, i.e., the individual antibodies comprising the population are identical except for possible naturally occurring mutations that may be present in minor amounts. Thus, the modifier "monoclonal" indicates the character of the antibody as not being a mixture of discrete antibodies. For example, the monoclonal antibodies may be made using the hybridoma method first described by Kohler et al, Nature, 256:495 (1975), or may be made by recombinant DNA methods (U.S. Patent No. 4,816,567). In the hybridoma method, a mouse or other appropriate host animal, such as a hamster, is immunized as hereinabove described to elicit lymphocytes that produce or are capable of producing antibodies that will specifically bind to the protein used for immunization. Alternatively, lymphocytes may be immunized in vitro. Lymphocytes then are fused with myeloma cells using a suitable fusing agent, such as polyethylene glycol, to form a hybridoma cell (Goding, Monoclonal Antibodies: Principles and Practice, pp.59-103 (Academic Press, 1986)). The hybridoma cells thus prepared are seeded and grown in a suitable culture medium that preferably contains one or more substances that inhibit the growth or survival of the unfused, parental myeloma cells. For example, if the parental myeloma cells lack the enzyme hypoxanthine guanine phosphoribosyl transferase (HGPRT or HPRT), the culture medium for the hybridomas typically will include hypoxanthine, aminopterin, and thymidine (HAT medium), which substances prevent the growth of HGPRT-deficient cells. Preferred myeloma cells are those that fuse efficiently, support stable high-level production of antibody by the selected antibody-producing cells, and are sensitive to a medium such as HAT medium Among these, preferred myeloma cell lines are muπne myeloma lmes, such as those derived from MOPC-21 and MPC-11 mouse tumors available from the Salk Institute Cell Distribution Center, San Diego, California USA, and SP-2 or X63-Ag8-653 cells available from the Amencan Type Culture Collection, Rockville, Maryland USA Human myeloma and mouse- human heteromyeloma cell lmes also have been descπbed for the production of human monoclonal antibodies (Kozbor, J Immunol , 133 3001 (1984), Brodeur et al , Monoclonal Antibody Production Techniques and Applications, pp 51-63 (Marcel Dekker, Inc , New York, 1987)) Culture medium in which hybridoma cells are growmg is assayed for production of monoclonal antibodies directed against the antigen Preferably, the binding specificity of monoclonal antibodies produced by hybridoma cells is determined by immunoprecipitation or by an in vitro bmding assay, such as radioimmunoassay (RIA) or enzyme-linked lmmunoabsorbent assay (ELISA) The binding affinity of the monoclonal antibody can, for example, be determined by the Scatchard analysis of Munson et al , Anal Biochem , 107 220 (1980) After hybridoma cells are identified that produce antibodies of the desired specificity, affinity, and/or activity, the clones may be subcloned by limiting dilution procedures and grown by standard methods (Goding, Monoclonal Antibodies Principles and Practice, pp 59-103 (Academic Press, 1986)) Suitable culture media for this purpose include, for example, D-MEM or RPMI- 1640 medium In addition, the hybπdoma cells may be grown in vivo as ascites tumors m an animal The monoclonal antibodies secreted by the subclones are suitably separated from the culture medium, ascites fluid, or serum by conventional immunoglobulin purification procedures such as, for example, protein A-Sepharose, hydroxylapatite chromatography, gel electrophoresis, dialysis, or affinity chromatography DNA encodmg the monoclonal antibodies is readily isolated and sequenced usmg conventional procedures {e g , by usmg ohgonucleotide probes that are capable of bindmg specifically to genes encoding the heavy and light chams of muπne antibodies) The hybridoma cells serve as a preferred source of such DNA Once isolated, the DNA may be placed mto expression vectors, which are then transfected into host cells such as E coh cells, simian COS cells, Chmese Hamster Ovary (CHO) cells, or myeloma cells that do not otherwise produce immunoglobulin protein, to obtam the synthesis of monoclonal antibodies m the recombinant host cells Review articles on recombmant expression m bacteπa of DNA encoding the antibody mclude Skerra et al , Curr Opinion in Immunol , 5 256-262 (1993) and Pluckthun, Immunol Revs , 130 151-188 (1992) In a further embodiment, antibodies or antibody fragments can be isolated from antibody phage hbraπes generated usmg the techniques descπbed in McCafferty et al , Nature, 348 552-554 (1990) Clackson et al , Nature, 352 624-628 (1991) and Marks etal , J Mol Biol , 222 581-597 (1991) describe the isolation of murine and human antibodies, respectively, usmg phage hbraπes Subsequent publications describe the production of high affinity (nM range) human antibodies by chain shuffling (Marks et al , Bio/Technology, 10 779-783 (1992)), as well as combinatorial infection and in vivo recombination as a strategy for constructing very large phage libraries (Waterhouse et al , Nuc Acids Res , 21 2265-2266 (1993)) Thus, these techniques are viable alternatives to traditional monoclonal antibody hybπdoma techniques for isolation of monoclonal antibodies The DNA also may be modified, for example, by substituting the coding sequence for human heavy- and light-chain constant domains m place of the homologous muπne sequences (U S Patent No 4,816,567, Morrison, etal , Proc Natl Acad Sci USA, SI 6851 (1984)), or by covalently joining to the immunoglobulin coding sequence all or part of the codmg sequence for a non- immunoglobulin polypeptide Typically such non- immunoglobulin polypeptides are substituted for the constant domams of an antibody, or they are substituted for the vaπable domains of one antigen-combmmg site of an antibody to create a chimeπc bivalent antibody comprising one antigen-combining site havmg specificity for an antigen and another antigen- combining site having specificity for a different antigen (in) Humanized antibodies Methods for humamzmg non-human antibodies have been descnbed m the art Preferably, a humanized antibody has one or more ammo acid residues introduced mto it from a source which is non-human These non- human ammo acid residues are often referred to as "import" residues, which are typically taken from an "import" vanable domam Humanization can be essentially performed following the method of Wmter and co-workers (Jones et al , Nature, 321 522-525 (1986), Riechmann et al , Nature, 332 323-327 (1988), Verhoeyen et al , Science, 239 1534- 1536 ( 1988)), by substituting hypervaπable region sequences for the corresponding sequences of a human antibody Accordingly, such "humanized" antibodies are chimeric antibodies (U S Patent No 4,816,567) wherein substantially less than an intact human vaπable domain has been substituted by the corresponding sequence from a non-human species In practice, humanized antibodies are typically human antibodies in which some hypervaπable region residues and possibly some FR residues are substituted by residues from analogous sites m rodent antibodies The choice of human vaπable domains, both light and heavy, to be used in making the humanized antibodies is very important to reduce antigenicity According to the so-called "best-fit" method, the sequence of the variable domain of a rodent antibody is screened agamst the entire library of known human variable-domain sequences The human sequence which is closest to that of the rodent is then accepted as the human framework region (FR) for the humanized antibody (Sims et al , J Immunol , 151 2296 (1993), Chothia et al , J Mol Biol , 196 901 (1987)) Another method uses a particular framework region derived from the consensus sequence of all human antibodies of a particular subgroup of light or heavy chains The same framework may be used for several different humanized antibodies (Carter et al , Proc Natl Acad Sci USA, 89 4285 (1992), Presta et al , J Immunol , 151 2623 (1993)) It is further important that antibodies be humanized with retention of high affinity for the antigen and other favorable biological properties To achieve this goal, according to a prefeπed method, humanized antibodies are prepared by a process of analysis of the parental sequences and vaπous conceptual humanized products using three- dimensional models of the parental and humanized sequences Three-dimensional immunoglobulin models are commonly available and are familiar to those skilled in the art Computer programs are available which illustrate and display probable three-dimensional conformational structures of selected candidate immunoglobulin sequences Inspection of these displays permits analysis of the likely role of the residues in the functioning of the candidate immunoglobulin sequence, i e , the analysis of residues that influence the ability of the candidate immunoglobulin to bind its antigen In this way, FR residues can be selected and combmed from the recipient and import sequences so that the desired antibody charactenstic, such as increased affinity for the target antιgen(s), is achieved In general, the hypervariable region residues are directly and most substantially involved in influencing antigen bmdmg (iv) Human antibodies As an alternative to humanization, human antibodies can be generated For example, it is now possible to produce transgenic animals {e g , mice) that are capable, upon immunization, of producmg a full repertoire of human antibodies m the absence of endogenous immunoglobulin production For example, it has been descnbed that the homozygous deletion of the antibody heavy-chain joining region (J H ) gene in chimeric and germ-line mutant mice results in complete inhibition of endogenous antibody production. Transfer of the human germ-line immunoglobulin gene array in such germ-line mutant mice will result in the production of human antibodies upon antigen challenge. See, e.g., Jakobovits et al, Proc. Natl. Acad. Sci. USA, 90:2551 (1993); Jakobovits et al, Nature, 362:255-258 (1993); Bruggermann et al, Year inlmmuno., 7:33 (1993); and US PatentNos. 5,591,669, 5,589,369 and 5,545,807. Alternatively, phage display technology (McCafferty et al, Nature 348:552-553 (1990)) can be used to produce human antibodies and antibody fragments in vitro, from immunoglobulin variable (V) domain gene repertoires from unimmunized donors. According to this technique, antibody V domain genes are cloned in-frame into either a major or minor coat protein gene of a filamentous bacteriophage, such as M13 or fd, and displayed as functional antibody fragments on the surface of the phage particle. Because the filamentous particle contains a single-stranded DNA copy of the phage genome, selections based on the functional properties of the antibody also result in selection of the gene encoding the antibody exhibiting those properties. Thus, the phage mimics some of the properties of the B cell. Phage display can be performed in a variety of formats; for their review see, e.g., Johnson, Kevin S. and Chiswell, David 1., Current Opinion in Structural Biology 3:564-571 (1993). Several sources of V-gene segments can be used for phage display. Clackson etal, Nature, 352:624-628 (1991) isolated a diverse array of anti-oxazolone antibodies from a small random combinatorial library of V genes derived from the spleens of immunized mice. A repertoire of V genes from unimmunized human donors can be constructed and antibodies to a diverse array of antigens (including self-antigens) can be isolated essentially following the techniques described by Marks et al, J. Mol Biol. 222:581-597 (1991), or Griffith et al, EMBO J. 12:725-734 (1993). See, also, US Patent Nos. 5,565,332 and 5,573,905. Human antibodies may also be generated by in vitro activated B cells (see US Patents 5,567,610 and 5,229,275). (v) Antibody fragments Various techniques have been developed for the production of antibody fragments. Traditionally, these fragments were derived via proteolytic digestion of intact antibodies (see, e.g., Morimoto et al, Journal of Biochemical and Biophysical Methods 24: 107-117 (1992) and Brennan ef at, Science, 229:81 (1985)). However, these fragments can now be produced directly by recombinant host cells. For example, the antibody fragments can be isolated from the antibody phage libraries discussed above. Alternatively, Fab ' -SH fragments can be directly recovered from E. coli and chemically coupled to form F(ab') 2 fragments (Carter etal, Bio/Technology 10 : 163 - 167 (1992)). According to another approach, F(ab') 2 fragments can be isolated directly from recombinant host cell culture. Other techniques for the production of antibody fragments will be apparent to the skilled practitioner. In other embodiments, the antibody of choice is a single chain Fv fragment (scFv). See WO 93/16185; US Patent No. 5,571,894; and US Patent No. 5,587,458. The antibody fragment may also be a "linear antibody", e.g., as described in US Patent 5,641,870 for example. Such linear antibody fragments may be monospecific or bispecific. (vi) Bispecific antibodies Bispecific antibodies are antibodies that have binding specificities for at least two different epitopes. Exemplary bispecific antibodies may bind to two different epitopes of the B cell surface marker. Other such antibodies may bind a first B cell marker and further bind a second B cell surface marker. Alternatively, an anti-B cell marker binding arm may be combined with an arm which binds to a triggering molecule on a leukocyte such as a T-cell receptor molecule {e.g. CD2 or CD3), or Fc receptors for IgG (FcγR), such as FcγRI (CD64), FcγRII (CD32) and FcγRIII (CD 16) so as to focus cellular defense mechanisms to the B cell. Bispecific antibodies may also be used to localize cytotoxic agents to the B cell. These antibodies possess a B cell marker-binding arm and an arm which binds the cytotoxic agent {e.g. saporin, anti-interferon-α, vinca alkaloid, ricin A chain, methotrexate or radioactive isotope hapten). Bispecific antibodies can be prepared as full length antibodies or antibody fragments {e.g. F(ab') 2 bispecific antibodies). Methods for making bispecific antibodies are known in the art. Traditional production of full length bispecific antibodies is based on the coexpression of two immunoglobulin heavy chain-light chain pairs, where the two chains have different specificities (Millstein et al, Nature, 305:537-539 (1983)). Because of the random assortment of immunoglobulin heavy and light chains, these hybridomas (quadromas) produce a potential mixture of 10 different antibody molecules, of which only one has the correct bispecific structure. Purification of the correct molecule, which is usually done by affinity chromatography steps, is rather cumbersome, and the product yields are low. Similar procedures are disclosed in WO 93/08829, and in Traunecker et al, EMBO J., 10:3655-3659 (1991). According to a different approach, antibody variable domains with the desired binding specificities (antibody-antigen combining sites) are fused to immunoglobulin constant domain sequences. The fusion preferably is with an immunoglobulin heavy chain constant domain, comprising at least part of the hinge, CH2, and CH3 regions. It is preferred to have the first heavy-chain constant region (CHI) containing the site necessary for light chain binding, present in at least one of the fusions. DNAs encoding the immunoglobulin heavy chain fusions and, if desired, the immunoglobulin light chain, are inserted into separate expression vectors, and are co-transfected into a suitable host organism. This provides for great flexibility in adjusting the mutual proportions of the three polypeptide fragments in embodiments when unequal ratios of the three polypeptide chains used in the construction provide the optimum yields. It is, however, possible to insert the coding sequences for two or all three polypeptide chains in one expression vector when the expression of at least two polypeptide chains in equal ratios results in high yields or when the ratios are of no particular significance. In a preferred embodiment of this approach, the bispecific antibodies are composed of a hybrid immunoglobulin heavy chain with a first binding specificity in one arm, and a hybrid immunoglobulin heavy chain- light chain pair (providing a second binding specificity) in the other arm. It was found that this asymmetric structure facilitates the separation of the desired bispecific compound from unwanted immunoglobulin chain combinations, as the presence of an immunoglobulin light chain in only one half of the bispecific molecule provides for a facile way of separation. This approach is disclosed in WO 94/04690. For further details of generating bispecific antibodies see, for example, Suresh et al, Methods in Enzymology, 121:210 (1986). According to another approach described in US Patent No. 5,731,168, the interface between a pair of antibody molecules can be engineered to maximize the percentage of heterodimers which are recovered from recombinant cell culture. The preferred interface comprises at least a part of the C H 3 domain of an antibody constant domain. In this method, one or more small amino acid side chains from the interface of the first antibody molecule are replaced with larger side chains (e.g. tyrosine or tryptophan). Compensatory "cavities" of identical or similar size to the large side chain(s) are created on the interface of the second antibody molecule by replacing large amino acid side chains with smaller ones {e.g. alanine or threonine). This provides a mechanism for increasing the yield of the heterodimer over other unwanted end-products such as homodimers. Bispecific antibodies include cross-linked or "heteroconjugate" antibodies. For example, one of the antibodies in the heteroconjugate can be coupled to avidin, the other to biotin. Such antibodies have, for example, been proposed to target immune system cells to unwanted cells (US Patent No.4,676,980), and for treatment of HIV infection (WO 91/00360, WO 92/200373, and EP 03089). Heteroconjugate antibodies may be made using any convenient cross-linking methods. Suitable cross-linking agents are well known in the art, and are disclosed in US Patent No. 4,676,980, along with a number of cross-linking techniques. Techniques for generating bispecific antibodies from antibody fragments have also been described in the literature. For example, bispecific antibodies can be prepared using chemical linkage. Brennan et al, Science, 229: 81 (1985) describe a procedure wherein intact antibodies are proteolytically cleaved to generate F(ab') 2 fragments. These fragments are reduced in the presence of the dithiol complexing agent sodium arsenite to stabilize vicinal dithiols and prevent intermolecular disulfide formation. The Fab' fragments generated are then converted to thionitrobenzoate (TNB) derivatives. One of the Fab'-TNB derivatives is then reconverted to the Fab'-thiol by reduction with mercaptoethylamine and is mixed with an equimolar amount of the other Fab'-TNB derivative to form the bispecific antibody. The bispecific antibodies produced can be used as agents for the selective immobilization of enzymes. Recent progress has facilitated the direct recovery of Fab'-SH fragments from E. coli, which can be chemically coupled to form bispecific antibodies. Shalaby et al, J. Exp. Med., 175: 217-225 (1992) describe the production of a fully humanized bispecific antibody F(ab') 2 molecule. Each Fab' fragment was separately secreted from E. coli and subjected to directed chemical coupling in vitro to form the bispecific antibody. The bispecific antibody thus formed was able to bind to cells overexpressing the ErbB2 receptor and normal human T cells, as well as trigger the lytic activity of human cytotoxic lymphocytes against human breast tumor targets. Various techniques for making and isolating bispecific antibody fragments directly from recombinant cell culture have also been described. For example, bispecific antibodies have been produced using leucine zippers. Kostelny et al, J. Immunol, 148(5): 1547-1553 (1992). The leucine zipper peptides from the Fos and Jun proteins were linked to the Fab' portions of two different antibodies by gene fusion. The antibody homodimers were reduced at the hinge region to form monomers and then re-oxidized to form the antibody heterodimers. This method can also be utilized for the production of antibody homodimers. The "diabody" technology described by Hollinger et al, Proc. Natl. Acad. Sci. USA, 90:6444-6448 (1993) has provided an alternative mechanism for making bispecific antibody fragments. The fragments comprise a heavy-chain variable domain (V H ) connected to a light-chain variable domain (V L ) by a linker which is too short to allow pairing between the two domains on the same chain. Accordingly, the V H and V L domains of one fragment are forced to pair with the complementary V L and V H domains of another fragment, thereby forming two antigen-binding sites. Another strategy for making bispecific antibody fragments by the use of single-chain Fv (sFv) dimers has also been reported. See Gruber et al, J. Immunol, 152:5368 (1994). Antibodies with more than two valencies are contemplated. For example, trispecific antibodies can be prepared. Tutt et al. J. Immunol. 147: 60 (1991). III. Conjugates and Other Modifications of the Antagonist The antagonist used in the methods or included in the articles of manufacture herein is optionally conjugated to a cytotoxic agent. Chemotherapeutic agents useful in the generation of such antagonist-cytotoxic agent conjugates have been described above. Conjugates of an antagonist and one or more small molecule toxins, such as a calicheamicin, a maytansine (US Patent No. 5,208,020), a trichothene, and CC1065 are also contemplated herein. In one embodiment of the invention, the antagonist is conjugated to one or more maytansine molecules {e.g. about 1 to about 10 maytansine molecules per antagonist molecule). Maytansine may, for example, be converted to May-SS-Me which may be reduced to May-SH3 and reacted with modified antagonist (Chari et al. Cancer Research 52: 127-131 (1992)) to generate a maytansinoid-antagonist conjugate. Alternatively, the antagonist is conjugated to one or more calicheamicin molecules. The calicheamicin family of antibiotics are capable of producing double-stranded DNA breaks at sub-picomolar concentrations. Structural analogues of calicheamicin which may be used include, but are not limited to, y λ , α 2 , α 3 , N-acetyl-γ, 1 , PSAG and θ (Hinman et al. Cancer Research 53: 3336-3342 (1993) and Lode et al. Cancer Research 58: 2925- 2928 (1998)). Enzymatically active toxins and fragments thereof which can be used include diphtheria A chain, nonbinding active fragments of diphtheria toxin, exotoxin A chain (from Pseudomonas aeruginosa), ricin A chain, abrin A chain, modeccin A chain, alpha-sarcin, Aleurites fordii proteins, dianthin proteins, Phytolaca americana proteins (PAPI, PAPII, and PAP-S), momordica charantia inhibitor, curcin, crotin, sapaonaria officinalis inhibitor, gelonin, mitogellin, restrictocin, phenomycin, enomycin and the tricothecenes. See, for example, WO 93/21232 published October 28, 1993. The present invention further contemplates antagonist conjugated with a compound with nucleolytic activity {e.g. a ribonuclease or a DNA endonuclease such as a deoxyribonuclease; DNase). A variety of radioactive isotopes are available for the production of radioconjugated antagonists. Examples m • c l lud A e A A .t211 , τ1 131 , τ1 1 5 , Λ YΛ90 , r R,e 186 , „ Re 188 , Sm 15 3 , T B D i-212 , T P,3 " 2 and , rad ,i.oact .i.ve i •sot .opes of r- τ Lu. Conjugates of the antagonist and cytotoxic agent may be made using a variety of bifunctional protein coupling agents such as N-succinimidyl-3-(2-pyridyldithiol) propionate (SPDP), succinimidyl-4-(N- maleimidomethyl) cyclohexane-1-carboxylate, iminothiolane (IT), bifunctional derivatives of imidoesters (such as dimethyl adipimidate HCL), active esters (such as disuccinimidyl suberate), aldehydes (such as glutareldehyde), bis- azido compounds (such as bis (p-azidobenzoyl) hexanediamine), bis-diazonium derivatives (such as bis-(p- diazoniumbenzoyl)-ethylenediamine), diisocyanates (such as tolyene 2,6-diisocyanate), and bis-active fluorine compounds (such as l,5-difluoro-2,4-dinitrobenzene). For example, a ricin immunotoxin can be prepared as described in Vitetta e? a/. Science238: 1098 (1987). Carbon- 14-labeled l-isothiocyanatobenzyl-3-methyldiethylene triaminepentaacetic acid (MX-DTPA) is an exemplary chelating agent for conjugation of radionucleotide to the antagonist. See W094/11026. The linker may be a "cleavable linker" facilitating release of the cytotoxic drug in the cell. For example, an acid-labile linker, peptidase-sensitive linker, dimethyl linker or disulfide-containing linker (Chari et al. Cancer Research 52: 127-131 (1992)) may be used. Alternatively, a fusion protein comprising the antagonist and cytotoxic agent may be made, e.g. by recombinant techniques or peptide synthesis. In yet another embodiment, the antagonist may be conjugated to a "receptor" (such streptavidin) for utilization in tumor pretargeting wherein the antagonist-receptor conjugate is administered to the patient, followed by removal of unbound conjugate from the circulation using a clearing agent and then administration of a "ligand" {e.g. avidin) which is conjugated to a cytotoxic agent (e.g. a radionucleotide). The antagonists of the present invention may also be conjugated with a prodrug-activating enzyme which converts a prodrug {e.g. a peptidyl chemotherapeutic agent, see WO81/01145) to an active anti-cancer drug. See, for example, WO 88/07378 and U.S. Patent No. 4,975,278. The enzyme component of such conjugates includes any enzyme capable of acting on a prodrug in such a way so as to covert it into its more active, cytotoxic form. Enzymes that are useful in the method of this invention include, but are not limited to, alkaline phosphatase useful for converting phosphate-containing prodrugs into free drugs; arylsulfatase useful for converting sulfate- containing prodrugs into free drugs; cytosine deaminase useful for converting non-toxic 5-fluorocytosine into the anti-cancer drug, 5-fluorouracil; proteases, such as serratia protease, thermolysin, subtilisin, carboxypeptidases and cathepsins (such as cathepsins B and L), that are useful for converting peptide-containing prodrugs into free drugs; D-alanylcarboxypeptidases, useful for converting prodrugs that contain D-amino acid substituents; carbohydrate- cleaving enzymes such as β-galactosidase and neuraminidase useful for converting glycosylated prodrugs into free drugs; β-lactamase useful for converting drugs derivatized with β-lactams into free drugs; and penicillin amidases, such as penicillin V amidase or penicillin G amidase, useful for converting drugs derivatized at their amine nitrogens with phenoxyacetyl or phenylacetyl groups, respectively, into free drugs. Alternatively, antibodies with enzymatic activity, also known in the art as "abzymes", can be used to convert the prodrugs of the invention into free active drugs (see, e.g., Massey, Nature 328: 457-458 (1987)). Antagonist-abzyme conjugates can be prepared as described herein for delivery of the abzyme to a tumor cell population. The enzymes of this invention can be covalently bound to the antagonist by techniques well known in the art such as the use of the heterobifunctional crosslinking reagents discussed above. Alternatively, fusion proteins comprising at least the antigen binding region of an antagonist of the invention linked to at least a functionally active portion of an enzyme of the invention can be constructed using recombinant DNA techniques well known in the art (see, e.g., Neuberger et al, Nature, 312: 604-608 (1984)). Other modifications of the antagonist are contemplated herein. For example, the antagonist may be linked to one of a variety of nonprotemaceous polymers, e.g. , polyethylene glycol, polypropylene glycol, polyoxyalkylenes, or copolymers of polyethylene glycol and polypropylene glycol. The antagonists disclosed herein may also be formulated as liposomes. Liposomes containing the antagonist are prepared by methods known in the art, such as described in Epstein et al, Proc. Natl. Acad. Sci. USA, 82:3688 (1985); Hwang etal, Proc. Natl Acad. Sci. USA, 77:4030 (1980); U.S. Pat. Nos.4,485,045 and 4,544,545; and W097/38731 published October 23, 1997. Liposomes with enhanced circulation time are disclosed in U.S. Patent No. 5,013,556. Particularly useful liposomes can be generated by the reverse phase evaporation method with a lipid composition comprising phosphatidylcholine, cholesterol and PEG-derivatizedphosphatidylethanolamine(PEG-PE). Liposomes are extruded through filters of defined pore size to yield liposomes with the desired diameter. Fab' fragments of an antibody of the present invention can be conjugated to the liposomes as described in Martin et al. J. Biol. Chem. 257: 286-288 (1982) via a disulfide interchange reaction. A chemotherapeutic agent is optionally contained within the liposome. See Gabizon et al. J. National Cancer Inst.81(19)1484 (1989). Amino acid sequence modification(s) of protein or peptide antagonists described herein are contemplated. For example, it may be desirable to improve the binding affinity and or other biological properties of the antagonist. Amino acid sequence variants of the antagonist are prepared by introducing appropriate nucleotide changes into the antagonist nucleic acid, or by peptide synthesis. Such modifications include, for example, deletions from, and/or insertions into and/or substitutions of, residues within the amino acid sequences of the antagonist. Any combination of deletion, insertion, and substitution is made to arrive at the final construct, provided that the final construct possesses the desired characteristics. The amino acid changes also may alter post-translational processes of the antagonist, such as changing the number or position of glycosylation sites. A useful method for identification of certain residues or regions of the antagonist that are preferred locations for mutagenesis is called "alanine scanning mutagenesis" as described by Cunningham and Wells Science, 244: 1081- 1085 (1989). Here, a residue or group of target residues are identified {e.g., charged residues such as arg, asp, his, lys, and glu) and replaced by a neutral or negatively charged amino acid (most preferably alanine or polyalanine) to affect the interaction of the amino acids with antigen. Those amino acid locations demonstrating functional sensitivity to the substitutions then are refined by introducing further or other variants at, or for, the sites of substitution. Thus, while the site for introducing an amino acid sequence variation is predetermined, the nature of the mutation per se need not be predetermined. For example, to analyze the performance of a mutation at a given site, ala scanning or random mutagenesis is conducted at the target codon or region and the expressed antagonist variants are screened for the desired activity. Amino acid sequence insertions include amino- and/or carboxyl-terminal fusions ranging in length from one residue to polypeptides containing a hundred or more residues, as well as intrasequence insertions of single or multiple amino acid residues. Examples of terminal insertions include an antagonist with an N-terminal methionyl residue or the antagonist fused to a cytotoxic polypeptide. Other insertional variants of the antagonist molecule include the fusion to the N- or C-terminus of the antagonist of an enzyme, or a polypeptide which increases the serum half-life of the antagonist. Another type of variant is an amino acid substitution variant. These variants have at least one amino acid residue in the antagonist molecule replaced by different residue. The sites of greatest interest for substitutional mutagenesis of antibody antagonists include the hypervariable regions, but FR alterations are also contemplated. Conservative substitutions are shown in Table 1 under the heading of "preferred substitutions". If such substitutions result in a change in biological activity, then more substantial changes, denominated "exemplary substitutions" in Table 1, or as further described below in reference to amino acid classes, may be introduced and the products screened. Table 1 Substantial modifications in the biological properties of the antagonist are accomplished by selecting substitutions that differ significantly in their effect on maintaining (a) the structure of the polypeptide backbone in the area of the substitution, for example, as a sheet or helical conformation, (b) the charge or hydrophobicity of the molecule at the target site, or (c) the bulk of the side chain. Naturally occurring residues are divided into groups based on common side-chain properties: (1) hydrophobic: norleucine, met, ala, val, leu, ile; (2) neutral hydrophilic: cys, ser, thr; (3) acidic: asp, glu; (4) basic: asn, gin, his, lys, arg; (5) residues that influence chain orientation: gly, pro; and (6) aromatic: tip, tyr, phe. Non-conservative substitutions will entail exchanging a member of one of these classes for another class. Any cysteine residue not involved in maintaining the proper conformation of the antagonist also may be substituted, generally with serine, to improve the oxidative stability of the molecule and prevent aberrant crosslinking. Conversely, cysteine bond(s) may be added to the antagonist to improve its stability (particularly where the antagonist is an antibody fragment such as an Fv fragment). A particularly preferred type of substitutional variant involves substituting one or more hypervariable region residues of a parent antibody. Generally, the resulting variant(s) selected for further development will have improved biological properties relative to the parent antibody from which they are generated. A convenient way for generating such substitutional variants is affinity maturation using phage display. Briefly, several hypervariable region sites (e.g. 6-7 sites) are mutated to generate all possible amino substitutions at each site. The antibody variants thus generated are displayed in a monovalent fashion from filamentous phage particles as fusions to the gene III product of M13 packaged within each particle. The phage-displayed variants are then screened for their biological activity (e.g. binding affinity) as herein disclosed. In order to identify candidate hypervariable region sites for modification, alanine scanning mutagenesis can be performed to identify hypervariable region residues contributing significantly to antigen bmdmg Alternatively, or m additionally, it may be beneficial to analyze a crystal structure of the antigen-antibody complex to identify contact points between the antibody and antigen Such contact residues and neighboring residues are candidates for substitution accordmg to the techniques elaborated herem Once such vaπants are generated, the panel of vaπants is subjected to screening as descπbed herein and antibodies with superior properties m one or more relevant assays may be selected for further development Another type of ammo acid vaπant of the antagonist alters the original glycosylation pattern of the antagonist By alteπng is meant deleting one or more carbohydrate moieties found in the antagonist, and/or adding one or more glycosylation sites that are not present m the antagonist Glycosylation of polypeptides is typically either N-linked or O-linked N- linked refers to the attachment of the carbohydrate moiety to the side chain of an asparagme residue The tπpeptide sequences asparagme-X-serme and asparagme-X-threonine, where X is any amino acid except prolme, are the recognition sequences for enzymatic attachment of the carbohydrate moiety to the asparagme side chain Thus, the presence of either of these tπpeptide sequences m a polypeptide creates a potential glycosylation site O- linked glycosylation refers to the attachment of one of the sugars N-aceylgalactosamine, galactose, or xylose to a hydroxyammo acid, most commonly serine or threonme, although 5-hydroxyprolme or 5-hydroxylysιne may also be used Addition of glycosylation sites to the antagonist is conveniently accomplished by altering the amino acid sequence such that it contams one or more of the above-descπbed tπpeptide sequences (for N-hnked glycosylation sites) The alteration may also be made by the addition of, or substitution by, one or more seπne or threonme residues to the sequence of the original antagonist (for O-linked glycosylation sites) Nucleic acid molecules encoding ammo acid sequence vaπants of the antagonist are prepared by a vaπety of methods known m the art These methods include, but are not limited to, isolation from a natural source (m the case of naturally occurring ammo acid sequence vaπants) or preparation by ohgonucleotide-mediated (or site- directed) mutagenesis, PCR mutagenesis, and cassette mutagenesis of an earlier prepared vanant or a non- vaπant version of the antagonist It may be desirable to modify the antagonist of the invention with respect to effector function, e g so as to enhance antigen-dependent cell-mediated cyotoxicity (ADCC) and or complement dependent cytotoxicity (CDC) of the antagonist This may be achieved by introducing one or more amino acid substitutions in an Fc region of an antibody antagonist Alternatively or additionally, cysteine resιdue(s) may be introduced in the Fc region, thereby allowing mterchain disulfide bond formation in this region The homodimeπc antibody thus generated may have improved internalization capability and/or increased complement-mediated cell killing and antibody-dependent cellular cytotoxicity (ADCC) See Caron et al , J Exp Med 176 1191-1195 (1992) and Shopes, B J Immunol 148 2918-2922 (1992) Homodimeπc antibodies with enhanced anti-tumor activity may also be prepared using heterobifunctional cross-lmkers as descπbed m Wolff etal Cancer Research 53 2560-2565 (1993) Alternatively, an antibody can be engineered which has dual Fc regions and may thereby have enhanced complement lysis and ADCC capabilities See Stevenson et al Anti-Cancer Drug Design 3 219-230 (1989) To increase the serum half life of the antagonist, one may incorporate a salvage receptor bmdmg epitope mto the antagonist (especially an antibody fragment) as described in US Patent 5,739,211, for example As used herein, the term "salvage receptor binding epitope" refers to an epitope of the Fc region of an IgG molecule (e , IgG ] , IgG 2 , IgG 3 , or IgG 4 ) that is responsible for increasing the in vivo serum half-life of the IgG molecule IV. Pharmaceutical Formulations Therapeutic formulations of the antagonists used in accordance with the present invention are prepared for storage by mixing an antagonist having the desired degree of purity with optional pharmaceutically acceptable carriers, excipients or stabilizers {Remington's Pharmaceutical Sciences 16th edition, Osol, A. Ed. (1980)), in the form of lyophilized formulations or aqueous solutions. Acceptable carriers, excipients, or stabilizers are nontoxic to recipients at the dosages and concentrations employed, and include buffers such as phosphate, citrate, and other organic acids; antioxidants including ascorbic acid and methionine; preservatives (such as octadecyldimethylbenzyl ammonium chloride; hexamethonium chloride; benzalkonium chloride, benzethonium chloride; phenol, butyl or benzyl alcohol; alkyl parabens such as methyl or propyl paraben; catechol; resorcinol; cyclohexanol; 3-pentanol; and m-cresol); low molecular weight (less than about 10 residues) polypeptides; proteins, such as serum albumin, gelatin, or immunoglobulins; hydrophilic polymers such as polyvinylpyrrolidone; amino acids such as glycine, glutamine, asparagine, histidine, arginine, or lysine; monosaccharides, disaccharides, and other carbohydrates including glucose, mannose, or dextrins; chelating agents such as EDTA; sugars such as sucrose, mannitol, trehalose or sorbitol; salt- forming counter-ions such as sodium; metal complexes (e.g. Zn-protein complexes); and/or non-ionic surfactants such as TWEEN™, PLURONICS™ or polyethylene glycol (PEG). Exemplary anti-CD20 antibody formulations are described in W098/56418, expressly incorporated herein by reference. This publication describes a liquid multidose formulation comprising 40 mg/mL rituximab, 25 mM acetate, 150 mM trehalose, 0.9% benzyl alcohol, 0.02% polysorbate 20 at pH 5.0 that has a minimum shelf life of two years storage at 2-8 °C. Another aηti-CD20 formulation of interest comprises 1 Omg/mL rituximab in 9.0 mg/mL sodium chloride, 7.35 mg/mL sodium citrate dihydrate, 0.7mg/mL polysorbate 80, and Sterile Water for Injection, pH 6.5. Lyophilized formulations adapted for subcutaneous administration are described in WO97/04801. Such lyophilized formulations may be reconstituted with a suitable diluent to a high protein concentration and the reconstituted formulation may be administered subcutaneously to the mammal to be treated herein. The formulation herein may also contain more than one active compound a., necessary for the particular indication being treated, preferably those with complementary activities that do not adversely affect each other. For example, it may be desirable to further provide a cytotoxic agent, chemotherapeutic agent, cytokine or immunosuppressive agent (e.g. one which acts on T cells, such as cyclosporin or an antibody that binds T cells, e.g. one which binds LFA-1). The effective amount of such other agents depends on the amount of antagonist present in the formulation, the type of disease or disorder or treatment, and other factors discussed above. These are generally used in the same dosages and with administration routes as used hereinbefore or about from 1 to 99% of the heretofore employed dosages. The active ingredients may also be entrapped in microcapsules prepared, for example, by coacervation techniques or by interfacial polymerization, for example, hydroxymethylcellulose or gelatin-microcapsules and poly - (methylmethacylate) microcapsules, respectively, in colloidal drug delivery systems (for example, liposomes, albumin microspheres, microemulsions, nano-particles and nanocapsules) or in macroemulsions. Such techniques are disclosed in Remington 's Pharmaceutical Sciences 16th edition, Osol, A. Ed. (1980). Sustained-release preparations may be prepared. Suitable examples of sustained-release preparations include semipermeable matrices of solid hydrophobic polymers containing the antagonist, which matrices are in the form of shaped articles, e.g. films, or microcapsules. Examples of sustained- release matrices include polyesters, hydrogels (for example, poly(2-hydroxyethyl-methacrylate), or poly(vinylalcohol)), polylactides (U.S. Pat. No. 3,773,919), copolymers of L-glutamic acid and γ ethyl-L-glutamate, non-degradable ethylene-vinyl acetate, degradable lactic acid-glycolic acid copolymers such as the LUPRON DEPOT™ (injectable microspheres composed of lactic acid- glycolic acid copolymer and leuprolide acetate), and poly-D-(-)-3-hydroxybutyric acid. The formulations to be used for in vivo administration must be sterile. This is readily accomplished by filtration through sterile filtration membranes. V. Treatment with the Antagonist The composition comprising an antagonist which binds to a B cell surface antigen will be formulated, dosed, and administered in a fashion consistent with good medical practice. Factors for consideration in this context include the particular disease or disorder being treated, the particular mammal being treated, the clinical condition of the individual patient, the cause of the disease or disorder, the site of delivery of the agent, the method of administration, the scheduling of administration, and other factors known to medical practitioners. The therapeutically effective amount of the antagonist to be administered will be governed by such considerations. As a general proposition, the therapeutically effective amount of the antagonist administered parenterally per dose will be in the range of about 0.1 to 20 mg/kg of patient body weight per day, with the typical initial range of antagonist used being in the range of about 2 to 10 mg/kg. The preferred antagonist is an antibody, e.g. an antibody such as RITUXAN®, which is not conjugated to a cytotoxic agent. Suitable dosages for an unconjugated antibody are, for example, in the range from about 20mg/m to about lOOOmg/m . In one embodiment, the dosage of the antibody differs from that presently recommended for RITUXAN®. For example, one may administer to the patient one or more doses of substantially less than 375mg/m of the antibody, e.g. where the dose is in the range from about 20mg/m 2 to about 250mg/m 2 , for example from about 2 n 50mg/m to about 200mg/m . Moreover, one may administer one or more initial dose(s) of the antibody followed by one or more 2 2 subsequent dose(s), wherein the mg/m dose of the antibody in the subsequent dose(s) exceeds the mg/m dose of 2 the antibody in the initial dose(s). For example, the initial dose may be in the range from about 20mg/m to about 250mg/m (e.g. from about 50mg/m to about 200mg/m ) and the subsequent dose may be in the range from about 2 2 250mg/m to about lOOOmg/m . As noted above, however, these suggested amounts of antagonist are subject to a great deal of therapeutic discretion. The key factor in selecting an appropriate dose and scheduling is the result obtained, as indicated above. For example, relatively higher doses may be needed initially for the treatment of ongoing and acute diseases. To obtain the most efficacious results, depending on the disease or disorder, the antagonist is administered as close to the first sign, diagnosis, appearance, or occurrence of the disease or disorder as possible or during remissions of the disease or disorder. The antagonist is administered by any suitable means, including parenteral, subcutaneous, intraperitoneal, intrapulmonary, and intranasal, and, if desired for local immunosuppressive treatment, intralesional administration. Parenteral infusions include intramuscular, intravenous, intraarterial, intraperitoneal, or subcutaneous administration. In addition, the antagonist may suitably be administered by pulse infusion, e.g., with declining doses of the antagonist. Preferably the dosing is given by injections, most preferably intravenous or subcutaneous injections, depending in part on whether the administration is brief or chronic. One may administer other compounds, such as cytotoxic agents, chemotherapeutic agents, immunosuppressive agents and/or cytokines with the antagonists herein The combmed administration includes coadmmistration, using separate formulations or a smgle pharmaceutical formulation, and consecutive administration m either order, wherein preferably there is a time period while both (or all) active agents simultaneously exert their biological activities Aside from administration of protein antagonists to the patient the present application contemplates administration of antagonists by gene therapy Such administration of nucleic acid encodmg the antagonist is encompassed by the expression "administering a therapeutically effective amount of an antagonist" See, for example, WO96/07321 published March 14, 1996 concerning the use of gene therapy to generate intracellular antibodies There are two major approaches to getting the nucleic acid (optionally contained in a vector) into the patient's cells, in vivo and ex vivo For in vivo delivery the nucleic acid is injected directly into the patient, usually at the site where the antagonist is required For ex vivo treatment, the patient's cells are removed, the nucleic acid is introduced into these isolated cells and the modified cells are administered to the patient either directly or, for example, encapsulated withm porous membranes which are implanted into the patient (see, e g U S Patent Nos 4,892,538 and 5,283,187) There are a vaπety of techniques available for introducing nucleic acids mto viable cells The techniques vary depending upon whether the nucleic acid is transferred into cultured cells in viti o, or in vivo m the cells of the intended host Techniques suitable for the transfer of nucleic acid into mammalian cells in vitro mclude the use of liposomes, electroporation, micromjection, cell fusion, DEAE-dextran, the calcium phosphate precipitation method, etc A commonly used vector for ex vivo delivery of the gene is a retrovirus The currently preferred in vivo nucleic acid transfer techniques include transfection with viral vectors (such as adenovirus, Herpes simplex I virus, or adeno-associated virus) and hpid-based systems (useful lipids for hpid- mediated transfer of the gene are DOTMA, DOPE and DC-Choi, for example) In some situations it is desirable to provide the nucleic acid source with an agent that targets the target cells, such as an antibody specific for a cell surface membrane protein or the target cell, a hgand for a receptor on the target cell, etc Where liposomes are employed, proteins which bind to a cell surface membrane protein associated with endocytosis may be used for targeting and or to facilitate uptake, e g capsid proteins or fragments thereof tropic for a particular cell type, antibodies for proteins which undergo lnternahzation in cycling, and proteins that target intracellular localization and enhance intracellular half-life The technique of receptor-mediated endocytosis is descπbed, for example, by Wu et al , J Biol Chem 262 4429-4432 (1987), and Wagner et al , Proc Natl Acad Sci USA 87 3410-3414 (1990) For review of the currently known gene marking and gene therapy protocols see Anderson et al , Science 256 808- 813 (1992) See also WO 93/25673 and the references cited therein VI. Articles of Manufacture In another embodiment of the invention, an article of manufacture containing materials useful for the treatment of the diseases or disorders described above is provided The article of manufacture comprises a contamer and a label or package insert on or associated with the container Suitable contamers include, for example, bottles, vials, syringes, etc The contamers may be formed from a vaπety of materials such as glass or plastic The container holds or contains a composition which is effective for treating the disease or disorder of choice and may have a sterile access port (for example the contamer may be an intravenous solution bag or a vial having a stopper pierceable by a hypodermic injection needle) At least one active agent in the composition is the antagonist which binds a B cell surface marker The label or package insert indicates that the composition is used for treatmg a patient having or predisposed to an autoimmune disease, such as those listed herem The article of manufacture may further comprise a second contamer comprising a pharmaceutically-acceptable diluent buffer, such as bacteriostatic water for injection (BWFI), phosphate-buffered salme, Ringer's solution and dextrose solution It may further mclude other materials desirable from a commercial and user standpoint, including other buffers, diluents, filters, needles, and syrmges Further details of the invention are illustrated by the following non-hmitmg Examples The disclosures of all citations in the specification are expressly incorporated herem by reference Example 1 Patients with clinical diagnosis of rheumatoid arthritis (RA) are treated with πtuximab (RITUXAN®) antibody The patient treated will not have a B cell malignancy Moreover, the patient is optionally further treated with any one or more agents employed for treatmg RA such as sahcylate, nonsteroidal anti-mflammatory drugs such as lndomethacin, phenylbutazone, phenylacetic acid denvatives (e g lbuprofen and fenoprofen), naphthalene acetic acids (naproxen), pyrrolealkanoic acid (tometm), indoleacetic acids (suhndac), halogenated anthrani c acid (meclofenamate sodium), piroxicam, zomepirac and diflunisal, antimalaπals such as chloroqume, gold salts, pemcillamme, or immunosuppressive agents such as methotrexate or corticosteroids in dosages known for such drugs or reduced dosages Preferably however, the patient is only treated with RITUXAN® RITUXAN® is admmistered intravenously (IV) to the RA patient accordmg to any of the following dosmg schedules (A) 50mg/m 2 IV day 1 150 mg/m 2 IV on days 8, 15 & 22 (B) 150mg/m 2 IV day l 375 mg/m 2 IV on days 8, 15 & 22 (C) 375 mg/m 2 IV days 1 , 8, 15 & 22 The primary response is determined by the Paulus index (Paulus et al Athritis Rheum 33 477-484 (1990)), i e improvement in morning stiffness, number of painful and inflamed joints, erythrocyte sedimentation (ESR), and at least a 2-poιnt improvement on a 5-poιnt scale of disease severity assessed by patient and by physician Administration of RITUXAN® will alleviate one or more of the symptoms of RA m the patient treated as descnbed above Example 2 Patients diagnosed with autoimmune hemolytic anemia (AIHA), e g , cryoglobinemia or Coombs positive anemia, are treated with RITUXAN® antibody AIHA is an acquired hemolytic anemia due to auto-antibodies that react with the patient's red blood cells The patient treated will not have a B cell malignancy RITUXAN® is admmistered intravenously (IV) to the patient according to any of the following dosmg schedules (A) 50mg/m 2 IV day 1 150 mg/m 2 IV on days 8, 15 & 22 (B) 150mg/m 2 IV day 1 375 mg/m 2 IV on days 8, 15 & 22 (C) 375 mg/m 2 IV days 1 , 8, 15 & 22 Further adjunct therapies (such as glucocorticoids, prednisone, azathioprine, cyclophosphamide, vinca-laden platelets or Danazol) may be combined with the RITUXAN® therapy, but preferably the patient is treated with RITUXAN® as a single-agent throughout the course of therapy. Overall response rate is determined based upon an improvement in blood counts, decreased requirement for transfusions, improved hemoglobin levels and or a decrease in the evidence of hemolysis as determined by standard chemical parameters. Administration of RITUXAN® will improve any one or more of the symptoms of hemolytic anemia in the patient treated as described above. For example, the patient treated as described above will show an increase in hemoglobin by at least 1 g/dl and an improvement in chemical parameters of hemolysis by 50% or return to normal as measured by serum lactic dehydrogenase, bilirubin. Example 3 Adult immune thrombocytopenic purpura (ITP) is a relatively rare hematologic disorder that constitutes the most common of the immune-mediated cytopenias. The disease typically presents with severe thrombocytopenia that may be associated with acute hemorrhage in the presence of normal to increased megakaryocytes in the bone marrow. Most patients with ITP have an IgG antibody directed against target antigens on the outer surface of the platelet membrane, resulting in platelet sequestration in the spleen and accelerated reticuloendothelial destruction of platelets (Bussell, J.B. Hematol. Oncol. Clin. North Am. (4): 179 ( 1990)). A number of therapeutic interventions have been shown to be effective in the treatment of ITP. Steroids are generally considered first-line therapy, after which most patients are candidates for intravenous immunoglobulin (IVIG), splenectomy, or other medical therapies including vincristine or immunosuppressive/cytotoxic agents. Up to 80% of patients with ITP initially respond to a course of steroids, but far fewer have complete and lasting remissions. Splenectomy has been recommended as standard second-line therapy for steroid failures, and leads to prolonged remission in nearly 60% of cases yet may result in reduced immunity to infection. Splenectomy is a major surgical procedure that may be associated with substantial morbidity (15%) and mortality (2%). IVIG has also been used as second line medical therapy, although only a small proportion of adult patients with ITP achieve remission. Therapeutic options that would interfere with the production of autoantibodi _s by activated B cells without the associated morbidities that occur with corticosteroids and/or splenectomy would provide an important treatment approach for a proportion of patients with ITP. Patients with clinical diagnosis of ITP (e.g. with a platelet count <50,000/μL) are treated with rituximab (RITUXAN®) antibody, optionally in combination with steroid therapy. The patient treated will not have a B cell malignancy. RITUXAN® is administered intravenously (IV) to the ITP patient according to any of the following dosing schedules: (A) 50mg/m 2 IV day 1 150 mg/m 2 IV on days 8, 15 & 22 (B) 150mg/m 2 IV day 1 375 mg/m 2 IV on days 8, 15 & 22 (C) 375 mg/m 2 IV days 1 , 8, 15 & 22 Patients are premedicated with one dose each of diphenhydramine 25-50 mg intravenously and acetaminophen 650 mg orally prior to the infusion of RITUXAN®. Using a sterile syringe and a 21 gauge or larger needle, the necessary amount of RITUXAN® is transferred from the vial into an IV bag containing sterile, pyrogen- free 0.9% Sodium Chloride, USP (saline solution). The final concentration of RITUXAN® is approximately 1 mg/mL. The initial dose infusion rate is initiated at 25 mg/hour for the first half hour then increased at 30 minute intervals by 50 mg/hr increments to a maximum rate of 200 mg/hours. If the first course of RITUXAN® is well tolerated, the infusion rates of subsequent courses start at 50 mg/hour and escalate at 30 minute intervals by 100 mg/hour increments to a maximum rate not to exceed 300 mg/hr. Vital signs (blood pressure, pulse, respiration, temperature) are monitored every 15 minutes x 4 or until stable, and then hourly until the infusion is completed. Overall response rate is determined based upon a platelet count determined on two consecutive occasions two weeks apart following the four weekly treatments of RITUXAN®. Patients treated with RITUXAN® will show improved platelet counts compared to patients treated with placebo. For example, in those patients with platelet count <20,000/μl, an increase in platelet count to >20,000/μl would be considered a response; and for those patients with platelet counts >20,000/μl and clinical evidence of bleeding, a total increase in platelet count by 10,000/μl or more and resolution of symptoms would be considered a response. See, George et al. "Idiopathic Thrombocytopenic Purpura: A Practice Guideline Developed by Explicit Methods for The American Society of Hematology" Blood 88:3-40 (1996), expressly incorporated herein by reference.

Claims: What is claimed is: 1. A method of treating an autoimmune disease in a mammal comprising administering to the mammal a therapeutically effective amount of an antagonist which binds to a B cell surface marker. 2. The method of claim 1 wherein the B cell surface marker is selected from the group consisting of CD10, CD19, CD20, CD21, CD22, CD23, CD24, CD37, CD53, CD72, CD73, CD74, CDw75, CDw76, CD77, CDw78, CD79a, CD79b, CD80, CD81, CD82, CD83, CDw84, CD85 and CD86. 3. The method of claim 1 wherein the antagonist comprises an antibody. 4. The method of claim 3 wherein the antibody binds CD20. 5. The method of claim 3 wherein the antibody binds CD19. 6. The method of claim 1 wherein the autoimmune disease is selected from the group consisting of psoriasis; dermatitis; systemic scleroderma and sclerosis; responses associated with inflammatory bowel disease; Crohn's disease; ulcerative colitis; respiratory distress syndrome; adult respiratory distress syndrome (ARDS); dermatitis; meningitis; encephalitis; uveitis; colitis; glomerulonephritis; allergic conditions; eczema ; asthma; conditions involving infiltration of T cells and chronic inflammatory responses; atherosclerosis; leukocyte adhesion deficiency; rheumatoid arthritis; systemic lupus erythematosus (SLE); diabetes mellitus; multiple sclerosis; Reynaud's syndrome; autoimmune thyroiditis; allergic encephalomyelitis; Sjorgen's syndrome; juvenile onset diabetes; immune responses associated with acute and delayed hypersensitivity mediated by cytokines and T-lymphocytes; tuberculosis; sarcoidosis; polymyositis; granulomatosis; vasculitis; pernicious anemia (Addison's disease); diseases involving leukocyte diapedesis; central nervous system (CNS) inflammatory disorder; multiple organ injury syndrome; hemolytic anemia; myasthenia gravis; antigen-antibody complex mediated diseases; anti-glomerular basement membrane disease; antiphospholipid syndrome; allergic neuritis; Graves' disease; Lambert-Eaton myasthenic syndrome; pemphigoid bullous; pemphigus; autoimmune polyendocrinopathies; Reiter's disease; stiff-man syndrome; Behcet disease; giant cell arteritis; immune complex nephritis; IgA nephropathy; IgM polyneuropathies; idiopathic thrombocytopenic purpura (ITP) and autoimmune thrombocytopenia. 7. The method of claim 1 wherein the mammal is human. 8. The method of claim 3 wherein the antibody is not conjugated with a cytotoxic agent. 9. The method of claim 4 wherein the antibody comprises rituximab (RITUXAN®). 10. The method of claim 3 wherein the antibody is conjugated with a cytotoxic agent. 11. The method of claim 10 wherein the cytotoxic agent is a radioactive compound. 12. The method of claim 11 wherein the antibody comprises Y2B8 or 131 I-B1 (BEXXAR™). 13. The method of claim 1 comprising administering the antagonist intravenously. 14. The method of claim 1 comprising administering the antagonist subcutaneously. 15. The method of claim 3 comprising administering a dose of substantially less than 375mg/m of the antibody to the mammal. 16. The method of claim 15 wherein the dose is in the range from about 20mg/m~ to about 250mg/m . 17. The method of claim 16 wherein the dose is in the range from about 50mg/m ~ to about 200mg/m . 18. The method of claim 3 comprising administering an initial dose of the antibody followed by a subsequent 2 2 dose, wherein the mg/m dose of the antibody in the subsequent dose exceeds the mg/m dose of the antibody in the initial dose. 19. The method of claim 6 wherein the autoimmune disease is immune thrombocytopenic purpura (ITP). 20. The method of claim 6 wherein the autoimmune disease is rheumatoid arthritis. 21. The method of claim 6 wherein the autoimmune disease is hemolytic anemia. 22. The method of claim 21 wherein the hemolytic anemia is cryoglobinemia or Coombs positive anemia. 23. The method of claim 6 wherein the autoimmune disease is vasculitis. 24. The method of claim 1 which consists essentially of administering the antagonist to the mammal. 25. An article of manufacture comprising a container and a composition contained therein, wherein the composition comprises an antagonist which binds to a B cell surface marker, and further comprising a package insert instructing the user of the composition to treat a patient having or predisposed to an autoimmune disease. 26. The article of manufacture of claim 25 wherein the autoimmune disease is selected from the group consisting of psoriasis; dermatitis; systemic scleroderma and sclerosis; responses associated with inflammatory bowel disease; Crohn's disease; ulcerative colitis; respiratory distress syndrome; adult respiratory distress syndrome (ARDS); dermatitis; meningitis; encephalitis; uveitis; colitis; glomerulonephritis; allergic conditions; eczema; asthma; conditions involving infiltration of T cells and chronic inflammatory responses; atherosclerosis; leukocyte adhesion deficiency; rheumatoid arthritis; systemic lupus erythematosus (SLE); diabetes mellitus; multiple sclerosis; Reynaud's syndrome; autoimmune thyroiditis; allergic encephalomyelitis; Sjorgen's syndrome; juvenile onset diabetes; immune responses associated with acute and delayed hypersensitivity mediated by cytokines and T- lymphocytes; tuberculosis; sarcoidosis; polymyositis; granulomatosis; vasculitis; pernicious anemia (Addison's disease); diseases involving leukocyte diapedesis; central nervous system (CNS) inflammatory disorder; multiple organ injury syndrome; hemolytic anemia; myasthenia gravis; antigen-antibody complex mediated diseases; anti-glomerular basement membrane disease; antiphospholipid syndrome; allergic neuritis; Graves ' disease; Lambert-Eaton myasthenic syndrome; pemphigoidbullous; pemphigus; autoimmune polyendocrinopathies; Reiter's disease; stiff-man syndrome; Behcet disease; giant cell arteritis; immune complex nephritis; IgA nephropathy; IgM polyneuropathies; idiopathic thrombocytopenic purpura (ITP) and autoimmune thrombocytopenia.

Inventors: CURD JOHN G, GRILLO-LOPEZ ANTONIO J, KUNKEL LORI A, CURD, JOHN, G., GRILLO-LOPEZ, ANTONIO, J., KUNKEL, LORI, A.
Applicants: GENENTECH INC, IDEC PHARMACEUTICALS INC, GENENTECH, INC., IDEC PHARMACEUTICALS, INC.
Application year: 2000
Main classification: A61K39
IPC codes: A61K39, A61K45, A61K47, A61K51, A61P1, A61P3, A61P7, A61P9, A61P11, A61P13, A61P17, A61P19, A61P21, A61P25, A61P29, A61P31, A61P35, A61P37, C07K16