bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rapid and Long-Term Disappearance of CD4+ T Lymphocyte Responses Specific for Anaplasma Marginale Major Surface Protein-2 (MSP2) in MSP2 Vaccinates following Challenge with Live A. marginale
Authors: Abbott Jeffrey R. , Palmer Guy H. , Kegerreis Kimberly A. , Hetrick Peter F. , Howard Chris J. , Hope Jayne C. , Brown Wendy C. 
Published: April 2014

Abstract
In humans and ruminants infected with Anaplasma, the major surface protein 2 (MSP2) is immunodominant. Numerous CD4+ T cell epitopes in the hypervariable and conserved regions of MSP2 contribute to this immunodominance. Antigenic variation in MSP2 occurs throughout acute and persistent infection, and sequentially emerging variants are thought to be controlled by variant-specific Ab. This study tested the hypothesis that challenge of cattle with Anaplasma marginale expressing MSP2 variants to which the animals had been immunized, would stimulate variant epitope-specific recall CD4+ T cell and IgG responses and organism clearance. MSP2-specific T lymphocyte responses, determined by IFN-γ ELISPOT and proliferation assays, were strong before and for 3 wk postchallenge. Surprisingly, these responses became undetectable by the peak of rickettsemia, composed predominantly of organisms expressing the same MSP2 variants used for immunization. Immune responsiveness remained insignificant during subsequent persistent A. marginale infection up to 1 year. The suppressed response was specific for A. marginale, as responses to Clostridium vaccine Ag were consistently observed. CD4+CD25+ T cells and cytokines IL-10 and TGF-β1 did not increase after challenge. Furthermore, a suppressive effect of nonresponding cells was not observed. Lymphocyte proliferation and viability were lost in vitro in the presence of physiologically relevant numbers of A. marginale organisms. These results suggest that loss of memory T cell responses following A. marginale infection is due to a mechanism other than induction of T regulatory cells, such as peripheral deletion of MSP2-specific T cells.
Selective Expression of the Cre Recombinase in Late-Stage Thymocytes Using the Distal Promoter of the Lck Gene
Authors: Zhang Dong Ji , Wang Qi , Wei Jie , Baimukanova Gyulnar , Buchholz Frank , Stewart A. Francis , Mao Xiaohong , Killeen Nigel 
Published: April 2014

Abstract
Transgenic mouse lines were generated that express the Cre recombinase under the control of the distal promoter of the mouse Lck gene. Cre recombination in four of these lines of transgenic mice was characterized at the single cell level using ROSA26-regulated loxP-Stop-loxP-βgeo and loxP-Stop-loxP-YFP reporter mouse lines. Two of the lines showed T cell-restricted Cre recombination, whereas the other two also expressed Cre in B cells, NK cells, and monocytes. Cre recombination began at a late stage of T cell development (at or after up-regulation of the TCR during positive selection) in the two T cell-restricted lines. Lines of mice that express the Cre recombinase at late stages of thymocyte development are of value for determining the impact of mutations on T cell function in the absence of complicating effects on early thymocyte selection.
Impairment of Thymocyte Development by Dominant-Negative Kuzbanian (ADAM-10) Is Rescued by the Notch Ligand, Delta-1
Authors: Manilay Jennifer O. , Anderson Ana C. , Kang Chulho , Robey Ellen A. 
Published: April 2014

Abstract
Although Notch plays a crucial role in T cell development, regulation of Notch signaling in the thymus is not well understood. Kuzbanian, an ADAM protease, has been implicated in the cleavage of both Notch receptors and the Notch ligand, Delta. In this study we show that the expression of a dominant-negative form of Kuzbanian (dnKuz) leads to reduced TCRβ expression in double-negative thymocytes and to a partial block between the double-negative to double-positive stages of development. These defects were rescued by overexpression of Delta-1 on thymocytes. Mixed chimeras showed a cell-autonomous block by dnKuz, but non-cell-autonomous rescue by Delta-1. This suggests that dnKuz impairs Notch signaling in receiving cells, and increasing Delta-1 on sending cells overcomes this defect. Interestingly, the expression of an activated form of Notch-1 rescued some, but not all, the defects in dnKuz Tg mice. Our data suggest that multiple Notch-dependent steps in early thymocyte development require Kuzbanian, but differ in the involvement of other Notch signaling components.
Enhanced CD4 T Cell Responsiveness in the Absence of 4-1BB
Authors: Lee Seung-Woo , Vella Anthony T. , Kwon Byoung S. , Croft Michael 
Published: April 2014

Abstract
The 4-1BB (CD137) is a member of the TNFR superfamily, and is expressed on several cell types, including activated T cells. Although 4-1BB ligation by agonistic Ab or 4-1BB ligand-expressing APCs can costimulate T cells, the physiological significance of 4-1BB expression in vivo during T cell responses is still being elucidated. In this study, we have addressed the impact on CD4 T cell priming when 4-1BB is absent after gene targeting. Surprisingly, 4-1BB−/− mice generated more enhanced effector CD4 T cell responses to OVA protein in adjuvant, even though Ab responses in 4-1BB−/− mice were normal. Using an adoptive transfer system with OT-II TCR transgenic CD4 T cells, we found that 4-1BB−/− CD4 cells responding in a 4-1BB-sufficient environment had enhanced cell division compared with wild-type cells and displayed augmented clonal expansion during the primary response. This was not due to a developmental defect as 4-1BB-deficient CD4 cells could respond normally to Ag in vitro. These results demonstrate that the absence of 4-1BB can make CD4 T cells hyperresponsive to protein Ag in vivo, suggesting a new unappreciated negative regulatory role of 4-1BB when expressed on a T cell.
Leptin Promotes Differentiation and Survival of Human Dendritic Cells and Licenses Them for Th1 Priming
Authors: Mattioli Benedetta , Straface Elisabetta , Quaranta Maria Giovanna , Giordani Luciana , Viora Marina 
Published: April 2014

Abstract
Leptin is an adipocyte-derived hormone/cytokine that links nutrition, metabolism, and immune homeostasis. Leptin is capable of modulating several immune responses. However, the effect of leptin on dendritic cells (DCs) has not yet been recognized. Because DCs are instrumental in the development of immune responses, in this study, we evaluated the impact of leptin on DC activation. We demonstrated the presence of leptin receptor in human immature and mature DCs both at mRNA and protein level and its capacity to transduce leptin signaling leading to STAT-3 phosphorylation. We found no consistent modulation of DC surface molecules known to be critical for their APC function in response to leptin. In contrast, we found that leptin induces rearrangement of actin microfilaments, leading to uropod and ruffle formation. At a functional level, leptin up-regulates the IL-1β, IL-6, IL-12, TNF-α, and MIP-1α production. Coincident with this, leptin-treated DCs stimulate stronger heterologous T cell responses. Furthermore, we found that leptin down-regulates IL-10 production by DCs and drives naive T cell polarization toward Th1 phenotype. Finally, we found that leptin partly protects DCs from spontaneous and UVB-induced apoptosis. Consistent with the antiapoptotic effect of leptin, we observed the activation of NF-κB and a parallel up-regulation of bcl-2 and bcl-xL gene expression. These results provide new insights on the immunoregulatory function of leptin demonstrating its ability to improve DC functions and to promote DC survival. This is of relevance considering a potential application of leptin in immunotherapeutic approaches and its possible use as adjuvant in vaccination protocols.
Impaired Transporter Associated with Antigen Processing-Dependent Peptide Transport during Productive EBV Infection
Authors: Ressing Maaike E. , Keating Sinéad E. , van Leeuwen Daphne , Koppers-Lalic Danijela , Pappworth Isabel Y. , Wiertz Emmanuel J. H. J. , Rowe Martin 
Published: April 2014

AbstractHuman herpesviruses, including EBV, persist for life in infected individuals. During the lytic replicative cycle that is required for the production of infectious virus and transmission to another host, many viral Ags are expressed. Especially at this stage, immune evasion strategies are likely to be advantageous to avoid elimination of virus-producing cells. However, little is known about immune escape during productive EBV infection because no fully permissive infection model is available. In this study, we have developed a novel strategy to isolate populations of cells in an EBV lytic cycle based on the expression of a reporter gene under the control of an EBV early lytic cycle promoter. Thus, induction of the viral lytic cycle in transfected EBV+ B lymphoma cells resulted in concomitant reporter expression, allowing us, for the first time, to isolate highly purified cell populations in lytic cycle for biochemical and functional studies. Compared with latently infected B cells, cells supporting EBV lytic cycle displayed down-regulation of surface HLA class I, class II, and CD20, whereas expression levels of other surface markers remained unaffected. Moreover, during lytic cycle peptide transport into the endoplasmic reticulum, was reduced to &lt;30% of levels found in latent infection. Because steady-state levels of TAP proteins were unaffected, these results point toward EBV-induced interference with TAP function as a specific mechanism contributing to the reduced levels of cell surface HLA class I. Our data implicate that EBV lytic cycle genes encode functions to evade T cell recognition, thereby creating a window for the generation of viral progeny.
A Mutant Cell with a Novel Defect in MHC Class I Quality Control
Authors: York Ian A. , Grant Ethan P. , Dahl A. Maria , Rock Kenneth L. 
Published: April 2014

Abstract
COS7 (African Green Monkey kidney) cells stably transfected with the mouse MHC class I allele H-2Kb were mutagenized, selected for low surface expression of endogenous MHC class I products, and subcloned. A mutant cell line, 4S8.12, expressing very low surface MHC class I (∼5% of parental levels) was identified. This cell line synthesized normal levels of the MHC class I H chain and β2-microglobulin, as well as normal levels of TAP, tapasin, GRP78, calnexin, calreticulin, ERp57, and protein disulfide isomerase. Full-length OVA was processed to generate presented H-2Kb-SIINFEKL complexes with equal efficiency in wild-type and mutant cells, demonstrating that proteasomes, as well as TAP and tapasin, functioned normally. Therefore, all the known components of the MHC class I Ag presentation pathway were intact. Nevertheless, primate (human and monkey) MHC class I H chain and β2-microglobulin failed to associate to form the normal peptide-receptive complex. In contrast, mouse H chains associated with β2-microglobulin normally and bound peptide at least as well as in wild-type cells. The 4S8.12 cells provide strong genetic evidence for a novel component in the MHC class I pathway. This as-yet unidentified gene is important in early assembly of primate, but not mouse, MHC class I complexes.
In Situ Sensory Adaptation of Tumor-Infiltrating T Lymphocytes to Peptide-MHC Levels Elicits Strong Antitumor Reactivity
Authors: Dorothée Guillaume , Vergnon Isabelle , El Hage Faten , Chansac Béatrice Le Maux , Ferrand Vincent , Lécluse Yann , Opolon Paule , Chouaib Salem , Bismuth Georges , Mami-Chouaib Fathia 
Published: April 2014

Abstract
We have isolated from tumor-infiltrating lymphocytes (TIL) and PBL of a lung carcinoma patient several tumor-specific T cell clones displaying similar peptide-MHC tetramer staining and expressing a unique TCR. Although these clones elicited identical functional avidity and similar cytolytic potential, only T cell clones derived from TIL efficiently lysed autologous tumor cells. Interestingly, all of these clones expressed the same T cell surface markers except for the TCR inhibitory molecule CD5, which was expressed at much lower levels in TIL than in PBL. Video-imaging recordings demonstrated that, although both T cell clones could form stable conjugates with tumor cells, the Ca2+ response occurred in TIL clones only. Significantly, analysis of a panel of circulating clones indicated that antitumor cytolytic activity was inversely proportional to CD5 expression levels. Importantly, CD5 levels in TIL appeared to parallel the signaling intensity of the TCR/peptide-MHC interaction. Thus, in situ regulation of CD5 expression may be a strategy used by CTL to adapt their sensitivity to intratumoral peptide-MHC levels.
CD4 T Cell-Dependent Conditioning of Dendritic Cells to Produce IL-12 Results in CD8-Mediated Graft Rejection and Avoidance of Tolerance
Authors: Filatenkov Alexander A. , Jacovetty Erica L. , Fischer Ursula B. , Curtsinger Julie M. , Mescher Matthew F. , Ingulli Elizabeth 
Published: April 2014

Abstract
Rejection of ectopic heart transplants expressing OVA requires OVA-specific CD4 and CD8 T cells. In the absence of CD4 T cells, OVA-specific CD8 T cells proliferate and migrate to the graft, but fail to develop cytolytic functions. With CD4 T cells present, clonal expansion of the CD8 T cells is only marginally increased but the cells now develop effector functions and mediate rapid graft rejection. In the presence of CD4 T cells, Ag and B7 levels do not increase on dendritic cells but IL-12 production is up-regulated, and this requires CD154 expression on the CD4 T cells. OVA-specific CD8 T cells lacking the IL-12 receptor fail to differentiate or mediate graft rejection even when CD4 T cells are present. Thus, CD4 T cells condition dendritic cells by inducing the production of IL-12, which is needed as the “third signal” for CD8 T cell differentiation and avoidance of tolerance.
B Cells from Mice Prematurely Expressing Human Complement Receptor Type 2 Are Unresponsive to T-Dependent Antigens
Authors: Birrell Louise , Kulik Liudmila , Morgan B. Paul , Holers V. Michael , Marchbank Kevin J. 
Published: April 2014

AbstractComplement receptor type 2 (CR2/CD21), in association with CD19, plays an important role in enhancing mature B cell responses to opsonized Ags. We have shown that mice expressing a human CR2/CD21 (hCR2/CD21) transgene during the CD43+/CD25− late pro-B cell stage of B cell development demonstrate marked changes in subsequent B cell ontogeny. In the present study, we show that the humoral immune response to the T cell-dependent Ag, sheep RBC, is muted severely in a manner inversely proportional to B cell expression level of hCR2. Individual Ag-specific IgG isotypes vary in the degree to which they are affected but all are reduced while IgM titers are normal. A substantial reduction in germinal centers, both in size and frequency, in the spleens of immunized hCR2 transgenic mice demonstrates a failure to maintain germinal center reaction. However, both IgM expression levels and LPS-proliferative responses appear fully intact in B cells from hCR2-positive mice, suggesting that this alteration in B cell phenotype is different qualitatively from that of specific Ag-defined anergy models. These data suggest that the unresponsiveness to T-dependent Ags displayed by hCR2-positive B cells is linked to an increase in the level of stimulus required to propel the B cell into a fully activated state and thus a normal humoral immune response to Ags. We conclude that this phenotype and these mice may offer an additional means to dissect mechanisms underlying B cell tolerance and Ag responsiveness both in bone marrow and periphery.
Cathepsin-L Influences the Expression of Extracellular Matrix in Lymphoid Organs and Plays a Role in the Regulation of Thymic Output and of Peripheral T Cell Number
Authors: Lombardi Gabriela , Burzyn Dalia , Mundiñano Juliana , Berguer Paula , Bekinschtein Pedro , Costa Hector , Castillo Lilian Fedra , Goldman Alejandra , Meiss Roberto , Piazzon Isabel , Nepomnaschy Irene 
Published: April 2014

Abstract
Nackt mice, which are deficient in cathepsin-L (CTSL), show an early impairment during positive selection in the context of class II MHC molecules and as a consequence, the percentage and absolute number of CD4+ thymocytes are significantly decreased. In this study, we show that lymph nodes from nackt mice are hypertrophied, showing normal absolute numbers of CD4+ T cells and marked increases in the number of CD8+ T lymphocytes. Basal proliferative levels are increased in the CD4+ but not in the CD8+ population. Lymph node T cells show increases in the expression of α5, α6, and β1 integrin chains. These alterations correlate with increases in the expression of extracellular matrix (ECM) components in lymph nodes. Interestingly, laminin, fibronectin, and collagen I and IV are markedly decreased in nackt thymus which shows an augmented output of CD8+ cells. These results demonstrate that a mutation in the Ctsl gene influences the levels of ECM components in lymphoid organs, the thymic output, and the number of T cells in the periphery. They further raise the possibility that, by regulating the level of expression of ECM components in lymphoid organs, CTSL is able to broadly affect the immune system.
CD229 (Ly9) Lymphocyte Cell Surface Receptor Interacts Homophilically through Its N-Terminal Domain and Relocalizes to the Immunological Synapse
Authors: Romero Xavier , Zapater Nuria , Calvo María , Kalko Susana G. , de la Fuente Miguel Angel , Tovar Victoria , Ockeloen Charlotte , Pizcueta Pilar , Engel Pablo 
Published: April 2014

Abstract
CD229 is a member of the CD150 family of the Ig superfamily expressed on T and B cells. Receptors of this family regulate cytokine production and cytotoxicity of lymphocytes and NK cells. The cytoplasmic tail of CD229 binds to SAP, a protein that is defective in X-linked lymphoproliferative syndrome. To identify the CD229 ligand, we generated a soluble Ig fusion protein containing the two N-terminal extracellular domains of human CD229 (CD229-Ig). CD229-Ig bound to CD229-transfected cells, whereas no binding was detected on cells expressing other CD150 family receptors, showing that CD229 binds homophilically. Both human and mouse CD229 interacted with itself. Domain deletion mutants showed that the N-terminal Ig-domain mediates homophilic adhesion. CD229-CD229 binding was severely compromised when the charged amino acids E27 and E29 on the predicted B-C loop and R89 on the F-G loop of the N-terminal domain were mutated to alanine. In contrast, one mutation, R44A, enhanced the homophilic interaction. Confocal microscopy image analysis revealed relocalization of CD229 to the contact area of T and B cells during Ag-dependent immune synapse formation. Thus, CD229 is its own ligand and participates in the immunological synapse.
The Radioprotective 105/MD-1 Complex Links TLR2 and TLR4/MD-2 in Antibody Response to Microbial Membranes
Authors: Nagai Yoshinori , Kobayashi Toshihiko , Motoi Yuji , Ishiguro Kohtaroh , Akashi Sachiko , Saitoh Shin-ichiroh , Kusumoto Yutaka , Kaisho Tsuneyasu , Akira Shizuo , Matsumoto Mitsuru , Takatsu Kiyoshi , Miyake Kensuke 
Published: April 2014

Abstract
Low-affinity IgG3 Abs to microbial membranes are important for primary immune defense against microbes, but little is known about the importance of TLRs in their production. IgG3 levels were extremely low in mice lacking radioprotective 105 (RP105), a B cell surface molecule structurally related to TLRs. RP105−/− B cells proliferated poorly in response to not only the TLR4 ligand LPS but also TLR2 ligand lipoproteins, both of which mediate the immunostimulatory activity of microbial membranes. RP105−/− mice were severely impaired in hapten-specific Ab production against LPS or lipoproteins. CD138 (syndecan-1)-positive plasma cells were detected after lipid A injection in wild-type spleen but much less in RP105−/− spleen. RP105 ligation in vivo induced plasma cell differentiation. RP105 expression was ∼3-fold higher on marginal zone B cells than on follicular and B1 cells and was down-regulated on germinal center cells. These results demonstrate that a signal via RP105 is uniquely important for regulating TLR-dependent Ab production to microbial membranes.
Dendritic Cell Maturation Induced by Muramyl Dipeptide (MDP) Derivatives: Monoacylated MDP Confers TLR2/TLR4 Activation
Authors: Uehori Junji , Fukase Koichi , Akazawa Takashi , Uematsu Satoshi , Akira Shizuo , Funami Kenji , Shingai Masashi , Matsumoto Misako , Azuma Ichiro , Toyoshima Kumao , Kusumoto Shoichi , Seya Tsukasa 
Published: April 2014

Abstract
6-O-acyl-muramyldipeptides (MDP) with various lengths of fatty acid chains were examined for their dendritic cell (DC) maturation activity expressed through TLRs. Judging from anti-TLR mAb/inhibitor-blocking analysis, MDP derivatives with a single octanoyl or stearoyl fatty acid chain were found to activate TLR2 and TLR4 on human DCs, although intact and diacylated MDP expressed no ability to activate TLRs. Human DC activation profiles by the monoacylated MDP were essentially similar to those by Calmette-Guérin (BCG)-cell wall skeleton (CWS) and BCG-peptidoglycan (PGN) based on their ability to up-regulate costimulators, HLA-DR, β2-microglobulin, and allostimulatory MLR. Monoacylated MDP induced cytokines with similar profiles to BCG-CWS or -PGN, although their potency for induction of TNF-α, IL-12p40, and IL-6 was less than that of BCG-CWS or -PGN. The MDP derivatives initiated similar activation in normal mouse macrophages, but exhibited no effect on TLR2/4-deficient or MyD88-deficient mouse macrophages. Mutation of d-isoGln to l-isoGln in monoacylated MDP did not result in loss of the DC maturation activity, suggesting marginal participation of nucleotide-binding oligomerization domain 2, if any, in monoacyl MDP-dependent DC maturation. These results define the adjuvant activity of 6-O-acyl MDP compounds at the molecular level. They target TLR2/TLR4 and act through the MyD88-dependent pathway in DCs and macrophages. Hence, the unusual combined activation of TLR2 and TLR4 observed with Mycobacterium tuberculosis is in part reflected in the functional properties of monoacylated MDP compounds. These findings infer that the essential minimal requirement for TLR2/4-mediated adjuvancy of BCG lies within a modified MDP.
Differential Immunogenicity of Two Peptides Isolated by High Molecular Weight-Melanoma-Associated Antigen-Specific Monoclonal Antibodies with Different Affinities
Authors: Luo Wei , Hsu Jeff Chi-feng , Tsao Chun-Yen , Ko Eric , Wang Xinhui , Ferrone Soldano 
Published: April 2014

Abstract
Peptide mimics isolated from phage display peptide libraries by panning with self-tumor-associated Ag (TAA)-specific mAbs are being evaluated as immunogens to implement active specific immunotherapy. Although TAA-specific mAb are commonly used to isolate peptide mimics, no information is available regarding the Ab characteristics required to isolate immunogenic TAA peptide mimics. To address this question, we have used mAb 763.74 and mAb GH786, which recognize the same or spatially close antigenic determinant(s) of the human high m.w.-melanoma-associated Ag (HMW-MAA), although with different affinity. mAb 763.74 affinity is higher than that of mAb GH786. Panning of phage display peptide libraries with mAb 763.74 and mAb GH786 resulted in the isolation of peptides P763.74 and PGH786, respectively. When compared for their ability to induce HMW-MAA-specific immune responses in BALB/c mice, HMW-MAA-specific Ab titers were significantly higher in mice immunized with P763.74 than in those immunized with PGH786. The HMW-MAA-specific Ab titers were markedly increased by a booster with HMW-MAA-bearing melanoma cells, an effect that was significantly higher in mice primed with P763.74 than in those primed with PGH786. Lastly, P763.74, but not PGH786, induced a delayed-type hypersensitivity response to HMW-MAA-bearing melanoma cells. These findings suggest that affinity for TAA is a variable to take into account when selecting mAb to isolate peptide mimics from a phage display peptide library.