bluuebunny/crossref_metadata_2025_split huggingface dataset:
Activation of the gp130 signaling pathway by monoclonal antibodies directed against the gp130 molecule
Authors: Autissier Patrick , Liautard Janny , Brochier Jean , Gaillard Jean Philippe 
Published: March 2007

AbstractSix cytokines of the interleukin (IL)‐6 family involved in various inflammatory or tumoral diseases share the same gp130 signal transducer chain. We made a panel of anti‐gp130 monoclonal antibodies (mAb) to study the structure and function of the gp130 molecule. These mAb recognized different epitopes of the gp130 that we called A to J. Most of the mAb were found to be inhibitors and we studied whether some of them could also induce gp130 activation. When used alone, none of them was able to initiate the proliferation of IL‐6‐dependent cell lines. However, some particular associations of the mAb were able to induce a proliferative response. mAb B1 could activate the lines in association with F1 or with I2 but not with I1, which in ELISA was similar to I2. In contrast mAb B2, which in ELISA appeared to be very similar to B1, was able to activate the cells in association with I1 but not with F1 or I2. Two other mAb belonging to specificities A and C were found to be activators either in association with I1 only, or with I1 or B2, respectively. These associations of mAb appeared to be nearly as potent activators as IL‐6 itself. Although we still have no precise idea of the mechanisms involved, they are interesting tools to study the molecular interactions leading to gp130 activation and, from a practical point of view, valuable growth factors of hematopoietic stem cells.
Selectivity of the major histocompatibility complex class II presentation pathway of cortical thymic epithelial cell lines
Authors: Oukka Mohamed , Andre Patrice , Tunnel Pascale , Besnard Nelly , Angevin Veronique , Karlsson Lars , Trans Phuong L. , Charron Dominique , Bihain Bernard , Kosmatopoulos Kostadinos , Lotteau Vincent 
Published: March 2007

AbstractMajor histocompatibility complex (MHC) restriction of the immune response is established during positive selection of T cells in the thymus. This occurs mainly through interactions of T cell receptor of developing thymocytes with MHC/peptide ligands on cortical thymic epithelial cells (TEC). An ongoing controversy concerns the origin and the role of peptides involved in the positive selection of thymocytes. Evidence provided here shows that processing of MHC class II complexes in cortical TEC differs from that of medullary TEC. Removal of the invariant chain associated with MHC class II complexes was rapid and complete in medullary TEC which present peptides from both exogenous and cytosolic origin. In cortical TEC, a large fraction of class II dimers remained associated with a 10–12‐kDa fragment of invariant chain (Ii). Incomplete removal of Ii correlated with the inability of cortical TEC to present peptides from exogenous origin. However, presentation of peptides from cytosolic proteins by cortical TEC remained possible. Thus, most peptides from exogenous proteins may be excluded from participating in positive selection of CD4+ T cells by a mechanism limiting Ii breakdown.
The rational design of TAP inhibitors using peptide substrate modifications and peptidomimetics
Authors: Grommé Monique , van der Valk Richard , Sliedregt Karen , Vernie Leen , Liskamp Rob , Hämmerling Günter , Koopmann Jens‐Oliver , Momburg Frank , Neefjes Jacques 
Published: March 2007

AbstractThe major histocompatibility complex (MHC)‐encoded transporter associated with antigen processing (TAP) translocates peptides from the cytosol into the lumen of the endoplasmic reticulum. This step precedes the binding of peptides to MHC class I molecules and is essential for cell surface expression of the MHC class I/peptide complex. TAP has a broad sequence specificity and a preference for peptides of around 9 amino acids. To synthesize inhibitors for TAP, we studied various alterations of the peptide substrate. The results indicate that TAP is stereospecific and that peptide bonds engineered into isosteric structures can improve translocation of the peptide. Furthermore, TAP is able to translocate peptides with large side chains that correspond to a peptide of ∼ 21 amino acids in extended conformation. Peptides with longer side chains compete for the peptide binding site of TAP but fail to be translocated. Therefore, they represent the first rationally designed inhibitors of TAP.
A novel 4‐kb interleukin‐13 receptor α mRNA expressed in human B, T, and endothelial cells encoding an alternate type‐II interleukin‐4/ interleukin‐13 receptor
Authors: Gauchat Jean‐François , Schlagenhauf Edith , Feng Ning‐Ping , Moser René , Yamage Mat , Jeannin Pascale , Alouani Sami , Elson Greg , Notarangelo Luigi D. , Wells Timothy , Eugster Hans‐Pietro , Bonnefoy Jean‐Yves 
Published: March 2007

AbstractA 4 kb human interleukin‐13 receptor (IL‐13R) chain cDNA was cloned from a B cell cDNA library using expressed sequence tags homologous to mouse IL‐13R as probes. The deduced protein sequence shows a significant level of sequence identity with the IL‐5R and the human IL‐13R identified recently by expression cloning. The cytoplasmic region is very highly conserved between human and mouse homologs and contains a consensus binding motif for a signal transducer and activator of transcription. The cDNA encodes a protein binding IL‐13 when expressed alone which participates in a receptor complex for both IL‐4 and IL‐13 when expressed in conjunction with the IL‐4Rα chain. Transcripts for this IL‐13R chain could be detected in most tissues and organs studied and in T, B, endothelial cells, basophilic, immature mast cell, and monocytic cell lines. The pattern of expression is different from the other recently cloned IL‐13R molecule, and correlates with sites where IL‐4 and IL‐13 signaling is known to occur. This novel receptor is therefore likely to be implicated in reactions involved in IgE responses, T helper 2 differentiation, adhesion of leukocytes to endothelium, and therefore in pathological phenomena such as allergy, atopy, and asthma.
Presentation of abundant endogenous class II DR‐restricted antigens by DM‐negative B cell lines
Authors: Kovats Susan , Whiteley Phyllis E. , Concannon Patrick , Rudensky Alexander Y. , Blum Janice S. 
Published: March 2007

AbstractPeptides derived from endogenous and exogenous antigens compete for binding and presentation via class II molecules. Studies with mutant B cell lines defective in exogenous antigen presentation suggest that HLA‐DM molecules facilitate the interaction of foreign peptides and class II molecules. In contrast, presentation of self antigens is not strictly dependent upon HLA‐DM, as demonstrated by the ability of these mutant cells to activate T cells specific for endogenous antigens. Two distinct classes of DM‐negative cells, T2 cells generated by in vitro mutagenesis and lines derived from bare lymphocyte syndrome (BLS) patients, were able to present epitopes derived from self proteins. Transfection of DM genes into the mutant cells enhanced the presentation of some, but not all, endogenous antigens, suggesting that formation of select endogenous peptide/class II complexes is not dependent upon DM. The efficiency of endogenous antigen presentation in the absence of DM was also dependent on the mutant antigen‐presenting cell studied, as the TxB hybrid T2 presented greater amounts of self peptides compared to cells from BLS patients. Thus, additional genes, aside from DM, may regulate the pathway for endogenous antigen presentation.
T cells recognize the VH complementarity‐determining region 3 of the idiotypic protein of B cell non‐Hodgkin's lymphoma
Authors: Wen Yue‐Jin , Lim Seah H. 
Published: March 2007

AbstractThe idiotypic protein expressed by B lymphoma cells is a clone‐specific tumor antigen which may be suitable for immune targeting by T cells. In this study, we cloned the immunoglobulin heavy chain variable gene (VH) of the idiotypic protein from a patient with B cell lymphoma and used a synthetic peptide of 22 amino acids corresponding to the VH complementarity‐determining region (CDR)‐3 of the idiotypic protein to investigate whether autologous T cells could recognize this unique peptide. We demonstrated that autologous T cells possessing both CD4+ and CD8+ phenotypes could be propagated. The T cells were able to proliferate, secrete cytokines, and lyse autologous cells presensitized with the specific peptide in a major histocompatibility complex‐dependent manner. Moreover, these CDR3 peptide‐primed T cells were also able to kill autologous lymphoma cells. Our results therefore offer new perspectives for specific therapeutic vaccination for the treatment of B cell lymphoma.
Post‐translational up‐regulation of the cell surface‐associated α component of the human type I interferon receptor during differentiation of peripheral blood monocytes: role in the biological response to type I interferon
Authors: Fantuzzi Laura , Eid Pierre , Malorni Walter , Rainaldi Gabriella , Gauzzi Maria C. , Pellegrini Sandra , Belardelli Filippo , Gessani Sandra 
Published: March 2007

AbstractHuman peripheral blood monocytes cultured in vitro exhibit a greater sensitivity to the antiviral effect of type I interferon (IFN) compared to freshly isolated monocytes. We evaluated the effect of macrophage differentiation on the expression of type I IFN receptors (IFN‐R). Binding studies with iodinated IFN‐α2 and Scatchard plot analysis revealed that a single class of high‐affinity receptors was present in freshly isolated monocytes. Monocyte differentiation to macrophages resulted in a three‐ to fourfold increase in the number of cell surface receptors with no change in their affinity. Polymerase chain reaction analysis of RNA revealed that comparable levels of mRNA for the IFN‐R α (IFNAR1) and IFNAR2 components were expressed in freshly isolated monocytes and 7‐day cultured macrophages. Likewise, the levels of IFNAR1 protein remained constant over time in culture. Immunofluorescence studies revealed that IFNAR1 was localized in intracellular compartments of freshly isolated monocytes, whereas it was predominantly detected on the cell surface in 7‐day cultured macrophages. The increased expression of IFN‐R on the plasma membrane of cultured macrophages may, at least in part, account for the increased antiviral efect of type I IFN in these cells. These modifications represent one of the events occurring during monocyte differentiation that may play a role in the regulation of macrophage functions.
Constitutive and inducible protein/DNA interactions of the interferon‐γ promoter in in vivo CD45RA and CD45RO T helper subsets
Authors: Barbulescu Karina , Zum Büschenfelde Karl‐Hermann Meyer , Neurath Markus F. 
Published: March 2007

AbstractInterferon‐γ (IFN‐γ) is a key cytokine of T lymphocytes with major regulatory functions in the immune system. To determine and compare protein/DNA interactions at the native IFN‐γ locus in T cells, we analyzed the human IFN‐γ promoter by ligation‐mediated polymerase chain reaction (LM‐PCR) techniques. Accordingly, Jurkat T cells and primary CD45RA and CD45R0 CD4+ T cell subsets isolated from peripheral blood using immunomagnetic beads were cultured and analyzed by LM‐PCR. Constitutive and inducible protein/DNA interactions of the IFN‐γ promoter in vivo were detected in all T cells tested. Interestingly, an inducible footprint between − 183 and − 196 was consistently observed in Jurkat T cells and CD45RA and CD45R0 T helper subsets upon stimulation with phorbol 12‐myristate 13‐acetate + phytohemagglutinin (PMA + PHA) that was highly sensitive to treatment with corticosteroids. This novel target site, denoted the C‐site, was shown by several criteria, including cell distribution studies, stimulation experiments, supershift assays, and cross‐competition electrophoretic mobility shift assays to bind the transcription factor AP‐1. Mutation of the C‐site that prevented AP‐1 binding to this site was sufficient strikingly to reduce inducible promoter activity in primary CD45R0 T cells. In summary, the data demonstrate that IFN‐γ gene transcription in primary T cells is regulated in vivo at the level of constitutive and inducible protein/DNA interactions. We propose a model where basal transcription is maintained by binding of various transcription factors to the IFN‐γ promoter, whereas PMA + PHA‐inducible IFN‐γ transcription in CD45R0 T cells is associated with binding of AP‐1 to the C‐site.
Influences on the lifespan of B cell subpopulations defined by different phenotypes
Authors: Fulcher David A. , Basten Antony 
Published: March 2007

AbstractThe turnover of mature and immature B cells defined by a range of cell surface markers was investigated by feeding normal or bcl ‐2‐transgenic (bcl‐2‐Tg) mice 5'‐bromo‐2‐deoxyuridine (BrdUrd) for up to 6 weeks. In peripheral lymphoid tissue, B cells accumulated BrdUrd with a 50% labeling time of 4.3 weeks and a pattern of uptake indicative of the presence of both long‐lived and short‐lived cells. These two kinetic populations could be resolved into immature B220lo/heat‐stable antigen (HSA)hi cells which labeled rapidly, and B220hiHSAlo cells which were uniformly long‐lived with a half‐life of about 6 weeks. During loading and pulse‐chase experiments, BrdUrd uptake by cells within the mature B220hiHSAlo population clearly followed an exponential kinetic pattern, suggesting that their loss was governed by stochastic processes. Using other surface markers, the long‐lived population could also be defined by high expression of IgD, representing cells in the follicular mantle zone of the spleen, and by the phenotype IgMhiIgDloHSAlo which most likely represented marginal zone memory B cells. CD23 expression on B cells did not differentiate well between long and short‐lived cells. Only about half of newly labeled B cells appearing in the spleen progressed to the long‐lived compartment, a proportion which was not altered significantly in bcl ‐2‐Tg mice. The most likely explanation was that a combination of both positive and negative selection was operating at this site which was mediated by pathways not regulated by bcl‐2. On the other hand, overexpression of bcl‐2 did result in a two‐to threefold increase in the rate of appearance of newly labeled B cells in the spleen, consistent with a possible role for this protein during early selection events within the bone marrow. Selection processes appeared to be very active in young mice during the shaping of the B cell repertoire, since B cells from 6‐week‐old non‐Ig mice displayed a rapid rate of turnover irrespective of their surface phenotype, and a significant population of long‐lived cells did not become evident until the mice had reached about 12 weeks of age.
Regulation of transforming growth factor‐β production by interleukin‐12
Authors: Marth Thomas , Strober Warren , Seder Robert A. , Kelsall Brian L. 
Published: March 2007

AbstractThe induction of peripheral tolerance following oral antigen administration in several autoimmune disease and conventional animal models correlates with the production of transforming growth factor‐β (TGF‐β) and T helper type 2 (Th2) cytokines. The factors regulating TGF‐β production and its relation to the Th2 response, however, have not been defined. We demonstrate that the systemic administration of antibodies to interleukin (IL)‐12 to ovalbumin (OVA)‐T cell receptor (TCR) transgenic mice fed high doses of OVA, followed by systemic OVA challenge, substantially enhances TGF‐β, but not IL‐4 production by peripheral T cells. Furthermore, we demonstrate in an in vitro T cell differentiation model that naive (CD4+/Mel‐14hi) OVA‐TCR‐T cells stimulated with OVA‐pulsed dendritic cells (DC) produce four‐to fivefold higher amounts of TGF‐β when cultured with anti‐IL‐12 or anti‐interferon‐γ (IFN‐γ). In this in vitro system, IL‐4 was not required for TGF‐β production by T cells; however, it appeared to enhance levels of TGF‐β by promoting the growth of TGF‐β‐producing cells. Our findings demonstrate that IL‐12 and IFN‐γ are important negative regulators of TGF‐β production both in vivo and in vitro, and that their modulation may be of benefit for the treatment of autoimmune disorders.
Sox‐4 facilitates thymocyte differentiation
Authors: Schilham Marco W. , Moerer Petra , Cumano Ana , Clevers Hans C. 
Published: March 2007

Abstract1he mouse Sry‐like transcription factor Sox‐4 is expressed in thymus, bone marrow, and gonads of adult mice. Sox‐4‐deficient mice die at embryonic day E14 due to cardiac malformation. In transfer experiments to irradiated recipients, B cell development was shown to be severely impaired in Sox‐4‐deficient progenitor cells. However, no drastic effects on T lymphocyte development were noted, despite the high level expression of the Sox‐4 gene in the thymus of normal mice. Here, we report a detailed analysis of T cell development from Sox‐4‐deficient progenitors. Explanted fetal thymic organ cultures (FTOC) of Sox‐4‐deficient thymi yielded 10–50‐fold fewer CD4 CD8 double‐positive and single‐positive cells than FTOC of littermates. This effect was T cell‐autonomous, since similar observations were made when FTOC were performed by culturing of Sox‐4‐deficient progenitors in wild‐type thymus lobes. When Sox‐4‐deficient fetal liver cells were injected together with normal cells intrathymically, they did not compete efficiently for reconstitution. It is concluded that Sox‐4 facilitates thymocyte development.
Maturation of Peyer's patch dendritic cells in vitro upon stimulation via cytokines or CD40 triggering
Authors: Ruedl Christiane , Hubele Sabine 
Published: March 2007

AbstractIn mouse Peyer's patches (PP), dendritic cells (DC) are localized in T cell areas as NLDC145+ CD11c+ cells, and in the dome and corona region of the follicle as NLDC145− CD11c+ cells, respectively, suggesting the presence of two different DC populations with distinct roles in antigen uptake, processing, and presentation. However, it is not clear how this relates to DC maturation. In this report, we demonstrate that freshly‐isolated CD11c+ DC have the properties of immature DC since they endocytose soluble antigens, phagocytose particulate material such as latex beads, synthetize major histocompatibility complex (MHC) class II and invariant chain, but, at the same time, display low stimulatory activity for resting T cells, as shown in mixed‐lymphocyte reaction and oxidative mitogenesis assays. When cultured for 24 h in the presence of the cytokines granulocyte‐macrophage colony‐stimulating factor and tumor necrosis factor or anti‐CD40, the cells undergo dramatic phenotypic and functional changes characteristic of DC maturation. After 24 h stimulation in vitro, CD11c+ cells lose the ability to take up proteins such as ovalbumin, and in parallel with this decline, the biosynthesis of MHC class II and invariant chain is dramatically down‐regulated or eliminated. On the other hand cells treated in vitro exhibit on the cell surface higher levels of MHC class II, of co‐stimulatory molecules (CD80, CD86), of adhesion molecules (CD44, intercellular adhesion molecule‐1), and acquire expression of the interdigitating DC surface marker NLDC145. Concomitantly, the ability to stimulate naive T cells drastically increased after in vitro treatment with both stimuli. Taken together, our results indicate that the majority of DC in the PP are immature in terms of their antigen‐uptake capacity. These sentinel antigen presenting cells are strategically positioned at the dome region of PP, where antigens are transcytosed via the M cells from the gut lumen. A second population of mature interdigitating NLDC145+ CD11c+ DC stimulates naive unprimed T cells in interfollicular areas by up‐regulation of surface ligands and accessory signals.
HLA‐B27 modulates intracellular survival of Salmonella enteritidis in human monocytic cells
Authors: Laitio PÄIvi , Virtala Mika , Salmi Marko , Pelliniemi Lauri J. , Yu David T. Y. , Granfors Kaisa 
Published: March 2007

AbstractHuman major histocompatibility complex class I allele HLA‐B27 is associated with a group of diseases called spondyloarthropathies. In reactive arthritis (ReA), the disease is triggered by certain infections, e.g. gastroenteritis caused by Salmonella. The host/microbe interaction is abnormal in susceptible individuals leading to inefficient elimination of arthritis‐triggering bacteria, fragments of them, or both, after the initial infection. Using transfected human monocytic U937 cell lines, we demonstrate that the expression of the HLA‐B27 antigen does not influence the uptake of S. enteritidis into U937 cells in vitro. Interestingly, HLA‐B27 remarkably impairs the elimination of S. enteritidis within the HLA‐B27 transfected U937 cells. The impaired elimination of ReA‐triggering microbes by HLA‐B27+ monocytes may offer an explanation for the persistence of ReA‐triggering microbes in susceptible HLA‐B27+ individuals. This modulation of the host/microbe interaction by HLA‐B27 may have an important role in the pathogenesis of ReA.
Direct cell/cell communication in the lymphoid germinal center: connexin43 gap junctions functionally couple follicular dendritic cells to each other and to B lymphocytes
Authors: Krenacs Tibor , van Dartel Maike , Lindhout Ernst , Rosendaal Martin 
Published: March 2007

AbstractDirect cell/cell communication occurs through gap junctions (GJ). We mapped GJ expression in secondary lymphoid organs and found, for the first time, a high density of connexin43 (Cx43) GJ in follicular dendritic cells (FDC) in close association with lymphocytes (Krenacs T. and Rosendaal M., J. Histochem. Cytochem. 1995. 43: 1125–1137). In this work, we used a combination of ultrastructural, immunocytochemical, molecular methods, and functional dye transfer experiments to study which germinal center cells are involved in direct cell/cell communication and how GJ expression is regulated during antigen responses. One week after injecting the footpad of mice with 50 μg lysozyme, Cx43 GJ were detected on elongated cells in the paracortex of their popliteal lymph nodes. Repeated challenge led to the formation of secondary follicles with enlarged FDC meshwork full of Cx43 GJ. This positive correlation may reflect an importance for GJ in the pattern formation of FDC and lymphoid follicles. In human tonsil, the density of GJ and FDC was highest in the light zone of germinal centers where the fate of B cells is thought to be decided. Cx43 colocalized with CD21 and CD35 antigens in the vicinity of desmosomal junctions on FDC embracing lymphocytes. Freeze‐fracture hallmarks of GJ of 200–400 nm were also found on FDC in the vicinity of desmosomal plaques. Furthermore, Northern blot analysis showed the consistent presence of Cx43 mRNA in human tonsil and spleen. Most Cx43 message was localized in situ to cells with FDC morphology and some to a few germinal center lymphocytes. To investigate functional cell coupling, we set up FDC/B cell cultures from the low density cell fractions of human tonsils. Cx43 plaques associated with lymphocytes were detected both on elongated FDC processes in early cultures (up to 4 h) and in established FDC/B cell clusters (between 4 and 24 h). In early cultures, we injected FDC with Lucifer Yellow, a fluorescent dye which passes through GJ: the dye spread into adjacent FDC and occasionally from FDC into CD19+ B cells. Based on these results, we propose that direct cell/cell communication through Cx43 GJ is involved in FDC/FDC and in FDC/B cell interactions. The functionally coupled FDC meshwork may serve as a communication channel synchronizing germinal center events. FDC may also deliver crucial direct signals through GJ involved in the rescue of high‐affinity B cell clones from apoptotic cell death.