bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tyrosine kinase activation in thymic epithelial cells: necessity of thymocyte contact through the gp23/45/90 adhesion complex
Authors: Coutrure Clément , Amarante‐Mendes Gustavo , Potworowski Edouard F. 
Published: March 2007

AbstractInteractions between thymocytes and thymic stromal cells are necessary for T cell differentiation, maturation and proliferation. The signals required for these events to occur often necessitate close contact, and indeed adhesion, between the cell types involved. While the transmission of signals from stromal cells to thymocytes has been well documented, there is little evidence that binding of thymocytes to stromal cells can result in stromal cell activation. We have recently identified a novel thymic epithelial adhesion complex composed of three non‐covalently associated glycoproteins (gp23, gp45 and gp90). While gp23 and gp45 are jointly required for adhesion to thymocytes, the function of gp90 is unknown. In the present work, we show that gp23/45‐mediated contact with thymocytes induces de novo tyrosine phosphorylation of gp90. Furthermore, the protein tyrosine kinase responsible for gp90 neophosphorylation is itself an integral part of the adhesion complex.
Analysis of human/mouse interleukin‐6 hybrid proteins: both amino and carboxy termini of human interleukin‐6 are required for in vitro receptor binding
Authors: Fiorillo Maria Teresa , Cabibbo Andrea , Iacopetti Paola , Fattori Elena , Ciliberto Gennaro 
Published: March 2007

AbstractThe multifunctional cytokine interleukin‐6 (IL‐6) is a single polypeptide chain consisting of 184 amino acids in man and 187 amino acids in mouse. Despite the relatively high degree of sequence similarity of these two molecules (about 57%), the biological activity in mouse and human IL‐6 shows species specificity. Starting with this observation, we constructed interspecies hybrids with the goal of defining which segments of the human IL‐6 molecule are involved in human receptor binding. In this manner we generated multiple amino acid substitution mutants which do not contain insertions or deletions as compared with the parental proteins, and which, therefore, should not show dramatic changes in folding. Using two biological assays on cells of human and mouse origin and a recently developed in vitro binding assay to recombinant soluble human IL‐6 receptor, we obtained results which indicate that both the amino and carboxy termini are necessary and sufficient for efficient binding, but that the carboxy terminus plays the dominant role in receptor recognition.
Molecular detection and in vivo analysis of the specific T cell response to a protein antigen
Authors: Cochet Madeleine , Pannetier Christophe , Regnault Armelle , Darche Sylvie , Leclerc Claude , Kourilsky Philippe 
Published: March 2007

AbstractWe have analyzed in detail the repertoire of transcripts encoding the Vβ chains of the T cell receptor and investigated the T cell response of B10.A mice to pigeon cytochrome c. We were thus able to follow the specific T cell response in vivo after immunization with this protein antigen. The response is first detectable in the draining lymph nodes, then in the spleen and in the blood. It is qualitatively similar in individual animals. It is dominated by a major category of specific T cells harboring a Vβ3‐Jβ1.2 rearrangement, and a limited and well‐defined set of nucleotide sequences, previously found in several specific T cell hybridomas and clones. This predominance is observed from the onset of the immune response strongly suggesting the notion that there is no variation and, therefore, no maturation of the T cell response in the course of immunization.
The CD39 molecule defines distinct cytotoxic subsets within alloactivated human CD8‐positive cells
Authors: Gouttefangeas Cécile , Mansur Indra , Schmid Michel , Dastot Hélène , Gélin Catherine , Mahouy Guy , Boumsell Laurence , Bensussan Armand 
Published: March 2007

AbstractLymphocyte activation induces or increases the expression of several surface structures, none of which is characteristic of an activated cell subset. In particular, structures such as CD45RO, CD25, CD26, CD49b, CD54, CD71 are expressed by the vast majority of lymphocytes at various times following in vitro activation. CD39 molecules were originally identified on activated B lymphocytes and have recently been described on activated T cell clones. In the present report, we have characterized phenotypically and functionally defined cell subsets generated during an in vitro allostimulation. Results indicated that the percentage of CD39+ cells reached a maximum at day 6 and remained stable thereafter. We demonstrate that CD39 expression allows the identification within the allosensitized CD8+ cytotoxic cells of distinct subsets of cells mediating allo cytotoxic T lymphocyte or natural killer (NK)‐like reactivity. More precisely, CD8+CD39+ alloactivated cells mainly mediate specific killer activity, whereas CD8+CD39− alloactivated cells predominantly exhibit NK‐like reactivity. Further, we show a high functional correlation associated with the lack of CD39 expression on NK‐like alloactivated CD8+ cells, while there is no association with CD56 or CD57 NK‐associated structures.
Leukotriene B4 transcriptionally activates interleukin‐6 expression involving NK‐xB and NF‐IL6
Authors: Brach Marion A. , De Vos Sven , Arnold Christian , Gruß Hans‐Jürgen , Mertelsmann Roland , Herrmann Friedhelm 
Published: March 2007

AbstractLeukotriene B4 (LTB4) is a notable participant in inflammation and chemotaxis. It is, however, still unclear whether LTB4 acts in this regard directly or indirectly by stimulating the release of chemotactic and inflammatory cytokines. Here we report that LTB4 induces synthesis of interleukin (IL)‐6 by human blood monocytes through transcriptional activation of the IL‐6 gene. We furthermore demonstrate that this process involves activation of the transcription factor NF‐xB and, to a lesser extent, of NF‐IL6, while the activity of the transcription factor AP‐1, shown to otherwise confer IL‐6 inducibility, appeared to be unaffected by LTB4. Involvement of NF‐xB and NF‐IL6 in induction of IL‐6 transcription by monocytes was demonstrated using deleted forms of the IL‐6 promoter. Activation of the IL‐6 promoter by LTB4 was not only associated with accumulation of the respective transcripts but resulted in synthesis of functional IL‐6 protein as well. In addition, LTB4 mediated transactivation of a heterologous promoter construct containing the NF‐xB or the NF‐IL6 enhancer, but not the AP‐1 enhancer. The signaling events mediating this effect appeared to involve the release of H2O2, since LTB4 failed to induce NF‐xB or NF‐IL6 in the presence of the scavenger of H2O2, N‐acetyl‐L‐cysteine.
Effects of HIV‐1 Tat protein on human T cell proliferation
Authors: Meyaard Linde , Otto Sigrid A. , Schuitemaker Hanneke , Miedema Frank 
Published: March 2007

AbstractIn inducing immunodeficiency in human immunodeficiency virus (HIV)‐1 infection, a role for the HIV‐1 Tat protein has been suggested. In addition to effects on viral transcription, the protein has been ascribed immunosuppressive functions, which were investigated in this study. Proliferation of purified T cells to CD3 monoclonal antibodies immobilized to plastic plates was inhibited up to 70% by addition of 5 μg/ml of the Tat protein. This inhibitory effect, however, was not observed in the presence of accessory cells. Furthermore, no effect of Tat protein could be observed on T cell proliferative responses to recall antigen which most likely is related to the presence of accessory cells in the cultures. Taken together, our results do not imply an important role for immunosuppressive effects of Tat in induction of immunodeficiency as observed in HIV infection in vivo.
Nitric oxide mediates suppression of T cell responses in murine Trypanosoma brucei infection
Authors: Sternberg Jeremy , McGuigan Fiona 
Published: March 2007

AbstractAfrican trypanosomes induce a generalized state of immunosuppression in their mammalian hosts. One characteristic of this is a suppression of lymphocyte responses to mitogen, which is mediated by suppressor macrophages. We investigated the involvement of nitric oxide in this phenomenon. Both peritoneal and splenic cell cultures from infected mice released nitrite and this was inhibitable by NG‐monomethyl L‐arginine (L‐NMMA). The release of nitrite correlated with suppressed splenic T cell proliferative responses to concanavalin A. It was shown that adherent spleen cells from infected mice mediate suppression, which could be abrogated by L‐NMMA. These results suggest that in T. brucei infection, the activation of macrophages to produce nitric oxide leads to impaired lymphocyte responses and immunosuppression.
Quantitative analysis of the response of human T cell receptor Vγ9+ cells to Plasmodium falciparum
Authors: Goodier Martin , Krause‐Jauer Maria , Langhorne Jean 
Published: March 2007

AbstractPlasmodium falciparum stimulates peripheral blood γδ+ T cells from unexposed donors. The responding cells bear Vγ9+ chains of the T cell receptor, the majority of which, but not all, are associated with Vγ2 chains. We have analyzed whether the precursor frequency of these Vγ9+ cells approaches that expected of superantigens or mitogens and whether, like a superantigen, the response is major histocompatibility complex (MHC) unrestricted. Limiting dilution analyses of the response of enriched γδ+ T cells to P. falciparum using autologous and heterogolous antigen‐presenting cells suggest that the response is more characteristic of an antigen‐specific MHC‐restricted response. The frequencies are lower than would be expected if all Vγ9+ cells respond, and there is a dramatically reduced response when allogeneic antigen‐presenting cells are used.
High frequency of somatically mutated IgM molecules in the human adult blood B cell repertoire
Authors: Van Es Johan H. , Meyling Frits H. J. Gmeli , Logtenberg Ton 
Published: March 2007

AbstractNucleotide sequence analysis of cDNA encoded by the single member of the human immunoglobulin VH6 gene family show that blood B cells in adults, but not in neonates, frequently express somatically mutated IgM molecules. The number of mutations in VH6‐encoded cDNA from adult blood ranged from 2 to 19 mutations/VH gene (average 10.1/VH gene). The distribution of silent and replacement mutations suggests that at least some of the VH6 genes were derived from B cells that were activated and selected by antigen. We conclude that the blood B cell repertoire in adult humans, in contrast to its much‐studied murine splenic counterpart, is a rich source of highly mutated IgM molecules.
Regulation of interleukin‐4 production in human mononuclear cells
Authors: Holter Wolfgang , Majdic Otto , Kalthoff Frank S. , Knapp Walter 
Published: March 2007

AbstractInterleukin (IL)‐4 is a cytokine with a broad range of effects on immune cells, however, little is known regarding the regulation of its production in freshly isolated human peripheral blood mononuclear cells (PBMC). Here we report the production of IL‐4 in such cells following stimulation with monoclonal antibodies (mAb) directed against different cell surface antigens. We show that triggering via CD2 is more efficient for IL‐4 production than triggering via the CD3 complex. The addition of a CD28 mAb enhances IL‐4 production approximately threefold. Cell depletion experiments show that among CD2 plus CD28‐stimulated PBMC the production of IL‐4 is restricted to the CD8−CD45RA−T cell subpopulation. mAb interfering with the binding of IL‐2 to its receptor can inhibit the production of IL‐4 in CD2 plus CD28‐stimulated PBMC. As IL‐2 induces cell proliferation and production of interferon‐γ, but not production of IL‐4, it follows that IL‐2 is necessary but not sufficient for IL‐4 production.
The viral superantigen Mls‐1a induces interferon‐γ secretion by specifically primed CD8+ cells but fails to trigger cytotoxicity
Authors: Herrmann Thomas , Waanders Gary A. , Chvatchko Yolande , Robson MacDonald H. 
Published: March 2007

AbstractSuperantigens can be operationally defined by their ability to stimulate CD4+ and CD8+ T cells via the T cell receptor β chain variable domain (TcR Vβ). We show here that effector functions of CD8+ T cells specific for superantigens differ depending upon the nature of the superantigen involved. Hence, activated CD8+ T cells bearing TcR Vβ specific for the superantigen Mls‐1a [encoded in the open reading frame of the 3′ long terminal repeat of endogenous mouse mammary tumor virus (MMTV)] are unable to lyse Mls‐1a‐bearing target cells despite the fact that they release interferon‐γ (IFN‐γ) upon Mls‐1a stimulation. In contrast CD8+ T cells specific for the exogenous superantigen staphylococcal enterotoxin B (SEB) readily mediate both lysis and IFN‐γ secretion when exposed to SEB‐bearing target cells. This dissociation between lysis and IFN‐γ production by Mls‐1a‐specific CD8+ T cells is independent of the initial stimulus used for activation and appears not to be simply explained by a low Mls‐1a determinant density. We suggest that this phenomenon reflects differing TcR affinity thresholds for lymphokine secretion and cytolysis. Such differences may be exploited by retroviruses such as MMTV in order to escape immunosurveillance.
Human growth factor for murine interleukin (IL)‐9 responsive T cell lines: co‐induction with IL‐6 in fibroblasts and identification as LIF/HILDA
Authors: Van Damme Jo , Uyttenhove Catherine , Houssiau Frédéric , Put Willy , Proost Paul , Van Snick Jacques 
Published: March 2007

AbstractTwo mouse helper T cell clones that proliferate in response to murine interleukin (IL)‐9 could also be grown in conditioned medium of stimulated human connective tissue cells. The activity was not due to known T cell growth factors including human IL‐9, which is not effective on mouse cells. This growth‐stimulatory activity for TS1 cells (GATS) was co‐induced with IL‐6 on normal fibroblasts and certain sarcoma cell lines stimulated with IL‐1, double‐stranded RNA, virus or phorbol ester. However, the conditions for optimal induction and the kinetics of production were found to be different for IL‐6 and GATS. GATS from phorbol ester‐stimulated human hepatosarcoma cells co‐purified with IL‐6, but could be separated from it by subsequent cation‐exchange fast‐protein liquid chromatography and reverse‐phase high‐performance liquid chromatography. Homogeneous tumor cell‐derived GATS was a 25‐kDa protein on sodium dodecyl sulfate‐polyacrylamide gel electrophoresis, whereas IL‐6 produced by these cells appeared in its 23‐kDa form. Pure GATS was found to be inactive in the B cell hybridoma growth assay for IL‐6. Finally, GATS was identified by NH2‐terminal sequence analysis of the mature protein as leukemia inhibitory factor or human interleukin for DA cells (LIF/HILDA). The effect of LIF/HILDA on T cells was not mediated by IL‐2, IL‐4 or IL‐9 production. Since this cytokine has not previously been reported to act on T cells, further investigation of its role in T cell activation should be taken into consideration.
High amounts of circulating interleukin (IL)‐6 in the form of monomeric immune complexes during anti‐IL‐6 therapy. Towards a new methodology for measuring overall cytokine production in human in vivo
Authors: Lu Zhao Yang , Brochier Jean , Wijdenes John , Brailly Hervé , Bataille Régis , Klein Bernard 
Published: March 2007

AbstractA patient with plasma cell leukemia was treated with anti‐interleukin (IL)‐6 monoclonal antibodies (mAb) for 2 months. Using chromatography on protein A‐Sepharose, anti‐murine‐IgG‐Sepharose, anti‐IL‐6‐mAb‐Sepharose and gel filtration at pH 2.3, we have demonstrated that the anti‐IL‐6 mAb, by preventing the binding of IL‐6 to its cell membrane receptor and its renal elimination, has induced huge amounts of IL‐6 to circulate in the form of monomeric immune complexes. By using this observation, we have developed a mathematical modelling that allows the determination of the overall daily production of IL‐6 in this patient, which was in the range of 15 μg per day. Overall in vivo production of cytokines has never been evaluated in animals or in humans before.
Co‐stimulation of murine CD4 T cell growth: cooperation between B7 and heat‐stable antigen
Authors: Liu Yang , Jones Bryan , Brady William , Janeway Charles A. , Linley Peter S. 
Published: March 2007

AbstractThe B cell activation antigen B7/BB1 has been shown to co‐stimulate growth of human T cells by binding the T cell molecule CD28. In mice, the heat‐stable antigen (HSA) has also been shown to act as a co‐stimulator for T cell growth. In this study, we have evaluated the contributions of B7 and HSA to the co‐stimulatory activity of antigen‐presenting cells (APC). Mouse B7 provides co‐stimulatory activity for murine CD4 T cells in anti‐CD3‐induced proliferation. Human CTLA4Ig, a chimeric molecule comprising the extracellular region of CTLA‐4 fused to an immunoglobulin Cγ fragment, binds to murine B7. We, therefore, use human CTLA4Ig and the hamster anti‐HSA monoclonal antibody 20C9 to analyze the relative contributions of B7 and HSA to the co‐stimulatory activity of murine spleen APC. Our data reveal that both murine B7 and HSA are expressed by dendritic cells and by low‐density spleen B cells. Either CTLA4Ig alone or anti‐HSA alone inhibited CD4 T cell proliferation to anti‐CD3 by > 90%, while CTLA4Ig and anti‐HSA together were far more efficient in inhibiting clonal expansion of CD4 T cells. These results demonstrate that functionally defined co‐stimulation involves at least B7 and HSA and suggest that signals delivered by B7 and HSA synergize in promoting T cell growth.
Interleukin‐4 differentially regulates interleukin‐2‐mediated and CD2‐mediated induction of human lymphokine‐activated killer effectors
Authors: Robinet Eric , Kamoun Malek , Farace Françoise , Chouaib Salem 
Published: March 2007

AbstractNatural killer (NK) cells can be differentiated into lymphokine‐activated killer (LAK) effectors following stimulation with interleukin (IL)‐2. This induction can be negatively regulated by IL‐4. In this study, we demonstrate that the stimulation of NK cells through the CD2 pathway with (9‐1 + 9.6) monoclonal antibodies can also induce these cells to secrete tumor necrosis factor‐α (TNF‐α) and to differentiate into LAK effectors. More importantly, our data indicate that, in contrast to the IL‐2‐induced LAK generation, the anti‐CD2‐triggered LAK activity was not regulated by IL‐4. IL‐4 was found to enhance the LAK activity as well as NK cell proliferation following activation with anti‐CD2 by a mechanism involving, at least in part, an increased TNF‐α production. Using immobilized monoclonal antibodies against the Fc receptor (FcγRIII or CD16) for NK stimulation, we also observed that the anti‐CD16‐induced LAK activity was not inhibited by IL‐4.These data further point to a pivotal role of TNF‐α as a regulatory cytokine in anti‐CD2‐induced LAK generation, and suggest that IL‐4 could serve as a discriminatory factor between two distinct pathways involved in the activation of non‐MHC‐restricted cytotoxicity.
Molecular characterization of the Vγ9 T cell receptor repertoire expressed in patients with rheumatoid arthritis
Authors: Olive Colleen , Gatenby Paul A. , Serjeantson Susan W. 
Published: March 2007

AbstractWe have characterized the variable (V)γ9 T cell receptor (TcR) repertoire expressed in synovial membrane (SMC) and peripheral blood mononuclear cells (PBMC) of five rheumatoid arthritis (RA) patients. The experimental approach was to sequence the junctional regions of polymerase chain reaction (PCR)‐amplified Vγ9 transcripts; γ chain sequences were compared with those found in normal PBMC. For normal PBMC, a large proportion of Vγ9 transcripts used the joining (J)γP gene segment whereas a few used Jγ2. Despite this restriction in Jγ usage, there was extensive junctional region diversity with a unique sequence observed in each transcript examined. In contrast to normal PBMC, Jγ usage of Vγ9 transcripts in PBMC of two patients was skewed towards Jγ2. This deviation in Jγ usage was more pronounced in SMC since all patients expressed Vγ9 transcripts in SMC which predominantly used Jγ2, as opposed to JγP in normal PBMC. Further, approximately 60% of Vγ9 transcripts in PBMC of each of three patients had identical junctional region sequences, although the specific sequences were unique in each patient. For two of these patients the dominant transcript found in the PBMC was detected in the corresponding SMC at about 10% and 40%, respectively. Overall, our findings indicate that Vγ9‐bearing T cells in RA peripheral blood are largely derived from clonal expansion whereas in the synovium there is expression of a population of these cells that are mainly polyclonal. This may reflect in vivo expansion in response to a Vγ9/Jγ2 region‐specific antigen. The data presented in this report suggest that Vγ9+ T cells may play a role in the development of RA.
Both T cell receptor (TcR)‐CD3 complex and CD2 increase the tyrosine kinase activity of p56lck. CD2 can mediate TcR‐CD3‐independent and CD45‐dependent activation of p56lck
Authors: Danielian Silvia , Alcover Andrés , Polissard Laurence , Stefanescu Maria , Acuto Oreste , Fischer Siegmund , Fagard Remi 
Published: March 2007

AbstractT cell activation by triggering the T cell receptor (TcR)‐CD3 complex leads to a dramatic increase in tyrosine phosphorylation of multiple cellular proteins. To date, there has been no direct evidence on the identity of the tyrosine kinase activity implicated in this signaling pathway. In this study, we demonstrate that activation of human T cells with anti‐CD3 monoclonal antibody increases tyrosine kinase activity of p56lck. This extends our previous findings which demonstrated the involvement of p56lck kinase activity in the CD2 signal transduction pathway. The results from peripheral blood lymphocytes and Jurkat cell line showed in both cases an early and transient change in the specific activity of p56lck, followed by a shift to a higher apparent molecular mass. Therefore, to test directly the role of TcR‐CD3 in CD2‐induced activation of p56lck, we utilized mutant variants of the Jurkat cell line lacking in cell surface TcR‐CD3. We found that cell surface expression of TcR‐CD3 is not required for the activation of p56lck via CD2 but is necessary for the appearance of the reduced‐electrophoretic‐mobility form of p56lck observed after CD2 triggering. By isolating CD45‐ mutants from Jurkat cells, we observed that surface expression of the tyrosine phosphatase CD45 is required in order to increase p56lck activity following CD2 stimulation, while CD4‐induced activation of the kinase remained unchanged. These data provide evidence for a specific functional linkage between CD2 and p56lck, in which CD45 may play an essential role.