bluuebunny/crossref_metadata_2025_split huggingface dataset:
Role of CD40 antigen and interleukin‐2 in T cell‐dependent human B lymphocyte growth
Authors: Blanchard Dominique , Gaillard Claude , Hermann Patrice , Banchereau Jacques 
Published: March 2007

AbstractIn the present study, we examined the participation of CD40 ligand (L)‐CD40 interaction in T cell‐dependent B cell responses. To this end, purified B lymphocytes were cultured over irradiated CD4+ cloned T cells activated with immobilized anti‐CD3 antibody. The anti‐CD40 mAb 89 strongly blocked, in a specific fashion, both proliferation and Ig secretion of tonsil B cells. Interestingly, proliferation of surface (s)IgD+ B cell was significantly less inhibited by anti‐CD40 than that of sIgD− cells. Preactivated T cells induced B cells to grow and secrete immunoglobulins preferentially in response to IL‐2. This contrasts with the CD40 system where B cells are essentially responsive to IL‐4 and IL‐10 but not to IL‐2 alone. Collectively, these data indicate that CD40L‐CD40 interaction plays an important role in IL‐2‐mediated T cell‐dependent B cell responses. However, the activation of a subset of sIgD+ cells may be independent of this interaction.
Differential effects of interleukin‐12 on the development of naive mouse CD4+ T cells
Authors: Schmitt Edgar , Hoehn Petra , Germann Tieno , Rüde Erwin 
Published: March 2007

AbstractThe influence of interleukin (IL)‐12 and IL‐4 on the differentiation of naive CD4+ T cells was studied in an accessory cell‐free in vitro system. Dense CD4+ T cells were purified from unimmunized mice and activated using immobilized anti‐CD3 monoclonal antibodies (mAb) in the presence of IL‐4, IL‐12, or a combination of both cytokines, and restimulated after 6 days by re‐exposure to anti‐CD3‐coated culture wells. T cells initially activated in the presence of IL‐4 produced substantial amounts of IL‐4 and trace amounts of interferon (IFN)‐γ after restimulation at day 6 with plate‐bound anti‐CD3 mAb. By contrast, T cells primed in the presence of IL‐12 produced high levels of IFN‐γ and only minimal amounts of IL‐4, thus indicating that IL‐12 and IL‐4 by acting directly on stimulated naive CD4+ T cells support the development of TH1 and TH2 cells, respectively. When naive CD4+ T cells were stimulated in the presence of IL‐12 together with IL‐4 in comparable concentrations, the effect of IL‐12 on TH1 differentiation was largely inhibited by IL‐4. On the other hand, IL‐12 exerted no inhibitory effect on IL‐4‐induced TH2 differentiation but rather enhanced the production of IL‐4 after restimulation of the respective T cells. Decreasing amounts of IL‐4 in combination with a high level of IL‐12 led to an increasing production of IFN‐γ by the emerging T cells and, simultaneously, to a relatively high production of IL‐4. These data were confirmed by time‐course experiments which revealed that the delayed addition of IL‐4 to IL‐12‐primed T cell cultures resulted in a gradual restoration of IFN‐γ production whereas in parallel the secretion of IL‐4 was not reduced over a wide period of delay (6–72 h). These results, therefore, demonstrate that (a) IL‐4 dominates the effect of IL‐12, (b) IL‐12 promotes the development of TH1 cells; however, in the presence of IL‐12 and relatively high levels of IL‐4 also the development of TH2‐like cells is slightly but significantly enhanced by IL‐12, and (c) high amounts of IL‐12 in combination with relatively low levels of IL‐4 give rise to a T cell population that upon rechallenge exhibited a cytokine profile resembling that of TH0 cells.
Genetic analysis of immune dysfunction in non‐obese diabetic (NOD) mice: Mapping of a susceptibility locus close to the Bcl‐2 gene correlates with increased resistance of NOD T cells to apoptosis induction
Authors: Garchon Henri‐Jean , Luan Jian‐Jian , Eloy Laure , Bédossa Pierre , Bach Jean‐François 
Published: March 2007

AbstractThe non‐obese diábetic (NOD) mouse strain provides a remarkable model for investigating the mechanisms of autoimmunity. Independent genetic analyses of this model have previously shown that chromosome 1‐linked loci were involved in the control of periinsulitis and sialitis on the one hand and of insulitis and diabetes on the other hand. In the present work, analysis of a [NOD × (NOD × C57BL/6)F1] backcross progeny allowed us to clearly dissociate two genetic regions: one was associated with periinsulitis and mapped to the middle region of chromosome 1, in the vicinity of the Bcl‐2 gene; the other was associated with insulitis and mapped to the proximal part of the chromosome. Three intermediate markers D1Mit18, D1Mit5 and D1Mit19 covering at least 25 centiMorgans between these two regions, were associated with neither periinsulitis nor insulitis. The role of the Bcl‐2‐linked region in the immune anomalies of NOD mice was further investigated in a (NOD × C57BL/6)F2 cross where the Bcl‐2nod haplotype was linked to elevated serum levels of IgG (p 0.0005). The middle region of chromosome 1 is, therefore, involved in the control of three phenotypes, including periinsulitis, sialitis and hyperIgG, pointing to Bcl‐2 as a good candidate for a cause of the NOD mouse disease. Consistent with the anti‐apoptotic function of the Bcl‐2 gene product, activated T lymphocytes from NOD mice showed a markedly increased resistance to induction of apoptosis following deprivation of interleukin‐2 when compared to those from non‐autoimmune strains. After the recent observation of the Fas gene alterations in the lpr and lprcg mutations, these findings indicate that deregulation of lymphoid cell apoptosis may be a general pathogenetic mechanism in autoimmune diseases.
Evidence for a stromal cell‐dependent, self‐renewing B cell population in lymphoid follicles of the ileal Peyer's patch of sheep
Authors: Griebel Philip J. , Ferrari Giorgio 
Published: March 2007

AbstractLymphoid follicles of the ileal Peyer's patch (PP) of young sheep function as the major source of B cells and a site of immunoglobulin (Ig) receptor diversification. However, extensive cell death in culture has restricted investigations of ileal PP follicular (iPf)B cell biology. We investigated the possibility that sustained iPfB cell proliferation may require an interaction with mesenchymal stromal cells (SC). Four SC lines, cloned from lymphoid follicles of the ileal PP, and various sheep and xenogeneic mesenchymal cells were used to characterize the nature of iPfB cell‐SC interactions. A sustained proliferative response was unique to iPfB cells, required iPfB cell‐SC contact, and SC membranes functioned as intact SC to either enhance or inhibit iPfB cell proliferative responses. The iPfB cell proliferation in SC co‐cultures was accompanied by extensive cell death and a slow decline in viable cell number. Flow cytometric analysis confirmed that viable lymphocytes, present in SC co‐cultures, were immature B cells that expressed surface IgM, with either λ or χ Ig light chain, and that SC co‐culture inhibited iPfB cell differentiation. Finally, addition of soluble anti‐sheep Ig to iPfB cell‐SC co‐cultures did not inhibit SC‐dependent iPfB cell proliferation or iPfB cell binding to SC. These data indicate that an interaction between specific SC membrane molecules and non‐Ig molecules of iPfB cells either supported or inhibited a self‐renewing proliferative response by immature (sIgMLo, BAQ44A−) iPfB cells. Finally, SC‐dependent iPfB cell proliferation was independent of T cells and extrinsic antigen which further suggests that a functionally distinct B cell population resides in lymphoid follicles of the ileal PP.
Interleukin‐2 prevention of apoptosis in human neutrophils
Authors: Pericle Federica , Liu Jin Hong , Blanchard D. Kay , Wei Sheng , Djeu Julie Y. , Diaz Jose I. , Forni Guido 
Published: March 2007

AbstractEvidence is presented that interleukin (IL)‐2 maintains viability of human polymorphonuclear cells (PMN) in culture by preventing these cells from undergoing programmed cell death (PCD) and induces the synthesis of new RNA and protein. Our laboratory has recently discovered that human PMN constitutively express IL‐2β receptor and more importantly, PMN are able to respond functionally to IL‐2 by enhanced growth inhibitory activity against an opportunistic fungal pathogen, Candida albicans. We now report that IL‐2 was able to interfere with the PCD process and reduce the number of apoptotic PMN to < 40% in 72‐h culture. Freshly isolated PMN usually underwent a timedependent aging process and > 80% of PMN cultured in medium alone for 72 h showed morphologic features of PCD as depicted by hematoxylin and eosin staining as well as by electron microscopy. During the PCD process, untreated PMN not only exhibited condensed nuclear structure and decrease in cell size, but also displayed DNA fragmentation. DNA fragmentation in PMN was prevented by IL‐2. Prevention of PCD by IL‐2 was associated with an increase in new RNA and protein synthesis in PMN, which may reflect cytokine induction, such as tumor necrosis factor, as we have recently shown. Thus, our data expands our current understanding of PMN in that they may be an active component of the immune system, with a longer life‐span when activated than expected.
Evidence for cell surface association of CD2 and LFA‐1 (CD11a/CD18) on T lymphocytes
Authors: Altin Joseph G. , Pagler Eloisa B. , Parish Christopher R. 
Published: March 2007

AbstractPrevious studies have reported an association of the cell surface adhesion molecule CD2 with the T cell receptor and with CD45 on mouse and human T lymphocytes. In this study the association of CD2 with cell surface molecules was investigated using cell surface biotinylation of T lymphocytes, coupled with immunoprecipitation using two CD2‐specific monoclonal antibodies (mAb) (RM2–5 and 12–15) and analysis by SDS‐PAGE. Although both CD2 mAb immunoprecipitated CD2 from lysates of murine lymphocytes, it was found that mAb 12–15, but not RM2–5, co‐precipitated two other molecules of 95 and 180 kDa. Subsequent studies revealed that the 95‐ and 180‐kDa molecules were associated with a subspecies of CD2 (˜ 5%) on thymocytes, the antigen‐specific T cell line D10, and splenic T cells but not B cells. Two lines of evidence were obtained consistent with the 95‐ and 180‐kDa molecules being the β and α chains of LFA‐1. Firstly, an analysis of 12–15 mAb immunoprecipitates on 4–12% gels under reducing and nonreducing conditions shows that the 95‐ and 180‐kDa molecules have a molecular weight and migration pattern identical to LFA‐1. Secondly, depletion of LFA‐1 from lysates with LFA‐1 mAb abolished the ability of CD2 mAb 12–15 to co‐precipitate the 95‐ and 180‐kDa molecules, thereby identifying these as the β and α chains of mouse LFA‐1, respectively. These results provide evidence for the first time for an association of LFA‐1 and CD2 on mouse T lymphocytes, and suggest that the association occurs with an immunologically distinct subspecies of CD2 molecules.
Central tolerance: Clonal deletion or clonal arrest?
Authors: Swat Wojciech , Boehmer Harald Von , Kisielow Pawel 
Published: March 2007

AbstractStudies in various experimental animals have shown that developing T cells with specificity for self antigens can be prevented from maturation at an early stage of development. While several in vitro and in vivo experiments have shown that the mechanism of silencing autospecific T cells is the deletion of immature CD4+8+ thymocytes other experiments were interpreted to indicate that tolerance could also result from developmental arrest of more immature CD4−8+ thymocytes not involving cell death. Here we show that immature CD4−8+ cells when confronted with T cell receptor ligands in vitro neither survive nor differentiate into cells which cannot be deleted, indicating that clonal elimination rather than developmental arrest is the mechanism of central tolerance of all immature T cells.
Delay in expression of a mammary tumor provirus is responsible for defective clonal deletion during postnatal period
Authors: Niimi Naoya , Tomida Shin , Ueda Minoru , Kaneda Toshio , Ando Yoshihiro , Takeuchi Makoto , Yoshikai Yasunobu , Wajjwalku Worawidh 
Published: March 2007

AbstractA gene‐encoding ligand for deletion of T cells bearing TcRVβ6 and Vβ8.1 cosegregates a new mammary tumor provirus locus, Mtv‐50 in NC mice. The sequence of the open reading frame (ORF) in the 3′ long terminal repeat (LTR) of Mtv‐50 was strikingly similar to those of Mtv‐7, Mtv‐43 and exogenous mouse mammary tumor virus (SW) with properties of minor lymphocyte stimulating antigen 1a. Consistent with previous reports, clonal deletion of mature thymocytes bearing TcRVβ6 was defective during the early postnatal period of mice carrying Mtv‐50. Appreciable levels of mRNA corresponding to common Mtv ORF and Mtv‐6 ORF were expressed in the neonatal thymus, while little, if any, mRNA corresponding to Mtv‐50 ORF was detected in the thymus at the early postnatal stage. Delay in expression of Mtv‐50 ORF during the postnatal period may be responsible for the failure of clonal deletion of Vβ6‐T cells in the early postnatal life of mice carrying Mtv‐50.
Helper effector function of human T cells stimulated by anti‐CD3 mAb can be enhanced by co‐stimulatory signals and is partially dependent on CD40‐CD40 ligand interaction
Authors: Kwekkeboom Jaap , De Rijk Diana , Kasran Ahmad , Barcy Serge , De Groot Cornelis , De Boer Mark 
Published: March 2007

AbstractIn this study we have investigated whether anti‐CD3‐induced human T cell help for immunoglobulin production could be enhanced by co‐stimulation of the T cells via other T cell surface molecules, and the contribution of CD40‐CD40 ligand interaction to the execution of T helper effector function induced by these different stimulatory signals. In a system in which irradiated tonsillar T cells were stimulated with immobilized anti‐CD3 monoclonal antibody (mAb), it was found that ligation of CD2 with a mitogenic pair of mAb considerably enhanced anti‐CD3‐induced T cell help for immunoglobulin production. Likewise, ligation of CD28 with mAb enhanced T helper activity, although to a lesser extent. Upon addition of anti‐CD28 and anti‐CD2 mAb together, an even higher immunoglobulin production was observed. This combination resulted in a four‐ to fivefold increase in immunoglobulin production as compared to cultures in which T cells were stimulated with anti‐CD3 mAb alone. The effect of ligation with B7, the natural ligand of CD28, was studied in a system which utilizes the presentation of anti‐CD3 mAb on human FcγRII‐expressing mouse fibroblasts which were co‐transfected with human B7. It appeared that B7 could stimulate help for immunoglobulin production much more efficiently than ligation of CD28 with mAb did. Physical separation of B cells from T cells led to complete abrogation of immunoglobulin production. Blocking of CD40 with specific mAb, which have no intrinsic B cell stimulatory properties, or the CD40 ligand with a soluble CD40‐human IgM fusion protein, resulted in dose‐dependent, but only partial, inhibition of T cell‐dependent immunoglobulin production with all modes of T cell activation tested. A clear correlation was found between the induction of CD40 ligand expression on the T cells by the different modes of co‐stimulation and subsequent immunoglobulin production by the B cells. It is concluded that ligation of CD28 and/or CTLA‐4, and of CD2 can generate co‐stimulatory signals for T cell help for immunoglobulin production, which was found to be only partially dependent on the CD40‐CD40 ligand interaction.
Interleukin‐3 and Bcl‐2 cooperatively inhibit etoposide‐induced apoptosis in a murine pre‐B cell line
Authors: Ascaso Rosalia , Marvel Jacqueline , Collins Mary K. L. , López‐Rivas Abelardo 
Published: March 2007

AbstractMurine bone marrow‐derived hemopoietic cells, dependent on interleukin (IL)‐3 for their growth in culture, undergo programmed cell death, or apoptosis, upon cytokine withdrawal. The topoisomerase II inhibitor etoposide causes a more rapid onset of apoptosis in the IL‐3‐dependent cell line BAF3, deprived of IL‐3. This acceleration of apoptosis by etoposide is prevented by inhibitors of RNA and protein synthesis and by the nucleases inhibitor aurintricarboxylic acid. The presence of IL‐3 or overexpression of the oncogene bcl‐2 caused a marked delay in the induction of apoptosis by etoposide, acting in a cooperative manner. The time at which the apoptotic program is irreversible is close to the induction of endonuclease activity as indicated by the effect of the delayed addition of either IL‐3 or aurintricarboxylic acid on the onset of apoptosis, suggesting the importance of endonuclease activation in the development of apoptosis in hemopoietic cells.
Absence of peripheral clonal deletion and anergy in immune responses of T cell‐reconstituted athymic mice
Authors: Williams Owen , Aroeira Luiz S. , Martínez‐A Carlos 
Published: March 2007

AbstractSuperantigens induce clonal deletion of reactive T cells in the thymus and clonal deletion and anergy in the periphery of euthymic mice. In this report we have assessed the ability of Staphylococcal enterotoxin B (SEB) to induce peripheral tolerance in nude mice reconstituted with normal, syngeneic T cells. Immunization of reconstituted nude mice with SEB resulted in lethal toxic shock in a large fraction of the animals. Such lethality was never observed in the normal donor mouse strain. Analysis of lymphokine production in response to SEB showed that reconstituted nude mice produced higher levels of interleukin‐2 and tumor necrosis factor‐α, but lower levels of interleukin‐4, than euthymic control mice. Furthermore, SEB was unable to promote either clonal elimination or induction of anergy in the SEB‐responsive peripheral T cells, despite the fact that reconstituted nude mice did produce high levels of corticosterone upon treatment with SEB. These results imply a lack of control over immune responses to superantigen in T cell‐reconstituted athymic mice.
Involvement of p21ras activation in T cell CD69 expression
Authors: d'Ambrosio Daniele , Cantrell Doreen A. , Frati Luigi , Santoni Angela , Testi Roberto 
Published: March 2007

AbstractThe involvement of p21ras in the induction of the early activation antigen CD69 was investigated in T cells. Expression of a v‐Ha‐ras coding for a constitutively active ras protein in Jurkat cells resulted in CD69 induction on the cell surface. Transfected ras was shown to be constitutively activated and functionally efficient, since it could be immunoprecipitated in the guanosine triphosphate (GTP)‐bound form and it induced transactivation of an AP‐1 consensus‐chloramphenicol acetyltransferase reporter gene. The requirement for ras activation in T cell receptor (TcR) CD3‐mediated CD69 induction was also investigated. The expression of a dominant negative c‐Ha‐ras‐N17 mutant markedly reduced the amount of GTP that could be immunoprecipitated from ras proteins after TcR/CD3 triggering in Jurkat cells, and concomitantly decreased TcR/CD3‐mediated CD69 induction. These results suggest a central role for ras in TcR/CD3‐mediated CD69 expression in T cells.
Effect of a selective protein kinase C inhibitor, Ro 31–8425, on Mac‐1 expression and adhesion of human neutrophils
Authors: Sullivan John A. , Merritt Janet E. , Budd John M. , Booth Robert F. G. , Hallam Trevor J. 
Published: March 2007

AbstractThe role of protein kinase C (PKC) in mediating up‐regulation of macrophage 1 adhesion protein (Mac‐1) and adhesion of neutrophils in response to physiological agonists is not clear. Previous studies have relied on use of phorbol esters to activate PKC directly or on results obtained with non‐selective inhibitors of protein kinases. 3‐[8‐(Aminomethyl)–6,7,8,9‐tetrahydropyridol[1,2‐a]‐indol‐10‐yl]‐4‐(1‐methyl‐3‐indolyl)‐1H‐pyrrole‐2,5‐dione hydrochloride (Ro 31–8425) is a potent and highly selective inhibitor of PKC (Bit et al. J. Med. Chem. 1993. 36: 21). In these studies Ro 31–8425 has been used to define, more definitively, the role of PKC in mediating complement fragment C5a (C5a)‐stimulated up‐regulation of Mac‐1 and adhesion of neutrophils to endothelial cells and to bovine serum albumin (BSA)‐coated plastic. Phorbol 12, 13 dibutyrate (PBu2) increased surface expression of Mac‐1 and stimulated adhesion of neutrophils to endothelial cells and to BSA‐coated plastic. This confirms previous reports that activation of PKC can stimulate these responses. The PKC inhibitor, Ro 31–8425, inhibited the PBu2‐stimulated responses, which confirms that Ro 31–8425 was effective in inhibiting PKC in these neutrophils. A more physiological agonist, C5a, also increased surface expression of Mac‐1 and adhesion of neutrophils to endothelial cells and BSA‐coated plastic. However, the responses to C5a were unaffected by Ro 31–8425. These results suggest that, although activation of PKC can promote up‐regulation of Mac‐1 and adhesion of neutrophils, this does not appear to be the physiological pathway. A non‐selective protein kinase inhibitor, staurosporine, inhibited both PBu2 and C5a‐stimulated adhesion. This suggests that a protein kinase other than PKC, possibly a tyrosine protein kinase, is likely to be involved in mediating C5a‐stimulated Mac‐1 up‐regulation and adhesion. These results emphasise the need for caution in interpreting experiments and assuming a role for PKC. Use of a potent and selective inhibitor of PKC, Ro 31–8425, provides more definitive information.
Extracellular matrix components of the mouse thymus microenvironment. IV. Modulation of thymic nurse cells by extracellular matrix ligands and receptors
Authors: Villa‐Verde DÉA Maria Serra , Machado Jussara , Lagrota‐Candido  , Vannier‐Santos Marcos Andre , Chammas Roger , Brentani Ricardo Renzo , Savino Wilson 
Published: March 2007

AbstractExtracellular matrix (ECM) proteins can influence cell migration and differentiation in a variety of cell systems. Within the thymus, these molecules are heterogeneously distributed, and their physiological role is poorly understood. This prompted us to carry out in vitro studies using the thymic nurse cell (TNC) model. We observed that fibronectin and laminin accelerate spontaneous in vitro release of thymocytes from TNC, whereas anti‐ECM antibodies exhibited a blocking effect. Similar results were obtained with anti‐ECM receptor reagents. Moreover, these antibodies abrogated in vitro reconstitution of TNC complexes and thymocyte adhesion to TNC‐derived epithelial cultures.Our results indicate that lymphocyte traffic in TNC (comprising both entrance into and exit from the epithelial structure) is affected by interactions involving extracellular matrix ligands and receptors. In this respect, the dynamic analysis of thymic nurse cell complexes should be regarded as a relevant in vitro tool for functional studies of distinct adhesion molecules in intrathymic lymphocyte traffic.