bluuebunny/crossref_metadata_2025_split huggingface dataset:
Activation and hapten inhibition of mast cells sensitized with monoclonal IgE anti‐penicillin antibodies: evidence for two‐site recognition of the penicillin derived determinant
Authors: Fernandez Mercedes , Warbrick E. Victoria , Blanca Miguel , Coleman John W. 
Published: March 2007

AbstractWe utilized an in vitro mast cell activation assay and hapten inhibition of mediator release to characterize the fine specificity of two IgE anti‐penicillin monoclonal antibodies (mAb). Cultured mouse mast cells were passively sensitized with IgE mAb anti‐benzylpenicillin (BP) or anti‐amoxicillin (AX) and challenged with a range of penicillin‐human serum albumin (HSA) conjugates. Mast cells sensitized with IgE anti‐BP degranulated in response to BP‐HSA, but not to AX‐HSA or ampicillin(AMP)‐HSA, whereas mast cells sensitized with IgE anti‐AX responded to AX‐HSA but not to BP‐HSA or AMP‐HSA. Because BP, AX and AMP differ chemically only in the structure of their side chain, these results show that this part of the drug molecule is essential for recognition by IgE antibody. Unexpectedly, although IgE‐sensitized mast cells responded to only one penicillin in protein‐conjugated form, antigen‐induced degranulation was inhibited by the monomeric derivative of more than one penicillin. Furthermore, antigen activation of IgE‐sensitized cells was inhibited, although less potently, by haptens representative of the specific penicillin side chain or the binuclear portion of the drug molecule. These patterns of recognition and hapten inhibition were also seen in solid‐phase enzyme‐linked immunosorbent assay (ELISA), although all haptenic inhibitors were approximately 100 times less potent in the ELISA compared to the mast cell assay. To explain these findings we propose a model in which IgE binding to penicillin‐protein antigen is dependent on recognition of two distinct epitopes on the drug molecule: the first comprising the side chain, and the second comprising the binuclear portion plus the proximal region of the side chain. This two‐site hypothesis provides a generally applicable model of antibody recognition of penicillins and provides a rational basis for understanding the specificity and cross‐reactivity of IgE‐mediated allergic reactions to penicillins.
Involvement of NAK‐1, the human nur77 homologue, in surface IgM‐mediated apoptosis in Burkitt lymphoma cell line BL41
Authors: Mapara Markus Y. , Weinmann Pamela , Bommert Kurt , Daniel Peter T. , Bargou Ralf , Dörken Bernd 
Published: March 2007

AbstractThe induction of apoptosis via surface IgM (sIgM) in immature B cells requires de novo transcription. To investigate the regulation of activation‐induced cell death (AICD) in B cells we used a cell line model consisting of an Epstein‐Barr virus‐negative Burkitt lymphoma cell line (BL41), which is highly sensitive, and a subclone which is resistant to sIgM‐mediated apoptosis (BL41/B5). Resistance in this cell line was not due to down‐regulation of sIgM or functional impairment in signal transduction of the surface Ig complex. The zinc finger transcription factor nur77 has been implicated to play an important role in CD3‐mediated apoptosis in murine T cells. We were able to demonstrate that surface IgM ligation and subsequent apoptosis in BL41 cells is associated with a concomitant induction of NAK‐1, the human nur77 homologue. Induction of NAK‐1 mRNA and DNA binding activity in the nucleus could be readily observed by means of Northern blot and electrophoretic mobility shift assay, respectively. In contrast, the resistant clone BL41/B5 did not show any NAK‐1 expression upon stimulation. This suggests a role for NAK‐1 in sIgM‐mediated apoptosis of immature B cells.
Evidence for Th2 cell‐mediated suppression of antibody responses in transgenic, beef insulin‐tolerant mice
Authors: Teng Yen‐Tung , Gorczynski Reginald M. , Iwasaki Shinji , Williams Douglas B. , Hozumi Nobumichi 
Published: March 2007

AbstractClonal deletion, anergy and suppression have all been considered mechanisms of immunological tolerance. Although adoptive transfer of immunosuppression has been shown to occur in the periphery, particularly for transplantation tolerance, it has proven difficult to characterize this phenomenon further, due to the lack of suppressor T cell clones. To characterize tolerance towards a physiological soluble antigen, we constructed beef insulin (BI) transgenic (Tg) BALB/c (H‐2d) mice, in which the BI transgene is expressed in pancreatic β cells. These Tg mice were tolerant to BI immunization at the level of both humoral and cell‐mediated immune responses. Adoptive transfer of splenocytes from Tg mice into normal syngeneic BALB/c mice demonstrated that the reduction in antibody production is regulated by transferred T cells. The cytokine profile of T cell clones obtained after selection in vitro demonstrated dominant Th1 clones from normal non‐Tg mice and dominant Th2 clones from Tg mice. Some Th2 clones (CD4+) from Tg mice produced significant suppression of antibody production after adoptive transfer into normal syngeneic BALB/c mice. These data confirm the existence of Th2 regulatory T cells in vivo in a model of peripheral tolerance to a physiological soluble antigen as a potential mechanism for self tolerance.
Murine lupus in MRL/lpr mice lacking CD4 or CD8 T cells
Authors: Koh Dow‐Rhoon , Ho Alexandra , Rahemtulla Amin , Fung‐Leung Wai‐Ping , Griesser Henrik , Mak Tak‐Wah 
Published: March 2007

AbstractMRL/lpr mice develop a systemic autoimmune disease similar to systemic lupus erythematosus in humans. The mice show progressive lymphadenopathy due to the accumulation of an unusual population of CD4−8−(DN) B220+ αβ+ T cells. We bred MRL/lpr mice with mice lacking CD4+ or CD8+ T cells by gene targeting via homologous recombination in embryonal stem cells to determine the roles of these cells in the autoimmune disease. No difference in survival or autoantibody levels was noted between CD8‐/‐ lpr and littermate controls. Interestingly, these CD8‐/‐ lpr mice have a reduced level of B220+ DN T cells despite the fact that the degree of lymphadenopathy was unaltered. CD4‐/‐ lpr mice had a diminished autoimmune disease with a reduction in autoantibody production and skin vasculitits, and increased survival compared to littermate controls. However, CD4‐/‐ lpr mice had an enhanced splenomegaly that developed massively by 16–20 weeks of age (5 to 8 greater than lpr control mice) due to the accumulation of DN B220+ T cells. In addition, there were no differences in peripheral lymph node enlargement, although the proportion of DN B220+ T cells was about twofold higher in the CD4‐/‐ lpr mice. These cells were phenotypically identical to the DN population in control lpr mice, indicating that the accumulating DN T cells can be dissociated from the autoimmune disease in these mice. Collectively, our results reveal that the autoimmune disease is dependent on CD4+, but not CD8+ T cells, and that many of the B220+ DN T cells traverse a CD8 developmental pathway.
Extensive allelic sequence variation in the J region of the human immunoglobulin heavy chain gene locus
Authors: Mattila Petri S. , Schugk Jan , Wu Hongyan , Mäkelä Olli 
Published: March 2007

AbstractDuring the initial stages of B lymphocyte differentiation heavy chain variable (VH), diversity (DH) and joining (JH) gene segments recombine to form a functional heavy chain variable region (VDJ) gene. Evidence for genetic polymorphism of the human JH gene segments has been obtained from mature rearranged VDJ sequences. We conducted an analysis of the published rearranged JH gene sequences and found that the JH alleles present in the two published germ‐line JH region sequences were rare (approx. 2%) in the rearranged sequences. As an attempt to explain this discrepancy a 2.5‐kb strech of DNA containing all the six heavy chain JH region genes and the most 3' DH gene segment, DHQ52, was amplified by the polymerase chain reaction from 39 individuals and analyzed for restriction fragment length polymorphism. Five new JH region haplotypes were found and sequenced. These new haplotypes contained the coding segment alleles that were frequent in antibody genes. Surprisingly, a high number of interallelic differencies in the non‐coding sequence was found between the new and the two previously published haplotypes implying that the haplotypes had been separated early in evolution. In this respect the JH locus resembles HLA loci.
Evidence that CD4+, but not CD8+ T cells are responsible for murine interleukin‐2‐deficient colitis
Authors: Simpson Stephen J. , Mizoguchi Emiko , Allen Deborah , Bhan Atul K. , Terhorst Cox 
Published: March 2007

AbstractMice deficient in interleukin‐2 production (IL‐2null mice) develop colonic inflammation closely resembling ulcerative colitis in humans. Although this disease is marked by substantial infiltration of the colon by CD8+ and CD4+ T lymphocytes, no function has yet been assigned to these T cell subsets in the development of colitis in the IL‐2null mouse. For the present study, we investigated the involvement of T lymphocytes in the onset of colitis in IL‐2null mice, and examined the possible role played by cytotoxic T cells. Both lamina propria lymphocytes (LPL) and intraepithelial lymphocytes (IEL) of the colon of IL‐2null mice were potently cytotoxic ex vivo in short‐term redirected cytotoxic lymphocyte (CTL) assays. In contrast, colonic T cells of wild‐type animals showed little or no constitutive cytotoxic T cell activity. Colonic CTL were detectable prior to the appearance of disease in IL‐2null animals and CTL activity was confined to the TcRαβ, rather than to the TcRγδ IEL subset. IL‐2null animals crossed with major histocompatibility complex class I‐deficient mice [IL‐2null × β2 microglobulin (β2mnull] mice also developed colitis, which appeared even earlier than in most IL‐2null mice. These findings suggest that neither CD8+ IEL nor LPL were causal in the onset of colitis in IL‐2null animals. In IL‐2null × β2mnull mice, an ulcerative colitis‐like disease was evident from histological studies and immunohistological staining which showed very large numbers of CD4+ lymphocytes within the intestinal mucosa. Significant ex vivo killing by CD4+ T cells was observed in IL‐2null × β2mnull animals, although this required an extended incubation time compared to colonic CD8+ T cells. Peripheral as well as colonic CD4+ T cells in IL‐2null and IL‐2null × β2mnull animals, were activated as judged by their cell surface phenotype (CD45RBlo, L‐selectinlo and CD69+). In light of these findings, we propose that infiltrating CD4+, but not CD8+ T cells are central to the inflammation observed in the intestinal mucosa in IL‐2null colitis.
Cytotoxic T lymphocytes raised against a subdominant epitope offered as a synthetic peptide eradicate human papillomavirus type 16‐induced tumors
Authors: Feltkamp Mariet C. W. , Vreugdenhil Gienke R. , Vierboom Michel P. M. , Ras Elisabeth , van der Burg Sjoerd H. , Schegget Jan Ter , Melief Cornelis J. M. , Kast W. Martin 
Published: March 2007

AbstractPreviously, we have shown that immunization with human papillomavirus (HPV) type 16‐derived cytotoxic T lymphocyte (CTL) epitope E7 49–57 (RAHYNIVTF) renders C57BL/6 mice insensitive to tumors formed by HPV16‐transformed cells. In this study, we provide evidence that E7 49–57 is expressed as a subdominant CTL epitope on HPV16‐transformed C57BL/6 cells. Using acid peptide elution, it is shown that HPV16‐transformed cells express another CTL epitope, besides E7 49‐57, which appears to be dominant. We demonstrate that a CTL line raised against the subdominant CTL epitope, offered as synthetic peptide E7 49–57, eradicates established HPV16‐induced tumors in mice. Our data show that synthetic peptide‐induced CTL can be applied successfully in vivo against (virus‐induced) tumor, and emphasize that subdominant CTL epitopes are useful targets for immunotherapy. Furthermore, it is illustrated for the first time that HPV16‐specific CTL interfere directly with HPV16‐induced tumors.
T cell development and repertoire of mice expressing a single T cell receptor α chain
Authors: Brändle Daniel , Brduscha‐Riem Karin , Hayday Adrian C. , Owen Michael J. , Hengartner Hans , Pircher Hanspeter 
Published: March 2007

AbstractWe examined T cell development and T cell repertoire in transgenic mice expressing a single T cell receptor (TCR) α chain derived from the H‐2Db ‐lymphocytic choriomeningitis virus (LCMV)‐specific cytolytic T lymphocyte (CTL) clone P14. To generate these α P14 mice, mice transgenic for the P14 TCR α chain were backcrossed to TCR α‐deficient mice. Thymi from α P14 mice exhibited a marked decrease of mature CD4+8− and CD8+4− single‐positive thymocytes comparable to thymi from TCR α‐deficient mice. Correspondingly, the number of peripheral T cells was reduced in the CD4 (tenfold) and in the CD8 (twofold) subsets when compared to normal mice. T cells from α P14 mice generated a primary anti‐LCMV CTL response when stimulated in vitro with LCMV in contrast to normal mice which require priming in vivo; elimination of LCMV in vivo was, however, not improved. Flow cytometric analysis of T cells with Vβ‐specific antibodies showed a diverse endogenous TCR Vβ repertoire. Functional analysis of the T cell repertoire, however, revealed a strongly reduced (30‐fold) allogeneic and the absence of a vesicular stomatitis virus‐specific CTL response and an impaired ability to provide T cell help for antibody isotype switching. Thus, T cell selection in the thymus was impaired and the T cell repertoire was limited in mice expressing only one type of TCR α chain.
Comparison of CD28‐B7.1 and B7.2 functional interaction in resting human T cells: Phosphatidylinositol 3‐kinase association to CD28 and cytokine production
Authors: Ghiotto‐Ragueneau Marguerite , Battifora Michela , Truneh Alemsedeg , Waterfield Michael D. , Olive Daniel 
Published: March 2007

AbstractCD28 is a 44‐kDa homodimer present on T cells providing an important costimulatory signal for T cell proliferation, cytokine production and cytokine receptor expression. CD28 activation is mediated by interaction with its counter‐receptors, B7.1/CD80 and B7.2/B70/CD86. The biochemical basis of these costimulatory signals are still poorly understood, particularly in resting T cells. However, various biochemical pathways such as tyrosine phosphorylation, phospholipase C, sphingomyelinase and phosphatidylinositol 3‐kinase (PI3‐K) activation have been reported to play a role in CD28 signaling in tumor T cell lines and CD28‐transfected cells or pre‐activated T cells. In addition, recent reports propose that CD28‐B7.1 and B7.2 interaction could be involved in the production of Th1 and Th2 cytokines, respectively, but the putative biochemical basis for these different functions is still unknown. We have analyzed the functional and molecular consequences of CD28 activation by B7.1 and B7.2 in human resting T cells. We demonstrate in this report that both CD28‐B7.1 and CD28‐B7.2 interactions induce the association of PI3‐K to CD28 in the CD4 subpopulation, whereas it was barely detectable in CD8 cells. This association involves the binding of the src homology domain 2 (SH2) of p85 to tyrosine‐phosphorylated CD28 and does not require pre‐activation by CD3‐T cell receptor. Worthmannin, a specific inhibitor of PI3‐K enzymatic activity within the nanomolar range also inhibits the interleukin‐2 production induced by costimulation mediated by either the B7.1‐ and B7.2‐transfected cells or CD28 monoclonal antibodies. The only slight difference between B7.1 and B7.2 costimulation is the IC50 of wortmannin being 25 and 110 nM, respectively, which could suggest differences in their activation of the T cell PI3‐K.
Modulation of expression of the anti‐inflammatory cytokines interleukin‐13 and interleukin‐10 by interleukin‐3
Authors: Marietta Eric V. , Chen Yiyou , Weis John H. 
Published: March 2007

AbstractInterleukin (IL)‐4, IL‐10 and IL‐13 are cytokines with potent anti‐inflammatory activities. Prevention of pathological inflammation at mucosal surfaces appears to be due, in part, to the presence of these cytokines. One potential source for these cytokines is the mast cell which resides at mucosal surfaces. Demonstrated in this report are the findings that bone marrow‐derived mucosal‐like mast cells constitutively expressed IL‐13 whereas bone marrow‐derived connective tissue‐like mast cells demonstrated IL‐13 transcription only after FcεRI‐mediated activation or the addition of exogenous IL‐3. A similar pattern of expression of IL‐10 by these mast cell types was also evident and matches that of IL‐4 previously reported. Intracellular cytokine staining indicated that IL‐10 protein is constitutively expressed by the bone marrow‐derived mucosal‐like mast cells but is only evident in the bone marrow‐derived connective tissue‐like mast cells after induction with IL‐3. The increase of IL‐13 and IL‐10 transcripts in the connective tissue‐like mast cells following IL‐3 treatment is not mast cell specific, in that splenic and bone marrow cells also demonstrated the same phenomenon. These data suggest that mucosal mast cells may have a constitutive repertoire of Th2 cytokines with potential anti‐inflammatory activity, while connective tissue mast cells may not. However, production of such cytokines can be induced in the connective tissue mast cell and other cell types of the immune response by the addition of IL‐3.
Anti‐CD5 extends the proliferative response of human CD5+ B cells activated with anti‐IgM and interleukin‐2
Authors: Jamin Christophe , Le Corre Rozenn , Lydyard Peter M. , Youinou Pierre 
Published: March 2007

AbstractThe CD5 T cell glycoprotein which is expressed by a subset of B cells has been shown to be involved in T cell activation and proliferation. No similar studies, to date, have addressed the role of CD5 on the B cell subset. CD5+ and CD5− B cells were sorted and stimulated with anti‐CD5 monoclonal antibody (mAb) in vitro. The activation and proliferative responses of these two populations, as measured by analysis of proliferation marker, did not differ following anti‐μ and interleukin (IL)‐2 stimulation. The addition of anti‐CD5 did not change the responsiveness of such activated CD5+ B cells but resulted in a decrease in CD25 expression. Pre‐activation of B cells with phorbol 12‐myristate 13‐acetate, which increased CD5 expression, failed to alter the proliferative response of CD5+ B cells to anti‐μ and IL‐2 with or without addition of anti‐CD5 mAb. Anti‐μ and IL‐2 treatment of CD5+ cells resulted in optimal proliferation measured at day 3 which decreased by day 6. However, addition of anti‐CD5 mAb at day 3 prevented this decline in proliferative response. This dose‐dependent effect was observed only when the anti‐CD5 mAb was presented to the B cells in cross‐linked form. Co‐stimulation of CD5 did not lower the threshold of antigen to which the B cells responded. Taken together, these data support a functional role for CD5 on B cells acting as an accessory signal, following their primary activation through the B cell receptor complex and highlight differences in the role of CD5 associated with the T cell receptor complex.
Proximity relationships between the type I receptor for Fcεe (FcεeRI) and the mast cell function‐associated antigen (MAFA) studied by donor photobleaching fluorescence resonance energy transfer microscopy
Authors: Jürgens Ludger , Arndt‐Jovin Donna , Pecht Israel , Jovin Thomas M. 
Published: March 2007

AbstractClustering of the mast cell function‐associated antigen (MAFA) on the surface of rat mucosal type mast cells line 2H3 (RBL‐2H3) leads to suppression of the secretory response induced by the type I Fcεe receptor (FcεeRI). In order to establish a possible association between MAFA and FcεeRI we measured fluorescence resonance energy transfer (FRET) between the MAFA‐specific monoclonal antibody (mAb) G63 and FcεeRI‐bound ligands as well as between FcεeRI‐bound ligands themselves using the donor photobleaching FRET (pbFRET) technique. Average FRET efficiencies between 6 and 9% were determined after low‐temperature incubation with fluorescent dye conjugated mAb G63 bound to MAFA (donor) and IgE bound to FcεeRI (acceptor) on RBL‐2H3 cells. Subsequent cross‐linking of IgE by a polyvalent antigen caused no change in FRET efficiencies. These results suggest that the MAFA is located in the vicinity of the FcεeRI on resting cells, and that clustering of the FcεeRI leads to no significant change in the proximity of the two molecular species. In view of the sequence motif identified in the cytosolic tail of the MAFA and the observed changes in its phosphorylation upon antigen stimulation (Guthmann et al., Proc. Natl. Acad. Sci. USA 1995, 92: 9397–9401), the present study suggests that the secretory response inhibition by MAFA interferes with the signal transduction cascade initiated via the FcεeRI. An additional finding was that clustering of the FcεeRI by antigen showed a clear increase in the efficiency of FRET between FcεeRI‐bound IgE molecules conjugated with fluorescent donor and acceptor.
Expression and function of Fas antigen on activated murine B cells
Authors: Wang Jiyang , Taniuchi Ichiro , Maekawa Yoichi , Howard Maureen , Cooper Max D. , Watanabe Takeshi 
Published: March 2007

AbstractWe have studied the expression and function of Fas antigen on murine B lymphocytes. While Fas was present on only a few B cells in the bone marrow, spleen, lymph node or peripheral blood, its expression could be strongly up‐regulated by stimulation with soluble CD40 ligand (CD40L). Treatment with anti‐IgM and interleukin‐4 (IL‐4) alone did not induce significant Fas expression but enhanced CD40L‐mediated up‐regulation of Fas expression. The T cell‐derived signal via CD40 is therefore a potent inducer of Fas expression by B lymphocytes. The sensitivity to Fas‐mediated apoptosis was found to depend on the duration of B cell activation. B cells activated for 1 day were resistant to Fas‐mediated cell death, whereas B cells activated for 3 days were relatively sensitive. Interestingly, different sensitivity to Fas‐mediated death signal was observed in 2‐day activated B cells. It was found that B cells stimulated with CD40 L alone were more sensitive to Fas‐mediated apoptosis than were cells stimulated with CD40L plus anti‐IgM or IL‐4, and in particular, the combination of the two. The greater sensitivity exhibited by B cells stimulated with CD40L alone seems to be related to limited activation of these cells in the absence of additional stimulation. Co‐stimulation of B cells in the presence of CD40L and anti‐Fas antibody resulted initially in activation of B lymphocytes, as reflected by the expression of activation markers and cell growth, but this was followed by growth inhibition and cell death. The data demonstrate that the B cell response can be regulated positively and negatively by signaling through CD40 and Fas antigens, respectively.