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Mature B Cells (mature + b_cell)
Selected AbstractsTolerance checkpoints in B-cell development: Johnny B goodEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 9 2009Roxane Tussiwand Abstract B-cell development up to the immature B-cell stage takes place in the bone marrow, while final maturation into mature B cells occurs in the spleen. During differentiation, the precursor and immature B cells have to pass several checkpoints, including those in which they are censored for being auto-reactive, and therefore being potentially dangerous. Numerous studies have shown that the immature B-cell stage in the bone marrow and the transitional B-cell stages in the spleen comprise distinct checkpoints at which auto-reactivity is censored. Recently, evidence has been provided that the large pre-BII stage in the bone marrow, at which the pre-BCR is expressed, is yet another B-cell tolerance checkpoint. Here, we review these findings and speculate on directions for possible further experimentation. [source] Systemic IFN-, drives kidney nephritis in B6.Sle123 miceEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 7 2008Anna-Marie Fairhurst Abstract The impact of IFN-, secretion on disease progression was assessed by comparing phenotypic changes in the lupus-prone B6.Sle1Sle2Sle3 (B6.Sle123) strain and the parental C57BL/6 (B6) congenic partner using an adenovirus (ADV) expression vector containing a recombinant IFN-, gene cassette (IFN-ADV). A comprehensive comparison of cell lineage composition and activation in young B6 and B6.Sle123 mice revealed a variety of cellular alterations in the presence and absence of systemic IFN-,. Most IFN-,-induced phenotypes were similar in B6 and B6.Sle123 mice; however, B6.Sle123 mice uniquely exhibited increased B1 and plasma cells after IFN-, exposure, although both strains had an overall loss of mature B cells in the bone marrow, spleen and periphery. Although most of the cellular effects of IFN-, were identical in both strains, severe glomerulonephritis occurred only in B6.Sle123 mice. Mice injected with IFN-ADV showed an increase in immune complex deposition in the kidney, together with an unexpected decrease in serum anti-nuclear antibody levels. In summary, the predominant impact of systemic IFN-, in this murine model is an exacerbation of mechanisms mediating end organ damage. [source] Apoptosis via the B cell antigen receptor requires Bax translocation and involves mitochondrial depolarization, cytochrome C release, and caspase-9 activationEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 7 2004Eric Eldering Abstract Various routes to apoptosis can be active during B cell development. In a model system of mature B cells, differences in caspase-3 processing have suggested that antigen receptor (BCR)-mediated apoptosis may involve a zVAD-insensitive initiator protease(s). In search of the events leading to caspase-3 activation, we now establish that both CD95- and BCR-mediated apoptosis depend on Bax activation and cytochrome C (cytC) release. Nevertheless, the timing and caspase-dependence of mitochondrial membrane depolarization differed considerably after CD95- or BCR-triggering. To delineate events subsequent to cytC release, we compared apoptosis induced via BCR triggering and via direct mitochondrial depolarization by CCCP. In both cases, partial processing of caspase-3 was observed in the presence of zVAD. By expression in 293 cells we addressed the potential of candidate initiator caspases to function in the presence of zVAD, and found that caspase-9 efficiently processed caspase-3, while caspase-2 or ,8 were inactive. Finally, retroviral expression of dominant-negative caspase-9 inhibited both CD95- and BCR-mediated apoptosis. In conclusion, we obtained no evidence for involvement of a BCR-specific protease. Instead, our data show for the first time that the BCR-signal causes Bax translocation, followed by mitochondrial depolarization, and cytC release. Subsequent caspase-9 activation can solely account for events further downstream. [source] A tolerogenic peptide down-regulates mature B cells in bone marrow of lupus-afflicted mice by inhibition of interleukin-7, leading to apoptosisIMMUNOLOGY, Issue 2 2009Hava Ben-David Summary Systemic lupus erythematosus (SLE) is an autoimmune disease mediated by T and B cells. It is characterized by a variety of autoantibodies and systemic clinical manifestations. A tolerogenic peptide, designated hCDR1, ameliorated the serological and clinical manifestations of SLE in both spontaneous and induced models of lupus. In the present study, we evaluated the status of mature B cells in the bone marrow (BM) of SLE-afflicted mice, and determined the effect of treatment with the tolerogenic peptide hCDR1 on these cells. We demonstrate herein that mature B cells of the BM of SLE-afflicted (New Zealand Black × New Zealand White)F1 mice were largely expanded, and that treatment with hCDR1 down-regulated this population. Moreover, treatment with hCDR1 inhibited the expression of the pathogenic cytokines [interferon-, and interleukin (IL)-10], whereas it up-regulated the expression of transforming growth factor-, in the BM. Treatment with hCDR1 up-regulated the rates of apoptosis of mature B cells. The latter was associated with inhibited expression of the survival Bcl-xL gene and of IL-7 by BM cells. Furthermore, the addition of recombinant IL-7 abrogated the suppressive effects of hCDR1 on Bcl-xL in the BM cells and resulted in elevated levels of apoptosis. Hence, the down-regulated production of IL-7 contributes to the hCDR1-mediated apoptosis of mature B cells in the BM of SLE-afflicted mice. [source] The riddle of the dual expression of IgM and IgDIMMUNOLOGY, Issue 4 2006Roland Geisberger Summary Signalling through the B cell antigen receptor (BCR) is required for peripheral B lymphocyte maturation, maintenance, activation and silencing. In mature B cells, the antigen receptor normally consists of two isotypes, membrane IgM and IgD (mIgM, mIgD). Although the signals initiated from both isotypes differ in kinetics and intensity, in vivo, the BCR of either isotype seems to be able to compensate for the loss of the other, reflected by the mild phenotypes of mice deficient for mIgM or mIgD. Thus, it is still unclear why mature B cells need expression of mIgD in addition to mIgM. In the current review we suggest that the view that IgD has a simpIy definable function centred around the basic signalling function should be replaced by the assumption that IgD fine tunes humoral responses, modulates B cell selection and homeostasis and thus shapes the B cell repertoire, defining IgD to be a key modulator of the humoral immune response. [source] B-cell dysfunction and depletion using mycophenolate mofetil in a pediatric combined liver and kidney graft recipientPEDIATRIC TRANSPLANTATION, Issue 1 2001R. Ganschow Abstract: The use of mycophenolate mofetil (MMF) in combination with cyclosporin A (CsA) and steroids is well established after kidney transplantation (Tx) in children. A 9-yr-old girl with primary hyperoxaluria type 1 and systemic oxalosis underwent a combined kidney and liver Tx at our institution. The post-operative immunosuppression consisted of CsA, prednisolone, and MMF. Four weeks post-transplant the girl suffered from a severe urinary tract infection caused by Pseudomonas aeruginosa, when the serum immunoglobulin G (IgG) concentration was found to be critically low (< 1.53 g/L). Additionally, there was an isolated B-cell depletion (240/µL) at that time. In the following course, the B-cell count was significantly diminished until the MMF was stopped 13 weeks post-transplant. As a result of the very low serum IgG concentration, intravenous immunoglobulin (IVIG) substitution was necessary. There was no significant loss of immunoglobulins in the ascites and urine and no other medication with possible side-effects on B cells was given. We suggest that MMF can lead to suppressed IgG production by B cells and can cause a defective differentiation into mature B cells. In vitro studies demonstrated these effects of MMF on B cells, but no in vivo cases of this phenomenon have been reported. B-cell counts and serum IgG concentrations returned to normal values after discontinuing the MMF. As we can assume that the observed B-cell dysfunction and depletion were MMF related, we suggest that serum IgG concentrations should be monitored when MMF is used after solid-organ Tx. [source] Differential expression of interleukin-17 family cytokines in intact and complicated human atherosclerotic plaques,THE JOURNAL OF PATHOLOGY, Issue 4 2010Onno J de Boer Abstract In addition to the classical TH1 and TH2 cytokines, members of the recently identified IL-17 cytokine family play an important role in regulating cellular and humoral immune responses. At present nothing is known about the role of these cytokines in atherosclerosis. Expression of IL-17A, -E and -F was investigated in atherosclerotic tissue by rtPCR and immunohistochemistry. IL-17E and its receptor were further studied in cultured smooth muscle cells and endothelial cells, using rtPCR and western blot. rtPCR showed that IL-17A, -E and -F were expressed in the majority of plaques under investigation. IL-17A/F was expressed by mast cells in all stages of plaque development. IL-17A/F+ neutrophils were always observed in complicated plaques, but hardly in intact lesions. IL-17A/F+ Tcells (,TH17') were never observed. IL-17E was expressed by smooth muscle cells and endothelial cells in both normal and atherosclerotic arteries, and in advanced plaques also extensively by mature B cells. Cultured smooth muscle cells and endothelial cells were found to express both IL-17E and its functional receptor (IL-17RB). The constitutive expression of IL-17E by resident plaque cells, and the additional presence of IL-17E+ B cells and IL-17A/F+ neutrophils in advanced and complicated plaques indicates a complex contribution of IL-17 family cytokines in human atherosclerosis, depending on the stage and activity of the disease. Copyright © 2009 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [source] Histopathology and Immunophenotype of the Spleen During Acute Antibody-Mediated RejectionAMERICAN JOURNAL OF TRANSPLANTATION, Issue 5 2010B. Kaplan Splenectomy has been reported to have a beneficial effect in treating Acute antibody-mediated rejection (ABMR). This reason for this often rapid and profound beneficial effect is not readily apparent from what is known about normal splenic immunoarchitecture. While the spleen is rich in mature B cells, it has not been noted to be a repository for direct antibody-secreting cells. We present a case of a Native American female who received a renal transplant and developed a severe episode of ABMR. The patient was initially refractory to both plasmapheresis and IVIG. The patient underwent an emergent splenectomy with almost immediate improvement in her renal function and a rapid drop in her DR51 antibodies. Immunohistochemical stains of the spleen demonstrated abundant clusters of CD138+ plasma cells (>10% CD138 cells as opposed to 1% CD138 cells as seen in traumatic controls). Though this is a single case, these findings offer a rationale for the rapid ameliorative effect of splenectomy in cases of antibody rejection. It is possible that the spleen during times of excessive antigenic stress may rapidly turn over B cells to active antibody-secreting cells or serve as a reservoir for these cells produced at other sites. [source] | ||||||||||||||||||||||