scholarly journals T cell regulation of B cell activation. T cells independently regulate the responses mediated by distinct B cell subpopulations.

1982 ◽  
Vol 155 (5) ◽  
pp. 1267-1276 ◽  
Author(s):  
Y Asano ◽  
R J Hodes

The present studies have been carried out to characterize the regulatory influences acting upon defined pathways of T cell-dependent B cell activation. In these studies, it was demonstrated that high concentrations of free carrier strongly inhibited the MHC-restricted in vitro T cell-dependent antibody responses of primed Lyb-5- B cells to the corresponding carrier-hapten conjugate. In contrast, these same concentrations of free carrier failed to inhibit the T cell dependent responses of Lyb-5+ B cells to the same antigen. The inhibition of Lyb-5- B cell responses by free carrier was shown to result from active suppression mediated by carrier-specific primed Lyt-1+2- T cells and to require the additional participation of unprimed Lyt-1-2+ T cells. The activation of this suppression was antigen-specific, but suppression once activated was antigen nonspecific in its effect. These findings thus demonstrate that distinct pathways of B cell activation can be independently regulated by T suppressor network influences, and that these pathways therefore constitute potentially independent components of the immune response to a given antigenic stimulus.

2003 ◽  
Vol 197 (2) ◽  
pp. 195-206 ◽  
Author(s):  
Simon Fillatreau ◽  
David Gray

We investigated the mechanism of CD4 T cell accumulation in B cell follicles after immunization. Follicular T cell numbers were correlated with the number of B cells, indicating B cell control of the niche that T cells occupy. Despite this, we found no role for B cells in the follicular migration of T cells. Instead, T cells are induced to migrate into B cell follicles entirely as a result of interaction with dendritic cells (DCs). Migration relies on CD40-dependent maturation of DCs, as it did not occur in CD40-deficient mice but was reconstituted with CD40+ DCs. Restoration was not achieved by the activation of DCs with bacterial activators (e.g., lipopolysaccharide, CpG), but was by the injection of OX40L–huIgG1 fusion protein. Crucially, the up-regulation of OX40L (on antigen-presenting cells) and CXCR-5 (on T cells) are CD40-dependent events and we show that T cells do not migrate to follicles in immunized OX40-deficient mice.


1984 ◽  
Vol 159 (3) ◽  
pp. 881-905 ◽  
Author(s):  
J D Ashwell ◽  
A L DeFranco ◽  
W E Paul ◽  
R H Schwartz

In this report we have examined the ability of small resting B cells to act as antigen-presenting cells (APC) to antigen-specific MHC-restricted T cells as assessed by either T cell proliferation or T cell-dependent B cell stimulation. We found that 10 of 14 in vitro antigen-specific MHC-restricted T cell clones and lines and three of four T cell hybridomas could be induced to either proliferate or secrete IL-2 in the presence of lightly irradiated (1,000 rads) purified B cells and the appropriate foreign antigen. All T cell lines and hybridomas were stimulated to proliferate or make IL-2 by macrophage- and dendritic cell-enriched populations and all T cells tested except one hybridoma caused B cell activation when stimulated with B cells as APC. Furthermore, lightly irradiated, highly purified syngeneic B cells were as potent a source of APC for inducing B cell activation as were low density dendritic and macrophage-enriched cells. Lymph node T cells freshly taken from antigen-primed animals were also found to proliferate when cultured with purified B cells and the appropriate antigen. Thus, small resting B cells can function as APC to a variety of T cells. This APC function was easily measured when the cells were irradiated with 1,000 rads, but was greatly diminished or absent when they were irradiated with 3,300 rads. Thus, the failure of some other laboratories to observe this phenomenon may be the result of the relative radiosensitivity of the antigen-presenting function of the B cells. In addition, this radiosensitivity allowed us to easily distinguish B cell antigen presentation from presentation by the dendritic cell and macrophage, as the latter was resistant to 3,300 rads. Finally, one T cell clone that failed to proliferate when B cells were used as APC was able to recruit allogeneic B cells to proliferate in the presence of syngeneic B cells and the appropriate antigen. This result suggests that there are at least two distinct pathways of activation in T cells, one that leads to T cell proliferation and one that leads to the secretion of B cell recruitment factor(s).


mBio ◽  
2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Tyler C. Moore ◽  
Ronald J. Messer ◽  
Lorena M. Gonzaga ◽  
Jennifer M. Mather ◽  
Aaron B. Carmody ◽  
...  

ABSTRACTFriend virus (FV) is a naturally occurring mouse retrovirus that infects dividing cells of the hematopoietic lineage, including antigen-presenting cells (APCs). The infection of APCs by viruses often induces their dysfunction, and it has been shown that FV infection reduces the ability of dendritic cells (DCs) to prime critical CD8+T cell responses. Nonetheless, mice mount vigorous CD8+T cell responses, so we investigated whether B cells might serve as alternative APCs during FV infection. Directex vivoanalysis of B cells from FV-infected mice revealed that infected but not uninfected B cells upregulated expression of the costimulatory molecules CD80, CD86, and CD40, as well as major histocompatibility complex class II (MHC-II) molecules. Furthermore,in vitrostudies showed that, compared to uninfected B cells from the same mice, the FV-infected B cells had significantly enhanced APC function, as measured by their capacity to prime CD8+T cell activation and proliferation. Thus, in contrast to DCs, infection of B cells with FV enhanced their APC capacity and ability to stimulate the CD8+T cell responses essential for virus control. FV infections also induce the activation and expansion of regulatory T cells (Tregs), so it was of interest to determine the impact of Tregs on B cell activation. The upregulation of costimulatory molecule expression and APC function of B cells was even more strongly enhanced byin vivodepletion of regulatory T cells than infection. Thus, Tregs exert potent homeostatic suppression of B cell activation that is partially overcome by FV infection.IMPORTANCEThe primary role of B cells in immunity is considered the production of pathogen-specific antibodies, but another, less-well-studied, function of B cells is to present foreign antigens to T cells to stimulate their activation and proliferation. Dendritic cells (DCs) are considered the most important antigen-presenting cells (APCs) for CD8+T cells, but DCs lose APC function when infected with Friend virus (FV), a model retrovirus of mice. Interestingly, B cells were better able to stimulate CD8+T cell responses when they were infected with FV. We also found that the activation status of B cells under homeostatic conditions was potently modulated by regulatory T cells. This study illustrates an important link between B cell and T cell responses and illustrates an additional mechanism by which regulatory T cells suppress critical T cell responses during viral infections.


Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4692-4692
Author(s):  
Mauro Di Ianni ◽  
Lorenzo Moretti ◽  
Beatrice Del Papa ◽  
Maria De Ioanni ◽  
Adelmo Terenzi ◽  
...  

Abstract As Chronic Lymphocytic Leukemia (CLL) is associated with several defects in the T cell compartment, the impact of tumour burden on the autologous immune system was studied. Gene expression profiles (using Applied Biosystem Human Genome Microarray) identified 237 genes with significantly increased expression and 221 genes with significantly decreased expression (p<0.05) in CD3+ cells from CLL patients compared with healthy donors. Panther software analysis identified 34/237 upregulated genes and 26/221 downregulated genes that were involved in specific pathways, mainly cell differentiation and proliferation, survival, apoptosis, cytoskeleton formation, vesicle trafficking and T cell activation. The 26 dowregulated genes included Zap70, a member of the syk family protein tyrosine kinase, which is involved in T-cell activation. Zap-70 results were validated by mRNA quantification by RT-PCR (−1.77 fold in comparison with healthy controls) and by flow-cytometric analysis (Mean Intensity Fluorescence=33±12 vs 80±23.62 in controls, p<0.05). To test the hypothesis that activation with OKT3 /IL-2 could bypass these T cell deficiencies, activated T cells from 20 patients with CLL were tested in vitro for cytotoxicity (using the 51chromium release assay) against mutated and unmutated (according to IgVH mutational status) autologous B cells, DAUDI, K562 and P815 cell lines. After 10 days’ culture, the T cell count remained unchanged; CD8 cells expanded more than CD4; TCR spectratyping analysis indicated no differences in TCR repertoires. Activation restored the ZAP-70 mRNA (+1.67 fold). The 51chromium release cytotoxicity assay showed an index > 30% in 5/20 patients. The other 15 were partially cytotoxic against P815, K562 and Daudi. Cell line analysis in all 20 confirmed prevalently T cell-mediated cytotoxicity and poor NK/LAK activity. Cytotoxicity did not correlate with B cell mutational status. We tested the cytotoxic activity of autologous activated T cells in NOD/SCID mice co-transplanted with leukaemic B cells. Only activated T cells exerting cytotoxicity vs autologous B-cell CLL prevent CLL in human-mouse chimera, as confirmed by PCR and FACS analysis which visualised only CD3+ cells. In conclusion, in patients with CLL, activating autologous T cells with OKT3 /IL-2 bypasses, at least in part, the T cell immunological deficiencies. These in vitro and in vivo findings might serve to throw light on new mechanisms that could be exploited in immunotherapy designed to exert disease control.


2004 ◽  
Vol 200 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Christopher M. Snyder ◽  
Katja Aviszus ◽  
Ryan A. Heiser ◽  
Daniel R. Tonkin ◽  
Amanda M. Guth ◽  
...  

Antibody diversity creates an immunoregulatory challenge for T cells that must cooperate with B cells, yet discriminate between self and nonself. To examine the consequences of T cell reactions to the B cell receptor (BCR), we generated a transgenic (Tg) line of mice expressing a T cell receptor (TCR) specific for a κ variable region peptide in monoclonal antibody (mAb) 36-71. The κ epitope was originally generated by a pair of somatic mutations that arose naturally during an immune response. By crossing this TCR Tg mouse with mice expressing the κ chain of mAb 36-71, we found that κ-specific T cells were centrally deleted in thymi of progeny that inherited the κTg. Maternally derived κTg antibody also induced central deletion. In marked contrast, adoptive transfer of TCR Tg T cells into κTg recipients resulted in T and B cell activation, lymphadenopathy, splenomegaly, and the production of IgG antichromatin antibodies by day 14. In most recipients, autoantibody levels increased with time, Tg T cells persisted for months, and a state of lupus nephritis developed. Despite this, Tg T cells appeared to be tolerant as assessed by severely diminished proliferative responses to the Vκ peptide. These results reveal the importance of attaining central and peripheral T cell tolerance to BCR V regions. They suggest that nondeletional forms of T tolerance in BCR-reactive T cells may be insufficient to preclude helper activity for chromatin-reactive B cells.


1977 ◽  
Vol 146 (1) ◽  
pp. 1-10 ◽  
Author(s):  
GK Lewis ◽  
JW Goodman

The capacity of the trinitrophenyl (TNP) haptenic group, coupled to a series of chemically dissimilar carriers, to cross-stimulate putative T- dependent and T-independent murine B-cell subpepulations was determined by using an in vitro limiting dilution technique to generate primary IgM responses. It was found that TNP-Ficoll and TNP-dextran, two T- independent antigens with little or no polyclonal mitogenicity, stimulate the same population of anti-TNP precursors, which is distinct from the precursor population activated by TNP-bacterial lipopolysaccharide (LPS), a T-independent polyclonal mitogen, or TNP-horse erythrocytes (HRBC), a T-dependent antigen. On the other hand, TNP-LPS and TNP-HRBC activate the same precursor population, indicating that LPS can substitute for the T- cell signal in T-dependent B-cell responses, whereas nonmitogenic T- independent antigens cannot. However, the cumulative evidence from this and other laboratories strongly indicates that LPS and T-dependent antigens activate B cells by different mechanisms. Of particular interest, LPS is incapable of activating B cells responsive to weakly- or nonmitogenic T-independent antigens. Based on clonal burst size, T-dependent antigens are capable of inducing greater antigen-specific B-cell proliferation than T-independent antigens. However, TNP conjugates of Ficoll and dextran, which are relatively poor inducers of polyclonal B-cell activation, induced larger anti-TNP clones than did TNP-LPS, a strong polyclonal mitogen. The findings reinforce the evidence favoring existence of multiple B- cell subpopulations with distinctive activation pathways. They also strengthen the proposition that a given B-cell subset can be activated by more than one mechanism.


2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 228.2-229
Author(s):  
N. Frede ◽  
J. Hueppe ◽  
R. Lorenzetti ◽  
A. Troilo ◽  
M. T. Schleyer ◽  
...  

Background:JAK inhibitors have been successfully introduced in the treatment of rheumatoid arthritis (RA) and psoriatic arthritis and are in clinical trials for numerous other autoimmune diseases. JAK inhibition effectively reduces cytokine-mediated activation and survival of pathology-driving immune cells by targeting signaling downstream of cytokine receptors. The outcome of such immunomodulation hence will largely depend on the intrinsic expression of the four different JAKs, the cytokine environment and the targeted cell type. Comparative studies investigating the effect on B cells are lacking. In light of the use of JAK inhibitor treatment in autoantibody mediated diseases, the study of the B cell compartment represents a milestone to assess their potential.Objectives:We thus aimed to study the B cell compartment as well as B cell function under JAK inhibition in RA patients and to compare the specific effect the JAK inhibitors tofacitinib (pan-JAK), baricitinib (JAK1/2), ruxolitinib (JAK1/2), upadacitinib and filgotinib (selective JAK1) on in vitro B cell activation, differentiation, proliferation, and class switch.Methods:B cell subpopulations in RA patients treated with baricitinib or tofacitinib was assessed by flow cytometric analysis of peripheral blood mononuclear cells. For in vitro studies, magnetically isolated total B cells from healthy donors were stimulated T-cell -independently with CpG and treated with scalar doses of the JAK inhibitors tofacitinib, baricitinib, ruxolitinib, upadacitinib and filgotinib. Flow cytometric analysis was performed on days 0, 3 and 6. Cytokine secretion was measured by Cytokine Multiplex Assay.Results:B cell phenotyping of RA patients treated with JAK inhibitors baricitinib or tofacitinib showed an increase in marginal zone (MZ) B cells. To investigate this further, we turned to an in vitro model of T-cell-independent B cell activation with CpG via TLR9, known to support MZ B cell expansion. Here, JAK1/2 and selective JAK1 inhibitor treatment led to a dose-dependent decrease of total B cell numbers. When assessing B cell-subpopulations, we observed an altered B cell differentiation with a significant increase in MZ-like B cells under JAK inhibition, which led to a subsequent increase in plasmablast differentiation in the first days. This effect was more pronounced upon pan-JAK inhibitor treatment than JAK1 or JAK1/2 inhibition, indicating that broader JAK inhibition is associated with a stronger effect (tofa > ruxo > bari > upa > filgo).Notably, we further detected a significant dose-dependent reduction of switched memory formation, strongest with JAK1/2 inhibition (upa > ruxo > bari > tofa > filgo). Consistent with this finding, we observed decreased AID expression under JAK inhibition. Concomitantly, induction of STAT3 expression and STAT3 phosphorylation were reduced under JAK inhibition, suggesting that downstream signalling was abrogated.To assess the role of autocrine signaling in this system, we measured cytokine secretion upon JAK inhibition and found that JAK2 inhibition led to reduced IL10 secretion. This in turn resulted in an increase of inflammatory cytokines such as IL6, TNF, highlighting the importance of B cell as cytokine-secreting cell type.Conclusion:In a T-independent in vitro B cell model JAK inhibition led to a reduced total B cell number as well as reduced switched memory development, whereas MZ-like B cells were increased. Especially JAK2 inhibition strongly impaired switched memory formation. JAK inhibition does not only impact cytokine signalling but also leads to changes in cytokine secretion dynamics and amounts, potentially impacting other cell types.In conclusion, JAK inhibition has a major effect on B cell activation and maturation, with differential outcomes between JAK inhibitors hinting towards distinct and unique effects on B cell homeostasis.Disclosure of Interests:None declared


1975 ◽  
Vol 142 (4) ◽  
pp. 928-935 ◽  
Author(s):  
E Heber-Katz ◽  
D B Wilson

This study provides a direct quantitative comparison of the helper effects of allogeneic and syngeneic rat T cells in the production of direct SRBC plaque-forming cell (PFC) responses by B cells in culture. In syngeneic T-B combinations, log-log plots of the number of PFC generated after 5.5 days in culture vs. the number of T cells employed as helpers showed a linear response between 10(4) and 2.5 times 10(5) T cells added. Allogeneic T-B combinations, in which the T cells possess the capacity for reactivity to major alloantigens of the B-cell donor, showed a different dose/response relationship in which PFC responses were decreased at high T/B ratios and augmented at low T/B rations. In this system responses were detected with as few as 10(3) allogeneic T cells. Use of negatively selected allogeneic T populations, specifically depleted of mixed lymphocyte interaction (MLI) and graft-vs-host reactivity for B-cell alloantigens, as helpers gave dose/response curves quantitatively identical to responses with syngeneic T-B combinations and also with F1 T-cell parental B-cell combinations. These data indicate that rat T and B cells need not share a major histocompatibility complex haplotype in order to collaborate effectively in a primary direct PFC response to SRBC in culture. In addition, the PFC response required the combinaed presence of T and B cells as well as antigen in the cultures, a finding consistent with the two signal model of B-cell activation. Finally, the dose/response data obtained suggest the possibility that although SRBC antigen is required in the cultures helper activity with low numbers of normal allogeneic T cells may not depend on T cells having specificity for this antigen.


2021 ◽  
Author(s):  
Darryl Hayward ◽  
Lesley Vanes ◽  
Stefanie Wissmann ◽  
Sujana Sivapatham ◽  
Harald Hartweger ◽  
...  

AbstractMigration and adhesion play critical roles in B cells, regulating recirculation between lymphoid organs, migration within lymphoid tissue and interaction with CD4+ T cells. However, there is limited knowledge of how B cells integrate chemokine receptor and integrin signaling with B cell activation to generate efficient humoral responses. Here we show that the WNK1 kinase, a regulator of migration and adhesion, is essential in B cells for T-dependent antibody responses. We demonstrate that WNK1 transduces signals from the BCR, CXCR5 and CD40, and using intravital imaging we show that WNK1 regulates migration of naive and activated B cells, and their interactions with T cells. Unexpectedly, we show that WNK1 is required for BCR- and CD40-induced proliferation, acting through the OXSR1 and STK39 kinases, and for efficient B cell-T cell collaboration in vivo. Thus, WNK1 is critical for humoral immune responses, by regulating B cell migration, adhesion and T cell-dependent activation.SummaryThe WNK1 kinase is essential in B cells for T-dependent antibody responses because it is activated by signaling from BCR, CXCR5 and CD40 and regulates B cell migration, adhesion, T-dependent activation, and differentiation into germinal center B cells and plasma cells.


1983 ◽  
Vol 157 (6) ◽  
pp. 1815-1827 ◽  
Author(s):  
G J Prud'homme ◽  
R S Balderas ◽  
F J Dixon ◽  
A N Theofilopoulos

B cell hyperactivity, a feature common to all lupus-prone murine strains, may be caused by hyperresponsiveness to, overproduction of, or bypassing of certain signals required for B cell activation, proliferation, and differentiation. In this study, we have compared the responses of B cells from three lupus-prone strains of mice (BXSB males, MRL and NZB/W females) and normal strains in a number of assays for which two or more signals are required to obtain a response. In medium to low density cultures of B cells from BXSB and NZB/W but not MRL/l lupus mice, the cells' proliferation induced by bacterial lipopolysaccharide (LPS) or anti-mu antibody was much higher than that of B cells from normal controls. At low B cell density, polyclonal activation by these substances and subsequent Ig secretion were dependent on accessory signals present in supernatants of concanavalin A-treated normal lymphocytes (CAS) or on the MRL/l proliferating T cell-derived B cell differentiation factor (L-BCDF) in both lupus-prone and immunologically normal mice. However, the responses of B cells from BXSB and NZB/W, but not MRL/l, mice to these accessory signals were higher than those of normal mice. Ig synthesis by fresh B cells of BXSB and NZB/W mice cultured in the absence of mitogens but in the presence of CAS or L-BCDF was higher than by similar cells from other strains, suggesting an increased frequency of B cells activated in vivo in these two autoimmune strains of mice. The patterns of IgG subclass secretion in response to LPS (without added CAS or L-BCDF) were abnormal in all lupus strains, with a predominance of IgG2b and/or IgG2a and low levels of IgG3, contrary to normal B cells for which IgG3 synthesis predominated. However, IgG1 synthesis in vitro by autoimmune and normal B cells alike was highly dependent on T cell-derived soluble mediators. Antigen-specific responses to SRBC in vitro of B cells from all lupus strains, like those of B cells from normal strains, required a minimum of three signals (antigen, LPS, T cell-derived antigen nonspecific helper factors). Yet, once triggered, B cells of BXSB and NZB/W mice gave higher responses than those of the other strains. We conclude that B cells of lupus mice have signal requirements similar to those of normal mice. Nevertheless, B cells of BXSB and NZB/W, but not MRL/l, lupus mice hyperrespond or process some accessory signals abnormally.


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