scholarly journals COMPLEMENT-DEPENDENT B-CELL ACTIVATION BY COBRA VENOM FACTOR AND OTHER MITOGENS?

1974 ◽  
Vol 139 (2) ◽  
pp. 337-354 ◽  
Author(s):  
Peter Dukor ◽  
Gebhard Schumann ◽  
Roland H. Gisler ◽  
Manfred Dierich ◽  
Wolfgang König ◽  
...  
Keyword(s):  
T Cells ◽  
Lymph Node ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
B Lymphocytes ◽  
Cell Cultures ◽  
Antibody Formation ◽  
Cell Activation ◽  
B Cell Activation

It has been proposed that two distinct signals are required for the triggering of the precursors of antibody-forming bone marrow-derived cells (B cells): (a) the binding of antigen or of a mitogen to the corresponding receptor sites on B-cell membranes and (b) the interaction of activated C3 with the C3 receptor of B lymphocytes. There is growing evidence that B-cell mitogens and T (thymus-derived cell)-independent antigens are capable of activating the alternate pathway of the complement system (bypass). Therefore, the effect of another potent bypass inducer was investigated with regard to B-cell activation and the role of C3. Purified, pyrogen-free cobra venom factor was mitogenic for both T and B lymphocytes (cortisone-resistant mouse thymus cells and lymph node lymphocytes from congenitally athymic mice). Venom factor could substitute for T cells by restoring the potential of antibody formation to sheep red blood cells in mouse B-cell cultures supplemented with macrophages or 2-mercaptoethanol. Venom factor may be capable of conferring activated C3 to the C3 receptor of B lymphocytes: preincubation of lymphoid cells with homologous serum or plasma, 10 mM EDTA, and sepharose-coupled venom factor converted with serum to an enzyme active against C3, inhibited their capacity to subsequently form rosettes with sheep erythrocytes sensitized with amboceptor and C5-deficient mouse complement. In the absence of EDTA, preincubation of freshly prepared B-cell suspensions with C3-sufficient homologous serum also blocked their subsequent interaction with complement-sensitized erythrocytes and at the same time rendered them reactive to an otherwise T-cell-specific mitogen. Moreover, mitogen induced B-cell proliferation in lymph node (but not in spleen) cell cultures, appeared to depend on the availability of exogenous C3: zymosan-absorbed fetal bovine serum (only 8.3% site-forming units remaining) supported T-cell activation by phytohemagglutinin, concanavalin A, and venom factor, but failed to sustain B-cell stimulation by pokeweed mitogen, lipopolysaccharide, and venom factor. T-cell-dependent antibody formation in composite cultures containing T cells or T-cell-substituting B-cell mitogens, B cells, and macrophages, always required the presence of C3-sufficient serum.

scholarly journals T Cell Accumulation in B Cell Follicles Is Regulated by Dendritic Cells and Is Independent of B Cell Activation

2003 ◽  
Vol 197 (2) ◽  
pp. 195-206 ◽  
Author(s):  
Simon Fillatreau ◽  
David Gray
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Cell Activation ◽  
B Cell Activation ◽  
Cell Accumulation ◽  
Antigen Presenting ◽  
Deficient Mice

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.

scholarly journals Antigen presentation by resting B cells. Radiosensitivity of the antigen-presentation function and two distinct pathways of T cell activation.

1984 ◽  
Vol 159 (3) ◽  
pp. 881-905 ◽  
Author(s):  
J D Ashwell ◽  
A L DeFranco ◽  
W E Paul ◽  
R H Schwartz
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Antigen Presentation ◽  
Cell Activation ◽  
T Cell Proliferation ◽  
B Cell Activation ◽  
Antigen Presenting

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).

scholarly journals Effects of Friend Virus Infection and Regulatory T Cells on the Antigen Presentation Function of B Cells

mBio ◽  
2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Tyler C. Moore ◽  
Ronald J. Messer ◽  
Lorena M. Gonzaga ◽  
Jennifer M. Mather ◽  
Aaron B. Carmody ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
Regulatory T Cells ◽  
B Cell ◽  
Cell Activation ◽  
T Cell Responses ◽  
B Cell Activation ◽  
Friend Virus ◽  
Cell Responses

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.

Leukotriene B4 activates T cells that inhibit B-cell proliferation in EBV-infected cord blood–derived mononuclear cell cultures

Blood ◽  
2008 ◽  
Vol 111 (5) ◽  
pp. 2693-2703 ◽  
Author(s):  
Anquan Liu ◽  
Hans-Erik Claesson ◽  
Yilmaz Mahshid ◽  
George Klein ◽  
Eva Klein
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Cord Blood ◽  
B Cell ◽  
B Lymphocytes ◽  
Cell Cultures ◽  
T Cell Activation ◽  
Cell Activation ◽  
Leukotriene B4

Epstein-Barr virus (EBV)–specific cellular memory is not transferred from mother to child. Therefore, EBV-induced B-cell proliferation in in vitro–infected cord blood mononuclear cell cultures is not inhibited. However, by addition of immunomodulators, polysaccharide K (PSK) or truncated thioredoxin (Trx80) that activate monocytes, EBV-specific T-cell response could be generated in such cultures. Presently, we demonstrate that leukotriene B4 (LTB4) is involved in the effect of the immunomodulators. LTB4 was detected in the medium, and T-cell activation was compromised by addition of leukotriene biosynthesis inhibitors. Moreover, we found that LTB4 added to infected cultures, which did not receive the immunomodulators, induced functional activation of the T cells. LTB4 activated the monocytes and acted directly on the T cells. In consequence, addition of LTB4 inhibited the EBV-induced proliferation of B lymphocytes. Specific cytotoxicity could be generated by restimulation of the T cells. The experiments showed successive stages of T-cell activation in acquisition of their immunologic effector function. This is orchestrated by complex cellular interactions, and autocrine loops mediated by soluble factors—here interferon (IFN)-γ, interleukin (IL)-15, IL-12, and LTB4. Importantly, the results indicate that endogenous LTB4 can induce T-cell activation that inhibits the EBV-induced proliferation of B lymphocytes.

scholarly journals Activation and Tolerance in CD4+ T Cells Reactive to an Immunoglobulin Variable Region

2004 ◽  
Vol 200 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Christopher M. Snyder ◽  
Katja Aviszus ◽  
Ryan A. Heiser ◽  
Daniel R. Tonkin ◽  
Amanda M. Guth ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Cell Activation ◽  
Variable Region ◽  
Cell Receptor ◽  
B Cell Activation ◽  
Antibody Diversity ◽  
Helper Activity

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.

scholarly journals B cell-intrinsic requirement for WNK1 kinase in T cell-dependent antibody responses

2021 ◽  
Author(s):  
Darryl Hayward ◽  
Lesley Vanes ◽  
Stefanie Wissmann ◽  
Sujana Sivapatham ◽  
Harald Hartweger ◽  
...  
Keyword(s):  
T Cells ◽  
Cell Migration ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Cell Activation ◽  
Plasma Cells ◽  
Antibody Responses ◽  
B Cell Activation

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.

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
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Cell Activation ◽  
Free Carrier ◽  
B Cell Activation ◽  
High Concentrations ◽  
Cell Subpopulations

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.

scholarly journals Activation of B lymphocytes by monovalent anti-Lyb-2 antibodies.

1984 ◽  
Vol 159 (6) ◽  
pp. 1796-1801 ◽  
Author(s):  
B Subbarao ◽  
D E Mosier
Keyword(s):  
T Cells ◽  
B Cells ◽  
B Cell ◽  
B Lymphocytes ◽  
Cell Activation ◽  
Cell Transformation ◽  
Receptor Occupancy ◽  
Cross Linking ◽  
B Cell Activation ◽  
Fab Fragments

Although activation of B lymphocytes by antigen or anti-Ig antibody has been shown to require cross-linking of surface Ig molecules, cross-linking is not necessary for B cell activation by anti-Lyb-2 monoclonal antibody (MAb). Monovalent Fab' fragments of anti-Lyb-2 MAb are as effective as the intact antibody in inducing blast cell transformation of small B cells and B cell proliferation in the apparent absence of T cells and adherent cells. In the presence of factors from T cells, B cells activated by Fab' fragments of anti-Lyb-2 MAb were induced to mature into Ig-secreting cells. Since monovalent Fab' fragments probably cannot induce receptor aggregation, it appears that receptor occupancy is sufficient to induce B cell activation with anti-Lyb-2 MAb.

scholarly journals Role of B lymphocytes in cell-mediated immunity. I. Requirement for T cells or T-cell products for antigen-induced B-cell activation.

1976 ◽  
Vol 144 (5) ◽  
pp. 1175-1187 ◽  
Author(s):  
S M Wahl ◽  
D L Rosenstreich
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cell ◽  
B Lymphocytes ◽  
Cell Activation ◽  
Chemotactic Factor ◽  
Cell Mediated Immunity ◽  
B Cell Activation ◽  
T Cell Factor ◽  
T Cell Help

Although B lymphocytes can be triggered by B-cell mitogens and by certain other molecules to produce lymphokines, they do not produce lymphokines when stimulated with specific soluble protein antigens. We have investigated whether T-cell help would enable B cells to produce lymphokines when activated by antigens. Addition of small numbers of T cells to B-cell cultures resulted in significant production of a monocyte chemotactic factor. T cells could be replaced by supernates of antigen-stimulated T cells, demonstrating both that the chemotactic factor was B-cell-dervied and that T-cell help was mediated by a soluble factor. Although the T-cell factor was nonantigen specific, B-cell activation required the presence of both antigen and T-cell factor. Thus, it appears that although dependent upon T cells, B lymphocytes may play an important role in amplification of cell-mediated immune responses.

scholarly journals N-WASP is required for B-cell–mediated autoimmunity in Wiskott-Aldrich syndrome

Blood ◽  
2016 ◽  
Vol 127 (2) ◽  
pp. 216-220 ◽  
Author(s):  
Stefano Volpi ◽  
Elettra Santori ◽  
Katrina Abernethy ◽  
Masayuki Mizui ◽  
Carin I. M. Dahlberg ◽  
...  
Keyword(s):  
T Cell ◽  
B Cells ◽  
B Cell ◽  
B Lymphocytes ◽  
Cell Activation ◽  
B Cell Activation ◽  
Wiskott Aldrich Syndrome ◽  
Key Points ◽  
Deficient Mice

Key Points Mice lacking both WASP and N-WASP in B lymphocytes have impaired response to T-cell-dependent antigens and defective B-cell activation. Deletion of N-WASP in B cells attenuates autoimmunity in WASP-deficient mice.

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