scholarly journals Inhibition of normal B-cell function by human immunodeficiency virus envelope glycoprotein, gp120

Blood ◽  
1992 ◽  
Vol 79 (5) ◽  
pp. 1245-1254 ◽  
Author(s):  
N Chirmule ◽  
N Oyaizu ◽  
VS Kalyanaraman ◽  
S Pahwa
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Cell Function ◽  
Cell Contact ◽  
Cell Proliferation And Differentiation ◽  
Cell Clones ◽  
Glycoprotein Gp120

Abstract Despite the occurrence of hypergammaglobulinemia in human immunodeficiency virus (HIV) infection, specific antibody production and in vitro B-cell differentiation responses are frequently impaired. In this study, we have examined the effects of HIV envelope glycoprotein gp120 on T-helper cell function for B cells. In the culture system used, B-cell functional responses were dependent on T-B- cell contact, since separation of T and B cells in double chambers by Transwell membranes rendered the B cells unresponsive in assays of antigen-induced B-cell proliferation and differentiation. Cytokines secreted by T cells were also essential, since anti-CD3 monoclonal antibody (mAb)-activated, paraformaldehyde-fixed T-cell clones failed to induce B-cell proliferation and differentiation. Pretreatment of the CD4+ antigen-specific T cells with gp120 was found to impair their ability to help autologous B cells, as determined by B-cell proliferation, polyclonal IgG secretion, and antigen-specific IgG secretion. The gp120-induced inhibition was specific in that it was blocked by soluble CD4. Furthermore, only fractionated small B cells (which are T-cell-dependent in their function) manifested impaired responses when cultured with gp120-treated T cells. Antigen-induced interleukin (IL)-2 and IL-4, but not IL-6, secretion were markedly reduced in gp120-treated T-cell clones. Addition of exogenous cytokines failed to compensate for defective helper function of gp120-treated T cells. The findings in this study indicate that gp120 impairs helper functions of CD4+ T cells by interfering with T-B-cell contact- dependent interaction; the inhibitory effects of soluble envelope proteins of HIV may contribute to the immunopathogenesis of the HIV- associated disease manifestations.

scholarly journals Inhibition of normal B-cell function by human immunodeficiency virus envelope glycoprotein, gp120

Blood ◽  
1992 ◽  
Vol 79 (5) ◽  
pp. 1245-1254
Author(s):  
N Chirmule ◽  
N Oyaizu ◽  
VS Kalyanaraman ◽  
S Pahwa
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Cell Function ◽  
Cell Contact ◽  
Cell Proliferation And Differentiation ◽  
Cell Clones ◽  
Glycoprotein Gp120

Despite the occurrence of hypergammaglobulinemia in human immunodeficiency virus (HIV) infection, specific antibody production and in vitro B-cell differentiation responses are frequently impaired. In this study, we have examined the effects of HIV envelope glycoprotein gp120 on T-helper cell function for B cells. In the culture system used, B-cell functional responses were dependent on T-B- cell contact, since separation of T and B cells in double chambers by Transwell membranes rendered the B cells unresponsive in assays of antigen-induced B-cell proliferation and differentiation. Cytokines secreted by T cells were also essential, since anti-CD3 monoclonal antibody (mAb)-activated, paraformaldehyde-fixed T-cell clones failed to induce B-cell proliferation and differentiation. Pretreatment of the CD4+ antigen-specific T cells with gp120 was found to impair their ability to help autologous B cells, as determined by B-cell proliferation, polyclonal IgG secretion, and antigen-specific IgG secretion. The gp120-induced inhibition was specific in that it was blocked by soluble CD4. Furthermore, only fractionated small B cells (which are T-cell-dependent in their function) manifested impaired responses when cultured with gp120-treated T cells. Antigen-induced interleukin (IL)-2 and IL-4, but not IL-6, secretion were markedly reduced in gp120-treated T-cell clones. Addition of exogenous cytokines failed to compensate for defective helper function of gp120-treated T cells. The findings in this study indicate that gp120 impairs helper functions of CD4+ T cells by interfering with T-B-cell contact- dependent interaction; the inhibitory effects of soluble envelope proteins of HIV may contribute to the immunopathogenesis of the HIV- associated disease manifestations.

scholarly journals Activated CD4+CD25+ T cells selectively kill B lymphocytes

Blood ◽  
2006 ◽  
Vol 107 (10) ◽  
pp. 3925-3932 ◽  
Author(s):  
Dong-Mei Zhao ◽  
Angela M. Thornton ◽  
Richard J. DiPaolo ◽  
Ethan M. Shevach
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
Cell Death ◽  
B Cells ◽  
B Cell ◽  
T Cell Activation ◽  
Fas Ligand ◽  
Cell Function ◽  
Cell Contact ◽  
Dependent Manner

The suppressive capacity of naturally occurring mouse CD4+CD25+ T cells on T-cell activation has been well documented. The present study is focused on the interaction of CD4+CD25+ T cells and B cells. By coculturing preactivated CD4+CD25+ T cells with B cells in the presence of polyclonal B-cell activators, we found that B-cell proliferation was significantly suppressed. The suppression of B-cell proliferation was due to increased cell death caused by the CD4+CD25+ T cells in a cell-contact–dependent manner. The induction of B-cell death is not mediated by Fas–Fas ligand pathway, but surprisingly, depends on the up-regulation of perforin and granzymes in the CD4+CD25+ T cells. Furthermore, activated CD4+CD25+ T cells preferentially killed antigen-presenting but not bystander B cells. Our results demonstrate that CD4+CD25+ T cells can act directly on B cells and suggest that the prevention of autoimmunity by CD4+CD25+ T cells can be explained, at least in part, by the direct regulation of B-cell function.

Chronic Lymphocytic Leukemia Cells Acquire a Regulatory B-Cell Phenotype Modified By PD1 Signaling

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 3319-3319 ◽  
Author(s):  
Shimrit Ringelstein-Harlev ◽  
Irit Avivi ◽  
Shoham Shivtiel-Arad ◽  
Tami Katz
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
B Cells ◽  
Immune Responses ◽  
B Cell ◽  
Immune Modulation ◽  
Lymphocytic Leukemia ◽  
T Cell Proliferation ◽  
Cell Contact

Abstract Introduction: Chronic lymphocytic leukemia (CLL) cells utilize several mechanisms of survival, some propagating proliferation and preventing apoptosis through intrinsic cell cycle signals, and others suppressing anti-tumor immune responses. Patients often present with a predominant population of regulatory T-cells (Tregs), and general features of T-cell exhaustion. Given the unique phenotype of CLL cells and the observed T-cell abnormalities we hypothesized that these cells function as regulatory B-cells (Bregs). Bregs, mostly explored in the autoimmune disease setting, produce interleukin-10 (IL10), which mediates attenuation of effector T-cell responses and enhances regulatory activity. These features have also been suggested to be responsible for weakening of anti-tumor immune responses. Breg activation requires stimulation of various combinations of Toll-like receptors (TLRs), the B-cell receptor (BCR) and CD40. Our previous studies have demonstrated that TLR9-stimulated CLL cells "acquire" Breg markers as well as PD1 and PDL1, which, while not being classic Breg discriminators, are established players in immune modulation. Moreover, such stimulation resulted in inhibition of proliferation of autologous T-cells. The current study aimed to further explore the regulatory characteristics of CLL cells focusing on additional suppressive mechanisms that may have a role in CLL immune evasion, particularly, the PD1/PDL1 axis. Methods: B-cells were isolated from peripheral blood mononuclear cells (PBMCs) of untreated CLL patients (Rai stages 0-IV). These B-CLL cells were stimulated with TLR-9 agonist (ODN) or CD40 ligand (CD40L) followed by their co-culture with isolated autologous CD4+ T cells. The regulatory features of B-CLL cells were studied by testing their effect on T cells. Their proliferation was evaluated using the CFSE method following stimulation with anti-CD3/CD28 antibodies and IL2; induction of Tregs (CD4+CD25highFoxp3+ population) was assessed by FACS analysis. The involvement of the PD1/PDL1 axis was examined by incubating B-cells with antiPD1 neutralizing antibodies prior to co-culture. Cell contact dependence was evaluated by plating B-cells in hanging cell culture inserts denying B and T cell contact while allowing flow of small soluble molecules. Results: CLL cells stimulated with ODN or CD40L, induced a significant increase in Tregs: 1.35±0.1-fold (p=0.03, N=12) for ODN and 1.7±0.2-fold (p=0.008, N=14) for CD40L, occurring in 68% and 80% of patients, respectively, while co-culture with unstimulated B-CLL cells did not result in the expansion of the Treg population. Treg induction was observed only under contact conditions (N=5), suggesting that this regulatory function requires cell-to-cell contact and cannot be carried out solely by secreted factors like IL10. Neutralization of PD1 on CLL B-cells affects both Treg induction and T-cell proliferation. Following CD40L stimulation, a 1.3-fold reduction in Treg percentage was observed when PD1 signaling was blunted (N=10). In contrast, PD1 blockage of ODN-stimulated CLL cells did not reduce Treg induction; however, it did adversely affect inhibition of T-cell proliferation (10%-decrease in inhibited T-cells; N=6). Conclusions: CLL cells "acquire" a Breg phenotype and function, inhibiting T-cell proliferation and inducing Tregs. These properties, while working together to promote immune regulation and cancer evasion, are elicited by different ligands in the cell environment and are likely to be mediated via separate pathways. The involvement of B-cell-associated PD1 in the induction of Tregs and inhibition of T-cell proliferation suggests a biologic role of PD1 signaling in CLL cells, strengthening the Breg phenotype. The current study has shown that CLL cells recruit several mechanisms operating cooperatively to support immune modulation and promote their survival. Disclosures No relevant conflicts of interest to declare.

Chronic Lymphocytic Leukemia Cells Exhibit Inhibitory Properties of Regulatory B Cells

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 3874-3874
Author(s):  
Shimrit Ringelstein-Harlev ◽  
Irit Avivi ◽  
Lina Bisharat ◽  
Tamar Katz
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Fold Increase ◽  
Lymphocytic Leukemia ◽  
T Cell Proliferation ◽  
Cell Contact ◽  
Stimulation Of

Abstract Abstract 3874 Background: Chronic lymphocytic leukemia (CLL) is a mature B-cell malignancy, characterized by distinct immune suppression rendering both tumor cells and invading pathogens invisible to the immune system. However, CLL cells also display profound immune sensitivity as proven by long-term remissions achieved with allogeneic bone marrow transplantation. Many phenotypic properties of B-CLL cells resemble a subset of B-cells, studied mostly in autoimmunity and termed regulatory B cells (Bregs). Bregs are thought to suppress CD4+ T-cell mediated immune responses, directly through cell contact and indirectly through inhibitory cytokines. This study aims to define whether malignant B-CLL cells exhibit Breg suppressive properties, contributing to immune dysfunction in this disease. Methods: B-cells were isolated from peripheral blood mononuclear cells (PBMCs) of untreated CLL patients (Rai stages 0-IV) using immunomagnetic separation (STEMCELL technologies). Naïve cells and those stimulated with B-cell activators TLR-9 agonist or CD40Ligand (CD40L) were analyzed by FACS for Breg phenotypic markers and intracellular IL-10. Additionally, B-CLL cell effects on autologous CD4+ T cells (isolated by immunomagnetic beads; Miltenyi Biotec) were studied. T-cells were stimulated with anti-CD3/CD28 antibodies and IL-2, and exposed to B-cells either directly or through hanging cell culture inserts (Millipore) preventing physical cell-cell contact. T-cell proliferation was assessed using the carboxyfluorescein diacetate succinimidyl ester (CFSE) method and phenotype was analyzed by FACS. Results: B-cell phenotype was studied in 11 patients. Breg markers (CD5, CD38, CD25 and intracellular IL-10) as well as inhibitory molecules PD-1 and PDL-1 were expressed at high levels on B-CLL cells (62%, 37%, 50%, 52%, 29%, 61%, respectively), although not every patient expressed all markers. These expression levels were higher than those reported for normal peripheral blood B-cells. TLR-9 stimulation of B-CLL cells resulted in a 5.7-fold increase in expression of CD25 in 77% of patients. Increments were also observed in IL-10 (1.9-fold; 62% of patients), PDL-1 (1.96-fold; 83% of patients) and PD-1 (2.19-fold; 57% of patients). Of 13 patients whose T-cell proliferation potential was evaluated after exposure to B-CLL cells, proliferation was induced in only 69%; in the other 31% (4 patients) no proliferation was observed; moreover, inhibition was demonstrated in one of them. Among the former group only 33% of patients expressed CD25 on their B-cells, whereas within the latter group, 75% of patients' B-cells were CD25-positive. Stimulation of B-CLL cells with TLR-9 markedly increased their inhibitory capacity (72% of 11 patients tested), while CD40L stimulation caused a weaker effect (50% of 6 patients tested). T-cell proliferation remained unchanged when evaluated using a Transwell system versus a contact system, as demonstrated in 3 of 4 experiments. T-cells exposed to B-CLL cells altered the ratio of CD25high vs. CD25low T-cells in favor of CD25 high cells (2.44-fold increase for stimulation with naïve B-CLL cells, 4.94-fold increase with TLR-9 stimulated cells; in all the 5 tested patients). Conclusions: Previously identified Breg markers as well as PD-1 and PDL-1 were highly expressed in B-CLL cells, supporting the role of these cells in shaping an immune tolerant environment, enabling tumor growth. Stimulation of B-CLL cells with TLR-9 agonist enhanced this phenotype and resulted in consistent inhibition of T-cell proliferation, likely to be independent of cell-to-cell contact. These findings demonstrate the presence of Breg features within the CLL clone. The observed alterations in CD4+CD25+ T-cell populations after exposure to B-CLL cells suggest induction of T-regulatory cells, another mechanism supposedly used by Bregs for immune suppression. The enhancement of Breg properties in B-CLL cells following B-cell activation can serve as a platform for further studies of the innate regulatory mechanisms utilized by tumor cells. Disclosures: No relevant conflicts of interest to declare.

scholarly journals The role of H-2-linked genes in helper T cell function. VII. Expression of I region and immune response genes by B cells in bystander help assays.

1980 ◽  
Vol 152 (5) ◽  
pp. 1274-1288 ◽  
Author(s):  
P Marrack ◽  
J W Kappler
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Cell Function ◽  
High Responder ◽  
Helper T Cells ◽  
Spleen Cells ◽  
Region Gene ◽  
Immunoglobulin Receptor

The mode of action by bystander helper T cells was investigated by priming (responder X nonresponder) (B6A)F1 T cells with poly-L-(Tyr, Glu)-poly-D,L-Ala--poly-L-Lys [(TG)-A--L] and titrating the ability of these cells to stimulate an anti-sheep red blood cell (SRBC) response of parental B cells and macrophages in the presence of (TG)-A--L. Under limiting T cell conditions, and in the presence of (TG)-A--L, (TG)-A--L-responsive T cells were able to drive anti-SRBC responses of high-responder C57BL/10.SgSn (B10) B cells and macrophages (M0), but not of low-responder (B10.A) B cells and M0. Surprisingly, the (TG)-A--L-driven anti-SRBC response of B10.A B cells was not restored by addition of high-responder acessory cells, in the form of (B6A)F1 peritoneal or irradiated T cell-depleted spleen cells, or in the form of B10 nonirradiated T cell-depleted spleen cells. These results suggested that (TG)-A--L-specific Ir genes expressed by B cells controlled the ability of these cells to be induced to respond to SRBC by (TG)-A--L-responding T cells, implying that direct contact between the SRBC-binding B cell precursor and the (TG)-A--L-responsive helper T cells was required. Analogous results were obtained for keyhold limpet hemocyanin (KLH)-driven bystander help using KLH-primed F1 T cells restricted to interact with cells on only one of the parental haplotypes by maturing them in parental bone marrow chimeras. It was hypothesized that bystander help was mediated by nonspecific uptake of antigen [(TG)-A--L or KLH] by SRBC-specific b cells and subsequent display of the antigen on the B cell surface in association with Ir of I-region gene products, in a fashion similar to the M0, where it was then recognized by helper T cells. Such an explanation was supported by the observation that high concentrations of antigen were required to elicit bystander help. This hypothesis raises the possibility of B cell processing of antigen bound to its immunoglobulin receptor and subsequent presentation of antigen to helper T cells.

scholarly journals Induction of human IgE synthesis by CD4+ T cell clones. Requirement for interleukin 4 and low molecular weight B cell growth factor.

1989 ◽  
Vol 170 (5) ◽  
pp. 1477-1493 ◽  
Author(s):  
R H DeKruyff ◽  
T Turner ◽  
J S Abrams ◽  
M A Palladino ◽  
D T Umetsu
Keyword(s):  
Molecular Weight ◽  
T Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Cd4 T Cell ◽  
Low Molecular Weight ◽  
Cell Clones ◽  
B Cell Growth Factor ◽  
Ige Synthesis

We have analyzed in detail the precise requirements for the induction of human IgE synthesis using several experimental approaches with purified B cells and well-characterized alloantigen-specific CD4+ T cell clones expressing different profiles of lymphokine secretion. Using these clones under cognate conditions in which the B cells expressed alloantigens recognized by the cloned T cells, we have confirmed that IL-4 is required for the induction of IgE synthesis, but we have clearly demonstrated that IL-4 by itself is not sufficient. With several cloned CD4+ T cell lines, including an IL-4-producing clone that could not induce IgE synthesis, and cloned T cells pretreated with cyclosporin A to inhibit lymphokine synthesis, we showed that Th cell-B cell interactions are necessary for IgE synthesis, and that low molecular weight B cell growth factor (LMW-BCGF) and IL-4, in combination, are lymphokines of major importance in the induction of IgE synthesis. Together our results indicate that optimal induction of an IgE-specific response requires the exposure of B cells to a particular complex of signals that include (a) a signal(s) involving Th-B cell interaction that primes B cells to receive additional signals from soluble lymphokines, (b) a specific B cell proliferative signal provided by LMW-BCGF, and (c) a specific B cell differentiation signal provided by IL-4.

scholarly journals T cell regulation of IgG subclass antibody production in response to T-independent antigens.

1981 ◽  
Vol 153 (1) ◽  
pp. 1-12 ◽  
Author(s):  
P K Mongini ◽  
K E Stein ◽  
W E Paul
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Heavy Chain ◽  
Chain Gene ◽  
Cell Clones ◽  
T Cell Regulation ◽  
The Difference

The effect of T lymphocytes on the IgM, IgG3, IgG1, IgG2b, and IgG2a responses of B lymphocytes to the type-2 T-independent antigens, trinitrophenylated (TNP)-Ficoll, and TNP-Levan, was investigated. T cell-bearing nu/+ mice were found to produce substantially higher IgG2 serum anti-TNP antibody than their athymic counterparts, and nu/nu and nu/+ IgG2a titers exhibiting more disparity than nu/nu and nu/+ IgG2b titers. The Igm, IgG3, and IgG1 anti-TNP levels in nu/nu and nu/+ mice were indistinguishable. By cell transfer experiments, it was determined that this variance in nude and heterozygote IgG2 responses could not be explained by B cell differences between the two strains or by suppressive effects on IgG2 production within nu/nu mice. Rather, the difference was shown to be the result of the absence of T cells at the time B cells were responding to antigen. In the absence of T cells, the strength of the nu/nu anti-TNP antibody response was found to be in the following order: IgM > IgG3 > IgG1 > IgG2b > IgG2a, a heirarchy identical with the recently proposed heavy chain gene order. The possibilities that T cells influence IgG2 production via their specific recognition of IgG2-bearing B cells or via signals to increase heavy chain switching of responding B cell clones are discussed.

scholarly journals Heterogeneity of helper/inducer T lymphocytes. II. Effects of interleukin 4- and interleukin 2-producing T cell clones on resting B lymphocytes.

1988 ◽  
Vol 167 (4) ◽  
pp. 1350-1363 ◽  
Author(s):  
W H Boom ◽  
D Liano ◽  
A K Abbas
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
B Lymphocytes ◽  
Th1 Cells ◽  
Specific Class ◽  
Ifn Gamma ◽  
T Cell Clones ◽  
Cell Clones

To compare the helper function of murine T cell clones that secrete IL-2 and IFN-gamma (Th1 cells) or IL-4 and IL-5 (Th2), purified resting B cells were stimulated with F(ab')2 rabbit anti-mouse Ig (RAMG) and rabbit Ig-specific, class II MHC-restricted cloned T cells belonging to the two subsets. Both Th2 clones examined induced strong proliferative responses of B cells in the presence of RAMG, as well as the secretion of IgM and IgG1 antibodies. In contrast, the Th1 clones tested failed to stimulate B cell growth or antibody secretion. Th2-mediated B cell activation was dependent on IL-4 and IL-5, and was also inhibited by IFN-gamma or IFN-gamma produced by Th1 cells present in the same cultures. However, the failure of Th1 cells to help resting B cells could not be reversed with neutralizing anti-IFN-gamma antibody. In addition to this inhibitory effect, IFN-gamma was required for the secretion of IgG2a antibody, particularly when B cells were stimulated with polyclonal activators such as LPS. Finally, both sets of T cell clones secreted lymphokines when stimulated with purified B cells and RAMG. These experiments demonstrate that T cells that differ in lymphokine production also differ in their ability to help B cells as a result of cognate interactions at low concentrations of antigens. Moreover, IL-4, IL-5, and IFN-gamma serve different roles in the T cell-dependent proliferative and differentiative responses of resting B lymphocytes.

scholarly journals Human Germinal Center CD4+CD57+T Cells Act Differently On B Cells Than Do Classical T-Helper Cells

1995 ◽  
Vol 4 (3) ◽  
pp. 189-197 ◽  
Author(s):  
Farida Bouzahzah ◽  
Alain Bosseloir ◽  
Ernst Heinen ◽  
Léon J. Simar
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Germinal Center ◽  
Functional Study ◽  
Target Cells ◽  
Helper Cells ◽  
Ig Synthesis

We have isolated two subtypes of helper T cells from human tonsils: CD4+CD57+cells, mostly located in the germinal center (GC), and CD4+CD57-cells, distributed through the interfollicular areas but also present in the GC. In a functional study, we have compared the capacities of these T-cell subtypes to stimulate B cells in cocultures. In order to block T-cell proliferation while maintaining their activation level, we pretreated isolated T cells with mitomycin C prior to culture in the presence of B cells and added polyclonal activators such as PHA and Con A, combined or not with IL-2. Contrary to CD4+CD57-cells, CD4+CD57+cells did not markedly enhance B-cell proliferation. Even when sIgD-B cells typical of germinal center cells were tested, the CD4 CD57 cells had no significant effect. This is in accordance with the location of these cells: They mainly occupy the light zones of the GC where few B cells divide. Even when added to preactivated, actively proliferating cells, CD4+CD57+cells failed to modulate B-cell multiplication. On the supernatants of B-cell-T-cell cocultures, we examined by the ELISA technique the effect of T cells on Ig synthesis. Contrary to CD57-T cells, whose effect was strong, CD57+T cells weakly stimulated Ig synthesis. More IgM than IgG was generally found. Because CD57 antigen is a typical marker of natural killer cells, we tested the cytolytic activity of tonsillar CD4+CD57+cells on K562 target cells. Unlike NK cells, neither CD4+CD57+nor CD4+CD57-cells exhibit any cytotoxicity. Thus, germinal center CD4+CD57+cells are not cytolytic and do not strongly stimulate either B-cell proliferation or Ig secretion. CD4+CD57-cells, however, enhance B-cell proliferation and differentiation, thus acting like the classical helper cells of the T-dependent areas.

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).

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