RANTES is produced by CD8+ T cells during acute rejection of skin grafts.
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Acute Disease↗
Biomedical subjects
R L Fairchild
Publications and source records attributed to R L Fairchild.
T cell infiltration into class II MHC-disparate allografts and acute rejection is dependent on the IFN-gamma-induced chemokine Mig.
Direct evidence that cytokines with chemoattractant properties for leukocytes, chemokines, recruit alloantigen-primed T cells into transplanted allografts has been lacking. We present evidence that neutralization of a single chemokine inhibits T cell infiltration into class II MHC-disparate murine allografts and acute rejection. The chemokines IFN-gamma-inducible protein-10 and monokine induced by IFN-gamma (Mig) are expressed in allogeneic skin grafts during the late stages of acute rejection. Survival of class II MHC-disparate B6.H-2bm12 allografts is prolonged from day 14 to day 55 posttransplant when C57BL/6 recipients are given a short course treatment with an antiserum to Mig. This treatment also inhibits T cell and macrophage infiltration into the allografts. B6.H-2bm12 allografts are also not rejected by IFN-gamma-/- C57BL/6 recipients. Injection of Mig directly into B6.H-2bm12 grafts on IFN-gamma-deficient recipients restores T cell infiltration and rejection. Therefore, the inability of IFN-gamma-deficient recipients to reject the class II MHC-disparate allografts is due to the lack of intraallograft Mig production and alloantigen-primed T cell recruitment to the graft. These results indicate for the first time the potential utility of chemokine neutralization strategies in preventing T cell infiltration into allografts and abrogating acute rejection.
Acute Disease↗
CD8+ T cells produce RANTES during acute rejection of murine allogeneic skin grafts.
BACKGROUND: Based on their chemoattractant properties, it is likely that chemokines play a role in recruiting alloantigen-primed T cells to allografts and in amplifying inflammation within the graft. The graft-infiltrating leukocytes producing specific chemokines remain largely unknown. METHODS: We tested the intragraft RNA expression of the chemokine RANTES (regulated on activation normal T expressed and secreted) and granzyme B during rejection of full thickness, allogeneic skin grafts by C57BL/6 mice. Grafts with different immunogenetic disparities were chosen to test expression when rejection was mediated by CD4+, CD8+, or both CD4+ and CD8+ T cells. RNA expression was also tested in purified CD4+ and CD8+ T cell populations from skin graft recipients. Immunohistology was performed on graft sections to test colocalization of RANTES protein and graft-infiltrating CD4+ and CD8+ T cells. RESULTS: Intra-allograft RANTES RNA expression was not observed during CD4+ T cell-mediated rejection. Expression of RANTES and granzyme B RNA was observed at low levels in purified populations of CD8+, but not CD4+, T cells from the spleen and lymph nodes of graft recipients beginning at day 7 after transplantation and increased thereafter. Intra-allograft RANTES protein was associated with a small number of graft-infiltrating CD8+ T cells but was also associated with endothelial cells and with many graft-infiltrating CD4+ T cells. CONCLUSIONS: CD8+ T cells produce RANTES during allogeneic skin graft rejection. In the allograft, the chemokine also colocalizes with CD4+ T cells that do not produce RANTES.
Acute Disease↗
Groalpha-mediated recruitment of neutrophils is required for elicitation of contact hypersensitivity.
The factors mediating recruitment of immune T cells to challenge sites during contact hypersensitivity (CHS) responses remain unclear. To investigate the role of chemokines during elicitation of CHS, the temporal expression of chemokine genes in hapten-challenged ears was tested. KC (the murine homologoue of Groalpha) was expressed 30 min following hapten challenge in naive and hapten-sensitized mice. A rabbit KC-specific antiserum inhibited elicitation of CHS when administered to sensitized mice prior to hapten challenge. Injecting either neutrophils or immune CD8(+) T cells into the ear tissue of immune animals before hapten challenge circumvented the KC antiserum-mediated inhibition of CHS. Neutrophil depletion also inhibited CHS and was circumvented by injecting either neutrophils or hapten-primed CD8(+) T cells into ears of sensitized mice followed by specific hapten challenge. These results indicate that KC-directed neutrophil infiltration of hapten challenge sites is required for elicitation of CHS and suggest that neutrophils mediate recruitment of the hapten-specific CD8(+) T cells that subsequently produce cytokines mediating the hypersensitivity response.
Animals↗
Distinct roles for B7-1 and B7-2 determinants during priming of effector CD8+ Tc1 and regulatory CD4+ Th2 cells for contact hypersensitivity.
Contact hypersensitivity (CHS) is a CD8+ T cell-mediated response to hapten sensitization and challenge of the epidermis. Both the IFN-gamma-producing effector CD8+ T cells and the IL-4/IL-10-producing CD4+ T (Th2) cells that restrict the magnitude and duration of the response are primed by hapten-presenting Langerhans cells (hpLC). hpLC isolated from hapten-sensitized animals expressed high levels of B7-2 and lower levels of B7-1, suggesting the availability of each molecule to provide costimulation during CD8+ and CD4+ T cell priming for CHS. Anti-B7-2 Ab given during hapten sensitization inhibited effector CD8+ and regulatory CD4+ T cell development and the magnitude of the CHS response. Cytokine production by CD8+ and CD4+ T cells was reduced in anti-B7-2 Ab-treated animals, indicating that costimulation for T cell development was not compensated by hpLC-expressed B7-1. Anti-B7-1 Ab inhibited CHS and increased the number of Th2 cells primed during hapten sensitization without inhibiting development of the IFN-gamma-producing CD8+ T cells. Depletion of CD4+ T cells, however, abrogated the inhibitory effect of anti-B7-1 Ab on the CHS response, indicating the amplified Th2 response mediated this inhibition. These results indicate a requirement for B7-2 costimulation by effector CD8+ and regulatory CD4+ T cells during priming for CHS. The ability of anti-B7-1 Abs to amplify the regulatory CD4+ Th2 component and inhibit CHS suggests a strategy to inhibit unwanted CD8+ T cell-mediated immune responses to Ags in the skin.
Animals↗
Expression of chemokine genes during rejection and long-term acceptance of cardiac allografts.
Chemokines are cytokines with chemoattractant properties for leukocytes. They may play a critical role in directing leukocytes to graft sites and in amplifying intragraft inflammation during rejection. Previous studies have tested the intragraft expression of chemokine genes during the rejection of allogeneic skin grafts in mice. In the current study, we used a heterotopic heart transplant model in mice to test the intragraft expression of these genes in nonrejecting cardiac isografts, rejecting cardiac allografts, and cardiac allografts that were accepted due to immunosuppression with gallium nitrate. With the exception of low levels of interleukin-1beta and JE, intragraft expression of the the proinflammatory cytokine genes was not observed in either isografts or native heart. Two distinct patterns of chemokine mRNA were observed in the rejecting cardiac allografts. Intra-allograft expression of interleukin-1beta, interferon-gamma-inducible protein, JE, and KC was prominent by day 3 after transplantation. The expression of macrophage inflammatory protein (MIP)-1alpha, MIP-1beta, and regulated upon activation, normal T cell expressed and secreted (RANTES) was at low or undetectable levels at day 3 after transplantation but at high levels by day 8 after transplantation. Sixty days after transplantation, intra-allograft expression of chemokines in hearts from gallium nitrate-treated recipients indicated low levels of MIP-1alpha, MIP-1beta, and KC but high levels of interferon-gamma-inducible protein and RANTES.
Animals↗
Development of effector CD8+ T cells in contact hypersensitivity occurs independently of CD4+ T cells.
Contact hypersensitivity (CHS) is a T cell-mediated response to hapten sensitization of the epidermis. Recent results from this laboratory indicated that hapten sensitization induces two populations of hapten-reactive T cells: CD8+ T cells producing IFN-gamma, which mediate the response, and CD4+ T cells producing IL-4 and IL-10, which function to limit the magnitude and the duration of the response. In the current report we first examined the hapten-presenting cell priming each of these T cell populations and then examined the influence of CD4+ T cell priming on the development of the CD8+ effector T cells. Isolation of hapten-presenting Langerhans cells from the lymph nodes of oxazolone-sensitized mice and transfer to naive mice resulted in the induction of both the regulatory CD4+ and the effector CD8+ T populations. Both CD4+ and CD8+ T cells expressing high levels of the activation determinants CD11a and CD44 appeared in the lymph nodes 3 days after hapten sensitization. The CD8+ T cells producing IFN-gamma and mediating CHS responses following transfer to naive mice were restricted to the high CD44-expressing population. In vitro activation of hapten-immune CD8+ T cells resulted in very low amounts (3 U/ml) of IL-2 production, whereas production of IL-2 by immune CD4+ T cells was approximately 70-fold higher (208 U/ml). Despite this discrepancy in IL-2 production and the coincidental priming of CD4+ and CD8+ T cells by hapten-presenting Langerhans cells during hapten sensitization, the numbers of CD8+/high CD44-expressing T cells in the lymph nodes were nearly identical when CD4+ T cells were present or absent during hapten priming. These results indicate that coincidental priming of CD4+ (and CD8+) T cells by LC does not augment CD8+ T cell development in CHS.
Animals↗
T cell-dependent acceleration of chemoattractant cytokine gene expression during secondary rejection of allogeneic skin grafts.
Chemoattractant cytokines, chemokines, are likely to play a critical role in directing leukocytes to graft sites and in amplifying intragraft inflammation during rejection. Since second-set graft rejection occurs at an accelerated rate, we hypothesized that chemokine genes would be expressed earlier during secondary allograft rejection than during rejection of primary allografts. We have tested this hypothesis by using Northern blot analysis to compare intragraft expression levels of genes encoding interleukin (IL) 1beta and six chemokines during rejection of C57BL/6 skin grafts on naive and C57BL/6-sensitized BALB/c recipients. Expression levels of IL-1beta, interferon-gamma inducible protein, macrophage inflammatory protein-1 (MIP-1) alpha, and MIP-1beta genes were 10- to 17-fold higher on day 5 after transplantation in C57BL/6 grafts on C57BL/6-presensitized recipients than in C57BL/6 grafts on unprimed recipients. Intragraft expression of the chemokines regulated upon activation, normal T cell expressed and secreted (RANTES), during primary C57BL/6 graft rejection was virtually undetectable at day 7 after primary transplantation, but was expressed at high levels by day 5 after secondary transplantation. In third-party CBA/Ca allografts on unsensitized and C57BL/6-presensitized BALB/c mice, similar levels of IL-1beta, MIP-1alpha, and MIP-1beta expression were observed. High levels of RANTES and interferon-gamma inducible protein expression, however, were observed at day 5 after transplantation in CBA/Ca grafts on C57BL/6-presensitized recipients and correlated with accelerated rejection of the third-party grafts. Although T cells from C57BL/6-presensitized recipients did not express increased reactivity to CBA/Ca stimulator cells in vitro, serum antibodies from these recipients demonstrated reactivity to cells from CBA/Ca and A/J mice. When compared with transfer of unprimed cells, transfer of C57BL/6-primed lymphoid cells to sublethally irradiated BALB/c mice engrafted with C57BL/6 grafts resulted in increased intragraft proinflammatory cytokine gene expression. Deletion of T cells before transfer abrogated the increased intragraft expression of proinflammatory cytokine genes. Collectively, these results indicate that the accelerated expression of chemokine genes during second-set rejection of allogeneic skin grafts is mediated by immune T cells.
Animals↗
The anti-erythrocyte autoimmune response of NZB mice. Identification of two distinct autoantigens.
With age, New Zealand black (NZB) mice spontaneously develop anti-mouse red blood cell (RBC) autoantibodies resulting in the development of autoimmune haemolytic anemia (AIHA). Previously, we characterized a panel of monoclonal autoantibodies derived from unimmunized, adult NZB mice. One of these antibodies (G8) was shown to be pathogenic, inducing AIHA in a non-autoimmune-prone mouse strain (BALB/c). Using G8, and two other antibodies from our panel, we have characterized two distinct autoantigens on the surface of mouse RBCs. The autoantigen, historically referred to as antigen X (AgX), was found to be partially hidden on the surface of the mouse RBC because glycosidase treatment or mild digestion with proteinase K resulted in increased reactivity with autoantibodies. One of the monoclonal antibodies (3H5G1) was found to immunoprecipitate a 110,000 MW protein identified as the erythrocyte anion transporter (band 3) whereas the pathogenic antibody (G8) as well as a third monoclonal antibody (2E6m) were shown to immunoprecipitate a 60,000 MW protein that was not reactive with the anti-band 3 serum. Finally, we show that the autoantigen recognized by G8 is expressed on differentiated mouse erythroleukaemia (MEL) cells. The results suggest that a protein distinct from band 3 can serve as a target for AIHA in NZB mice.
Anemia, Hemolytic, Autoimmune↗
Can sensitized lymphocytes retain reactivity to inner ear antigens after retrieval from frozen storage?
Immune inner ear disease results in rapidly progressive, bilateral sensorineural hearing loss and is one of the few forms of sensorineural hearing loss that can be treated medically. The purpose of this study is to identify and preserve several populations of sensitized lymphocytes from patients with immune inner ear disease as a first step toward cloning autoreactive T cells, in order to study the pathogenesis of disease. Lymphocytes from four patients with high reactivity (stimulation index of 2.5 or greater) were placed in frozen storage. At 8 to 14 months they were thawed and restimulated. All four samples were viable. Two reacted again to inner ear homogenate, but with different intensities. Some lymphocytes sensitized to inner ear antigens can retain reactivity after frozen storage. This methodology may be useful to clone highly reactive T cells.
Adolescent↗
Induction of chemokine gene expression during allogeneic skin graft rejection.
The factors mediating trafficking of alloantigen-primed T cells and mononuclear phagocytes to the site of an allograft during the graft rejection process remain largely undefined. Based upon their demonstrated chemoattractant properties, chemokines may play a role in directing inflammatory cells to graft sites and initiate rejection. To begin to investigate the role of chemokines in graft rejection, we used Northern blot analysis to examine the temporal expression of 6 chemokine genes in murine allogeneic skin grafts disparate at the entire MHC and minor antigens and grafts with a disparity at either single class I or class II MHC determinants. Two general patterns of chemokine gene expression in each of the allografts were observed. Intragraft expression of 1 group of chemokine genes, including macrophage inflammatory protein-1alpha (MIP-1alpha), MIP-1beta, JE, and KC was observed at peak levels 3 days posttransplant in each of the 3 different allograft models. Expression of these genes in control isografts was at low levels, with the exception of JE, which was expressed at equivalent levels in all iso- and allografts for the first 4-5 days posttransplant, and KC, which was expressed at equivalent levels in C57BL/6 isografts and bm1 and bm12 allografts. A second group of chemokine genes, including RANTES (regulated upon activation normal T cell expressed and secreted) and IP-10 (interferon-gamma inducible protein), was expressed at low levels at early times after transplantation but at high levels 3-4 days before rejection of the allografts was complete. Isograft expression of RANTES and IP-10 was undetectable at the late time points. The results suggest that these 2 patterns of chemoattractant cytokine gene expression may be representative of the early inflammatory and the late T cell-mediated phases of the allograft rejection process, respectively.
Animals↗
Recipient polyclonal B cell activation and immunoglobulin production induced by priming with a retroviral superantigen.
The superantigen vSAG-7 (or MIs 1a) is a membrane glycoprotein encoded by the endogenous retrovirus mouse mammary tumor virus 7 (MMTV-7) and is highly stimulatory for V beta 6/CD4+ T cells. Priming of adult MMTV-7-negative mice with vSAG-7-expressing cells initially results in the activation of the peripheral V beta 6/CD4+ T cell compartment and is followed by T cell tolerance to the superantigen. During the course of tolerance induction the number of recipient B lymphocytes increases in the lymph nodes, but not the spleen, of vSAG-7-primed recipients. These B cells also express increased levels of class II MHC and present passively acquired superantigen. In this study we asked if these effects on the host B cell compartment are followed by the production of immunoglobulin. Priming of MMTV-7-negative BALB/c or CB.17 mice with vSAG-7-expressing cells from DBA/2 mice induced increases of both IgM and IgG2a in the serum. Use of Igh congenic CB.17 (IgMb) mice as recipients of the vSAG-7-presenting cells from DBA/2 (IgMa) donors indicated that the IgM and IgG produced were entirely of host origin. Priming with vSAG-7 also amplified (four- to fivefold) the antibody-producing cell response induced to a suboptimal dose of sheep RBC. Priming with purified B cells from vSAG-7 donors resulted in recipient V beta 6/CD4+ T cell activation and increased numbers of recipient B cells in the lymph nodes, but did not induce immunoglobulin production. In contrast, priming with purified CD8+ T cells resulted in increased quantities of serum IgM but not vSAG-7-reactive T cell activation or increased numbers of recipient B cells in the lymph nodes. These results indicate that the T cell activation and increased B cell number with upregulated class II MHC expression initially observed following vSAG-7 priming of adult MMTV-7-negative recipients are not linked to the induction of the recipient-derived immunoglobulin production.
Animals↗
T cell populations primed by hapten sensitization in contact sensitivity are distinguished by polarized patterns of cytokine production: interferon gamma-producing (Tc1) effector CD8+ T cells and interleukin (Il) 4/Il-10-producing (Th2) negative regulatory CD4+ T cells.
Contact hypersensitivity (CHS) is a T cell-mediated response to hapten sensitization of the epidermis. The roles of CD4+ and CD8+ T cells in CHS have remained unclear, however, as studies to define either subset as the T cells mediating CHS have provided conflicting results. The goal of this study was to correlate the in vivo function of CD4+ and CD8+ T cells in CHS with the cytokines produced by each T cell population. Antibody-mediated depletion of CD4+ T cells before sensitization of BALB/c mice with 2,4-dinitrofluorobenzene (DNFB) or oxazolone (Ox) resulted in increased and prolonged CHS responses, indicating CD4+ T cells as negative regulators of the response. Depletion of CD8+ T cells resulted in low or abrogated responses, indicating CD8+ T cells as the effector cells in CHS. Sensitization with DNFB or Ox induced lymph node cell populations of CD8+ T cells producing interferon (IFN)-gamma and no interleukin (Il) 4 or Il-10, and CD4+ T cells producing Il-4 and Il-10 and no or little detectable IFN-gamma. The polarized patterns of cytokine production were stimulated by culture of hapten-primed lymph node cells either on anti-T cell receptor antibody-coated wells or with semipurified Langerhans cells isolated from hapten-sensitized mice. Stimulation of cytokine production during culture of hapten-primed CD4+ or CD8+ T cells with Langerhans cells was hapten specific and restricted to class II or class I major histocompatibility complex, respectively. The induction of the CD4+ and CD8+ T cells producing the polarized patterns of cytokines was not restricted to BALB/c mice, as cells from Ox sensitized C57B1/6 and B10.D2 mice produced the same patterns. Collectively, these results expose the induction of two polarized and functionally opposing populations of T cells by hapten sensitization to induce CHS: IFN-gamma-producing effector CD8+ T cells and Il-4/Il-10-producing CD4+ T cells that negatively regulate the response.
Animals↗
Diversion of CD4+ T cell development from regulatory T helper to effector T helper cells alters the contact hypersensitivity response.
Cutaneous sensitization to reactive haptens and subsequent challenge results in a T cell-mediated response, contact hypersensitivity (CHS). Recent results from this laboratory have indicated that hapten sensitization induces two populations of reactive T cells: CD8+ T cells producing interferon (IFN)-gamma which mediate the response and CD4+ T cells producing interleukin (IL)-4 and IL-10 which negatively regulate the magnitude and duration of the response. Since CD4+ T cell development to either IFN-gamma-(Th1) or IL-4/IL-10-(Th2)-producing cells is dependent upon the cytokine environment during antigen priming, we hypothesized that CD4+ T cell induction in a Th1-promoting environment would not only alter the CD4+ T cell cytokine-producing phenotype but also the course of the CHS response. Administration of the Th1-promoting cytokine IL-12 during hapten sensitization resulted in a CHS response of greater magnitude following challenge and extended the duration of the response. In hapten-sensitized mice depleted of CD8+ T cells, treatment with IL-12 induced effector CD4+ T cells. Histological examination of challenged ear tissue from these mice indicated minimal edema and an acute mononuclear cell infiltration more typical of classical delayed-type hypersensitivity than CHS. Hapten-primed CD4+ T cells from IL-12 treated, sensitized mice produced IFN-gamma, but not IL-4 in response to T cell receptor-mediated stimulation. Use of neutralizing anti-IFN-gamma antibody indicated that IL-12 not only directly promoted Th1 development but also indirectly inhibited Th2 development through stimulation of IFN-gamma production at the time of hapten sensitization. Overall, these results demonstrate that diversion of CD4+ T cell development to Th1 effector cells rather than to Th2 cells alters the efferent nature of CHS and removes a primary regulatory mechanism of the immune response.
Animals↗
Interferon-gamma inducible protein (IP-10) expression is mediated by CD8+ T cells and is regulated by CD4+ T cells during the elicitation of contact hypersensitivity.
To investigate the potential roles of CD4+ and CD8+ T cells during contact hypersensitivity, we examined the T-cell-dependent expression of proinflammatory cytokine genes in the responses to dinitrofluorobenzene and oxazolone. Whole cell RNA was isolated from challenged ear tissue and analyzed for level of cytokine gene expression by Northern blot and densitometry analysis. Expression of interleukin 1 beta and the three chemokine genes (IP-10, JE, and KC) examined was dependent on the hapten dose used for sensitization and correlated with the immune response, i.e., ear swelling, elicited. Antibody-mediated depletion of CD8+ T cells before sensitization resulted in the absence of IP-10 expression following hapten challenge, indicating the ability of immune CD8+ T cells to mediate IP-10 expression. Depletion of CD4+ T cells resulted in higher levels of IP-10 and KC expression during elicitation of contact sensitivity, suggesting CD4+ T cells inhibit the expression of these proinflammatory genes. Depletion of CD4+ T cells resulted in contact hypersensitivity responses of higher magnitude and depletion of CD8+ T cells resulted in responses of lower magnitude. Transfer of CD8+ T-cell-depleted immune cells resulted in low, but detectable levels of IP-10 expression, indicating the ability of some oxazolone-immune CD4+ T cells to mediate IP-10 expression. These results indicate the differential induction of proinflammatory cytokine gene expression during elicitation of contact hypersensitivity in which expression of IP-10 is primarily mediated by immune CD8+ T cells and inhibited by immune CD4+ T cells.
Animals↗
Reconstitution of TCR alpha-chain expression in deletion mutants restores dinitrophenyl-specific/class I MHC-restricted suppressor molecule production.
A population of CD8+ T cells from dinitrobenzene sulfonate-primed mice produce soluble effector molecules that down-regulate the magnitude of dinitrophenol-specific contact hypersensitivity reactions. These soluble molecules express the binding specificity and serologic determinants of alpha/beta TCR. To examine the requirement for the TCR-alpha chain in the production of these molecules, we have cloned the alpha-chain gene used to encode the surface TCR of MTs 79.1, a T cell hybridoma producing a DNP/Kd-specific soluble suppressive molecule, and tested the ability of this gene to reconstitute the production of the regulatory molecule in TCR alpha-chain gene deletion mutants. Transfection and expression of the alpha-chain construct into an alpha-chain deletion mutant of the parental hybridoma that expressed the parental beta-chain gene resulted in reconstitution of both surface TCR expression and production of the soluble suppressive molecule. As with the molecule produced by the MTs 79.1 parental cells, the inhibitory activity produced by these alpha-chain gene transfectants was DNP-specific and expressed determinants bound by anti-V beta 8 Abs. Transfection of the alpha-chain gene construct into an alpha-/beta- chain gene deletion mutant did not restore the production of the soluble regulatory molecule. These results indicate that in addition to the TCR beta-chain gene, expression of the TCR alpha-chain gene is also required for the production of these molecules. Our results strongly support the hypothesis that some forms of immunosuppression are mediated by soluble forms of the TCR.
Animals↗
Transfer of endogenous retroviral superantigen from donor to recipient B cells following priming to induce peripheral T cell tolerance.
Endogenous retroviral superantigens such as vSAG-7 are highly stimulatory for T cells through interaction with the T cell receptor on the basis of V beta usage. Priming of adult MMTV 7-negative mice with vSAG-7-expressing cells has been shown to result in peripheral V beta 6/CD4+ T cell activation followed by tolerance to further interaction with the superantigen. The goal of the current study was to examine the cells presenting vSAG-7 during this initial burst of in vivo T cell activation. Priming of MMTV 7-negative BALB/c (H-2d) mice with DBA/2 (H-2d, MMTV 7+) spleen cells resulted in a 5- to 12-fold increase in the number of B cells in the lymph nodes. These B cells expressed increased levels of I-A and I-E class II MHC determinants. Use of MMTV 7-negative CB.17 (H-2d, Ighb) mice as recipients of DBA/2 (Igha) cells indicated that the increased number of B cells was of host, rather than donor, origin. The number of donor-derived (IgM/B220+) B cells observed during the course of vSAG-7-reactive V beta 6/CD4+ T cell activation was very low. Proliferation of unprimed T cells from MMTV 7-negative mice was induced during coculture with B cells from the lymph nodes of vSAG-7-primed recipients and was blocked by anti-class II MHC antibodies, as well as by an anti-vSAG-7 antibody. Highly purified host B cells from vSAG-7-primed recipients specifically stimulated the blastogenesis of V beta 6/CD4+ T cells in vitro. Collectively, the results indicate that following priming to induce peripheral tolerance, vSAG-7 is transferred from donor cells to class II MHC determinants on recipient B cells and is presented to the T cell repertoire by the autologous B cells.
Animals↗
T cell activation is not a prerequisite for peripheral tolerance induction to Mls 1a.
T cell interaction with endogenous retroviral superantigens in vivo results in either deletion of the reactive T cells or their transition to a state of unresponsiveness. We show here that introducing cells expressing the endogenous superantigen Mls 1a into an Mls 1b environment results in the induction of an anergic state with little or no depletion of V beta 6/CD4+ T cell from the peripheral T cell repertoire. Removal of B cells from the priming innoculum abrogates the induction of tolerance, indicating that presentation of Mls 1a by B cells induced the tolerance observed. The tolerant T cells are unable to respond to either presentation of Mls 1a on spleen cells or cross-linking anti-T cell receptor antibody in vitro. Although large increases in the cell size and numbers of reactive T cells are observed 2-3 days after priming with Mls 1a-presenting cells, this activation is not a requirement for the induction of tolerance because irradiated Mls 1a-presenting cells retained the ability to induce tolerance without these changes in the reactive T cell population. Furthermore, providing host T cells with Mls 1a and a costimulatory signal, in the form of high levels of the B7 determinant on the donor cells, did not circumvent the induction of tolerance. Collectively, these results indicate that the transition to an anergic state following interaction with endogenous superantigen in vivo is not dependent upon the activation of the reactive T cells.
Animals↗