MHC-linked immune response suppression mediated by T cells bearing I-A-encoded determinants

The immune response to chicken egg-white lysozyme (HEL) is actively and specifically regulated by antigen-specific T cell-mediated suppression in mice bearing the H-2b haplotype; the suppression is therefore MHC-linked. In this report, we propose a possible mechanism for MHC-linked suppression of HEL-helper T cells based on expression of I region-encoded cell surface determinants. We determined whether inhibition of anti-HEL antibody responses correlated with expression of serologically detectable I-A-encoded cell surface determinants by antigen-specific helper, suppressor-inducer, or suppressor-effector T cells. It was observed that HEL-suppressor-effector T cells, but not helper or suppressor-inducer T cells, were eliminated after treatment with anti-I-Ab antibody and complement. Furthermore, suppressor-effector T cells co-express Thy-1, Lyt-2, and I-A cell surface antigens. These results raise the possibility that HEL-specific helper T cells become functionally inhibited after recognition of HEL and I-A alloantigen displayed by suppressor-effector T cells. Thus, the interaction between helper and suppressor T cells may be analogous to the mechanism of T cell-B cell interaction.     

Insulin-specific suppressor T cell factors

Murine antibody responses to heterologous insulins are controlled by MHC-linked immune response genes. Although nonresponder mice fail to make antibody when injected with nonimmunogenic variants of insulin, we have recently shown that nonimmunogenic variants stimulate radioresistant, Lyt- 1+2- helper T cells that support secondary antibody responses. However, the helper activity can not be detected unless dominant, radiosensitive Lyt-1-2+, I-J+ suppressor T cells are removed. In this paper we report that extracts of primed Lyt-2+ suppressor T cells contain insulin-specific suppressor factors (TsF) that are capable of replacing the activity of suppressor T cells in vitro. The activity of these factors is restricted by MHC-linked genes that map to the I-J region, and immunoadsorption studies indicated that they bind antigen and bear I-J-encoded determinants. Insulin-specific TsF consists of at least two chains, one-bearing I-J and the other the antigen-binding site. Furthermore, mixing of isolated chains from different strains of mice indicates that the antigenic specificity is determined by the antigen-binding chain and the MHC restriction by the H-2 haplotype of the source of the non-antigen-binding, I-J+ chain. Moreover, mixtures containing antigen-binding chain from allogeneic cell donors and I-J+ chain from responder cell donors have activity in cultures containing responder lymphocytes. This suggests that preferential activation of suppressor T cells, rather than differential sensitivity to suppression, results in the nonresponder phenotype to insulin.     

Feedback suppression of the immune response in vivo. III. Lyt-1+ B cells are suppressor-inducer cells

We previously demonstrated that injection of a high dose (4 X 10(9] of sheep erythrocytes (SRBC) into C57BL/6 mice results in the generation of splenic B cells (plastic nonadherent, Thy-1- and Ig+) which, when transferred to normal syngeneic recipients, subsequently induce antigen-specific suppressor T cells to suppress the recipient's plaque-forming cell (PFC) responses to SRBC. In the present study we characterized the suppressor-inducer B cells phenotypically. Cytotoxic treatment of the donor's immune spleen cells with anti-Lyt-1 antibody plus complement (C'), but not with anti-Lyt-2 antibody plus C', relieved the suppression of PFC responses in recipients. The FcRr+ population separated by EA-rosette formation showed enriched suppressor-inducing activity, whereas the FcRr- population showed no activity. Our findings, taken together with the previous ones, suggest that suppressor-inducer cells are Thy-1-, Lyt-1+, Lyt-2-, FcRr+, and Ig+.     

Identification of suppressor T cells in virgin non-responder spleen cells responsible for primary unresponsiveness to L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT)

T cell subsets that regulate antibody responses to L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT) in mice that are Ir gene non-responders have been further characterized. We previously defined several T cell subsets in GAT-primed non-responder mice. The Lyt-2+ suppressor-effector T cells suppress responses to GAT and GAT complexed to methylated BSA (GAT-MBSA). The Lyt-1+ cell population is complex and can be separated into I-J- Th cells, which support responses to GAT and GAT-MBSA. After priming, the Lyt-1+, I-J+ cell population contains suppressor-inducer cells that activate precursors of suppressor-effector cells to suppress responses to GAT and GAT-MBSA as well as Ts cells that directly inhibit responses to GAT but not GAT-MBSA. By contrast, the Lyt-1+ cells from virgin mice contain only cells that directly suppress responses to GAT but not GAT-MBSA. The major question addressed in the present studies was whether the Lyt-1+, I-J+ Ts cells in virgin and primed mice and the suppressor-inducer cells in GAT-primed mice were functionally and serologically distinct subsets. The studies used mAb and panning procedures to separate cell populations and inhibition of PFC cell responses to functionally define the activity of the cell populations. We used the following two mAb that were raised by immunizing rats with GAT-specific suppressor factors: 1248A4.10 (known to react with suppressor-inducer cells) and 1248A4.3, another reagent from the same fusion. Lyt-1+ cells from virgin spleens contained Ts cells that were A4.10-, A4.3+ and no suppressor-inducer T cells, whereas Lyt-1+ cells from GAT-primed spleens contained Ts cells that were A4.10-, A4.3+ as well as A4.10+, A4.3- suppressor-inducer cells. Thus, the Lyt1+, I-J+ cell subset can be divided into two functionally and serologically distinct subsets, direct Ts cells (1248A4.3+), which suppress responses to GAT but not GAT-MBSA, and GAT-primed suppressor-inducer T cells (1248A4.10+).     

IgE-binding factors from mouse T lymphocytes. III. Role of antigen-specific suppressor T cells in the formation of IgE-suppressive factor

BDF1 mice were given three i.v. injections of ovalbumin (OA) to induce antigen-specific suppressor T cells. Incubation of spleen cells of OA-treated mice with homologous antigen resulted in the formation of IgE-suppressive factor. This factor was not derived from antigen-specific suppressor T cells, but suppressor T cells were essential for determining the nature of IgE-binding factors formed. In the spleen cells of OA-treated mice, antigenic stimulation of antigen-primed Lyt-1+ (helper) T cells resulted in the formation of inducers of IgE-binding factor, whereas Lyt-2+, I-J+ T cells released glycosylation-inhibiting factor (GIF), and these two factors, in combination, induced unprimed Lyt-1+ T cells to form IgE-suppressive factor. The role of GIF is to inhibit the assembly of N-linked oligosaccharides on IgE-binding factors during their biosynthesis, and thereby provide them with a biologic activity: suppression of the IgE response. Under the experimental conditions employed, GIF was released spontaneously from antigen-specific suppressor T cells. However, antigenic stimulation of the cells enhanced the release of the factor. GIF from antigen-specific suppressor T cells has a m.w. of 25,000 to 30,000, as estimated by using gel filtration, binds to anti-I-J alloantibodies and to a monoclonal antibody specific for lipomodulin, and has affinity for specific antigen. The possible relationship between antigen-specific GIF and antigen-specific suppressor factors is discussed.     

T cell regulation of B cell activation: antigen-specific and antigen-nonspecific suppressor pathways are mediated by distinct T cell subpopulations

The present studies were carried out to characterize the cellular events involved in the induction and function of carrier-specific Ts cells, which selectively regulate the generation of IgG responses by Lyb-5- B cells. It was demonstrated that this regulation is in fact mediated by two distinct suppressor pathways. In one pathway, carrier-primed Lyt-1 + 2 - Ts cells are specifically activated by in vitro reexposure to the priming antigen. After this specific activation, these Lyt-1 + 2 - Ts cells are able to suppress IgG responses in an antigen-nonspecific manner. This suppression requires the participation of unprimed Lyt-1 - 2 + T cells, and is effective in both the early and the late phases of antibody responses. A second suppressor pathway requires the antigen-specific activation of primed Lyt-1 - 2 + Ts cells. Suppression of antibody responses by activated Lyt-1 - 2 + Ts cells is highly carrier specific, in contrast to the nonspecific effector function of Lyt-1 + 2 - Ts cells, appears to act without requirement for additional T cell populations; and is effective only early in the course of the antibody response. Thus, it appears that two Ts cell populations may function through distinct mechanisms to regulate the generation of IgG Lyb-5- B cell responses.     

Two defects in old New Zealand Black mice are involved in the loss of low-dose paralysis to type III pneumococcal polysaccharide

Treatment of normal mice with a subimmunogenic dose of type III pneumococcal polysaccharide (SSS-III) results in the development of an antigen-specific state of unresponsiveness termed low-dose paralysis. This unresponsiveness is mediated by T suppressor cells and can be transferred by Lyt-2+ T cells, but not by L3T4+ T cells, obtained 18 hr after priming. As autoimmune New Zealand Black (NZB) mice age, there is a progressive decrease in low-dose paralysis to SSS-III. The defect in older NZB mice resulting in decreased suppressive activity was investigated by transferring primed Lyt-2+ T cells from young into old mice, and vice versa. Enlarged Lyt-2+ T cells from old NZB mice could not suppress the SSS-III response of young recipients. However, Lyt-2+ T cells of normal cell size were efficient in inhibiting the antibody response upon transfer. Primed Lyt-2+ T cells from young NZB mice did not affect the response of old recipients, but effectively suppressed the response of young mice. These results suggest that there are two defects involved in the decline of low-dose paralysis to SSS-III in aging NZB mice: Enlarged Lyt-2+ T cells may lose their ability to function as mediators of suppression; and B cells may become resistant to T cell-mediated suppression.     

Alloantigen-specific T suppressor-inducer and T suppressor-effector cells can be activated despite blocking the IL-2 receptor

To determine IL-2 requirement for activation of suppressor cells, PBMC were primed in one-way MLR in the presence of 10 micrograms/ml anti-IL-2R beta-chain antibody 2A3 (CD25) or control antibody, then irradiated and added as regulators in a fresh MLR. Cells primed in the presence of antibody 2A3 suppressed the proliferative response to fresh autologous lymphocytes to specific alloantigen but had no effect on the response to cells from third party donors. Priming in the presence of an antibody of irrelevant specificity induced only limited suppressor activity. Activated suppressor cells did not show cytolytic activity specific for the stimulators when tested at the time of the suppressor cell assay. To identify the subset(s) responsible for suppression, cells primed in the presence of antibody 2A3 were separated into CD4+/CD45RA+, CD4+/CD45RA-, and CD8+ subsets, which were irradiated and then tested. The suppressive activity was found predominantly in the CD4+/CD45RA+ subset, whereas CD8+ cells had some activity and CD4+/CD45RA- cells had none. No subset suppressed the response of autologous cells to third-party cells. When primed CD4+/CD45RA+ cells were cocultured with fresh autologous lymphocytes depleted of CD8+ cells, no suppression was observed, indicating that, although the CD4+/CD45RA+ cells can function as inducers of suppressors, they cannot function as suppressor-effectors. Conversely, CD8+ cells activated in MLR in the presence of 2A3 caused suppression, regardless of whether the fresh autologous responder population contained CD8+ cells. CD4+/CD45RA+ and CD8+ subsets isolated after priming in the presence of 2A3 also demonstrated Ag-specific suppression in the generation of cytotoxic T lymphocytes whereas CD4+/CD45RA- cells had no activity. Our data are consistent with the model that suppression of alloreactivity requires the cooperation of two types of cells, a CD4+/CD45RA+ suppressor-inducer and a CD8+ suppressor-effector population. Activated Tsi and fresh Tse or activated Tse alone can suppress lymphocyte proliferation and generation of CTL in response to specific Ag. Activation of Ag-specific T suppressor-inducer and T suppressor-effector cells appears to be relatively IL-2 independent and presumably require one or more other growth factors.     

T cell subsets regulating antibody responses to L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT) in virgin and immunized nonresponder mice

T cell subsets from virgin and immunized mice, which are Ir gene controlled nonresponders to GAT, which regulate antibody responses to GAT have been characterized. Virgin nonresponder B10.Q B cells develop GAT-specific antibody responses to GAT, B10.Q GAT-M phi, and GAT-MBSA when cultured with virgin or GAT-primed Lyt-1+, I-J-, Qa1- B10.Q helper T cells. Virgin T cells are radiosensitive, whereas immune T cells are radioresistant (750 R); qualitatively identical helper activity is obtained with T cells from mice immunized with soluble GAT, B10.Q GAT-M phi, and GAT-MBSA. Responses to GAT and GAT-M phi are not observed when virgin or GAT-primed Lyt-1+, I-J+, Qal+ T cells are added to culture of virgin or GAT-primed Lyt-1+, I-J-, Qa1- helper T cells and virgin B cells; the GAT-specific response to GAT-MBSA is intact. The Lyt-1+, I-J+, Qa1+ T cells from mice primed with GAT, GAT-M phi, and GAT-MBSA were qualitatively identical in mediating this suppression. Virgin Lyt-2+ T cells have no suppressive activity alone or with virgin Lyt-1+, I-J+, Qa1+ T cells, whereas responses to GAT, GAT-M phi, and GAT-MBSA are suppressed in cultures of GAT-primed helper T cells containing GAT-primed Lyt-2+ T cells (with or without GAT-primed Lyt-1+, I-J+, Qa1+ T cells). Suppression of responses to GAT-MBSA in cultures of GAT-M phi-primed helper T cells requires both GAT-M phi-primed Lyt-1+, I-J+, Qa1+ T cells and Lyt-2+ T cells; the Lyt-1+, I-J+, Qa1+ T cells appear to function as inducer cells in this case. In cultures containing GAT-MBSA-primed helper T cells, either GAT-MBSA-primed Lyt-1+, I-J+, Qa1+ or Lyt-2+ T cells suppress responses to GAT and GAT-M phi; under no circumstances are responses to GAT-MBSA suppressed by GAT-MBSA-primed regulatory T cells. This regulation of antibody responses to GAT by suppressor T cells is discussed in the context of the involvement of suppressor T cells in responses to antigens under Ir control, and of the evidence that nonresponsiveness to GAT is not due to a defect in the T cell repertoire, but rather is due to an imbalance in the activation of suppressor vs helper T cells.     

Induction of T15-specific suppressor T cells in mice with the CBA/N defect by neonatal injection with anti-T15 idiotype antibody

Mice with the CBA/N defect (xid) are unresponsive to phosphorylcholine (PC), To determine whether idiotype-specific suppressor T cells can also be generated in these defective mice, defective (CBA/N X BALB/c)F1 male and nondefective (CBA/N X BALB/c)F1 female or (BALB/c X CBA/N)F1 male mice were neonatally injected with antibodies specific for the major idiotype of anti-PC antibody, i.e., anti-TEPC-15 idiotype (T15id) antibody. Suppressor cell activity was examined by co-culturing spleen cells from neonatally treated F1 mice with spleen cells of normal nondefective F1 mice in the presence of antigen. Spleen cells from defective (CBA/NM X BALB/c)F1 mice treated with anti-T15id antibody demonstrated a level of suppressor activity (greater than 83% suppression) comparable to that of similarly treated nondefective F1 mice. This suppression was specific for the T15id of anti-PC response, and a Lyt-1-2+-bearing T cell population appeared to be responsible for the active suppression. These suppressor T cells recognized T15 but not PC, based on a functional absorption test. These results indicate that the CBA/N defects, including the deficiency in the anti-PC response by B lymphocytes and a possible T cell defect, do not influence the generation of T15id-specific suppressor T cells by neonatal injection with anti-T15id antibody.     

Regulation of immune responses by T cell subsets. Role of helper and suppressor T cells in the development and expression of MHC-restricted antibody responses to L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT) by (responder X responder)F1 spleen cells

The roles of helper and suppressor T cells in the development and expression of antibody responses to GAT were studied in (responder X responder)F1 mice immunized with parental GAT-M phi. Spleen cells from (B10 X B10.D2)F1 mice primed in vivo with B10 or B10.D2 GAT-M phi developed secondary in vitro plaque-forming cell (PFC) responses only when stimulated by GAT-M phi syngeneic with the GAT-M phi used for in vivo priming. By contrast, virgin F1 spleen cells developed comparable primary PFC responses to both parental GAT-M phi Co-culture of T cells from (B10 X B10.D2)F1 mice primed in vivo by B10 GAT-M phi with virgin (B10 X B10.D2)F1 spleen cells demonstrated the presence of suppressor cells that inhibited the primary response of virgin spleen cells stimulated by B10.D2 GAT-M phi. Spleen cells from (B10 X B10.D2)F1 mice primed in vivo with B10.D2 GAT-M phi had suppressor T cells that suppressed primary responses stimulated by B10 GAT-M phi. The suppressor T cell mechanism was composed of at least two regulatory T cell subsets. Suppressor-inducer T cells were Lyt-2-, I-J+ and must be derived from immune spleen cells. Suppressor-effector T cells can be derived from virgin or immune spleens and were Lyt-2+ cells. When the suppressor mechanism was disabled by treatment with 1000 rad gamma irradiation or removal of Lyt-2+ cells, Lyt-2-helper T cells from (B10 X B10.D2)F1 mice primed with B10 GAT-M phi provided radioresistant help to virgin F1 B cells stimulated by B10 but not B10.D2 GAT-M phi. Suppressor inducer Lyt-2-,I-J+ cells from B10 GAT-M phi-primed (B10 X B10.D2)F1 mice were separated from the primed Lyt-2-,I-J-helper T cells. In the presence of Lyt-2+ suppressor effector cells, the Lyt-2-,I-J+ suppressor-inducer suppressed the primary response of virgin spleen or virgin T plus B cells stimulated by both B10 and B10.D2 GAT-M phi. Therefore, suppressor T cells were able to suppress primary but not secondary GAT-specific PFC responses stimulated by either parental GAT-M phi. These results showed that immunization of (responder X responder)F1 mice with parental GAT-M phi results in the development of antigen-specific helper and suppressor T cells. The primed helper T cells were radioresistant and were genetically restricted to interact with GAT in association with the major histocompatibility complex antigens of the M phi used for in vivo priming.(ABSTRACT TRUNCATED AT 400 WORDS)     

T cell subsets in (responder x nonresponder)F1 mice regulating antibody responses to L-glutamic acid60-L-alanine30-L-tyrosine (GAT)

Immune responses to GAT are controlled by H-2-linked Ir genes; soluble GAT stimulates antibody responses in responder mice (H-2b) but not in nonresponder mice (H-2q). In nonresponder mice, soluble GAT stimulates suppressor T cells that preempt function of helper T cells. After immunization with soluble GAT, spleen cells from (responder x nonresponder: H-2b X H-2q)F1 mice develop antibody responses to responder H-2b GAT-M phi but not to nonresponder H-2q GAT-M phi. This failure of immune F1 spleen cells to respond is due to an active suppressor T cell mechanism that is activated by H-2q, but not H-2b, GAT-M phi and involves two regulatory T cell subsets. Suppressor-inducer T cells are immune radiosensitive Lyt-1 +2-, I-A-, I-J+, Qa-1+ cells. Suppressor-effector T cells can be derived from virgin or immune spleens and are radiosensitive Lyt-1-2+, I-A-, I-J+, Qa-1+ cells. This suppressor mechanism can suppress responses of virgin or immune F1 helper T cells and B cells. Helper T cells specific for H-2b GAT-M phi are easily detected in F1 mice after immunization with soluble GAT; helper T cells specific for H-2q GAT-M phi are demonstrated after elimination of the suppressor-inducer and -effector cells. These helper T cells are radioresistant Lyt-1+2-, I-A+, I-J-, Qa-1- cells. These data indicate that the Ir gene defect in responses to GAT is not due to a failure of nonresponder M phi to present GAT and most likely is not due to a defective T cell repertoire, because the relevant helper T cells are primed in F1 mice by soluble GAT and can be demonstrated when suppressor cells are removed. These data are discussed in the context of mechanisms for expression of Ir gene function in responses to GAT, especially the balance between stimulation of helper vs suppressor T cells.     

T and B cells induce macrophages which suppress proliferation but not lymphokine secretion

In vitro culture of mouse spleen cells for 2 days or more leads to the production of adherent, phagocytic, Thy-1-, Ia+, Lyt-2- cells ("suppressor macrophages") which strongly inhibit the proliferative response of T and B lymphocytes to a variety of stimuli: mitogens, specific antigens, and antigen-nonspecific growth factors. Suppressive activity fails to develop, however, in cultured spleen cells from which nonadherent cells have been removed before the initial 48-hr incubation, and only partial suppression is obtained from cell suspensions from which T cells have been depleted before culture. We find that the requirement for nonadherent cells can be replaced by graded doses of lymphocytes. Lyt-2- and Lyt-2+ T cells are about equally potent in inducing suppressive activity in nonadherent cells. Surprisingly, B cells (containing fewer than 0.1% contaminating T cells) are also able to induce suppression in this system. The suppression induced includes both indomethacin-sensitive and indomethacin-resistant components. Interestingly, not all stages of mitogen-induced T-cell activation are blocked by these adherent cells: proliferation is inhibited, but production of interleukin 2 (IL-2) and interleukin 3 (IL-3) is unaffected.     

Role of L3T4 antigen in the activation of various functions of Lyt-1+2- T cells against vaccinia virus

The present study defines assay systems for vaccinia virus-reactive Lyt-1+2- T cells mediating various functions and investigates the positivity of L3T4 antigen on these Lyt-1+2- T cells as well as the role of L3T4 antigen in the activation of these T cells with respect to their functions. C3H/He mice were immunized against vaccinia virus by inoculating viable virus intraperitoneally (i.p.). Anti-vaccinia virus reactivity in lymphoid cells from these immunized mice was assessed by proliferative response, helper T cell activities involved in cytotoxic T lymphocyte (CTL) and B cell (antibody) responses, delayed type-hypersensitivity (DTH) response, and production of lymphokines such as interleukin 2 (IL2) and macrophage-activating factor (MAF). The results demonstrate that all of the above anti-vaccinia virus responses were mediated by Lyt-1+2- T cells and that these Lyt-1+2- T cells expressed L3T4 antigens on their cell surfaces. Moreover, such anti-vaccinia Lyt-1+2- T cell responses were inhibited in the presence of anti-L3T4 antigen antibody. These results indicate that there is a reciprocal relationship between Lyt-2 and L3T4 markers, and that L3T4 antigen is closely related to the activation of various functions of anti-vaccinia virus Lyt-1+2- T cells.     

The nature of the interaction between suppressor and helper T cells in the response to LDHB

Purified Lyt-1+2+ T cells were depleted of alloreactive cells by BUdR and light treatment, and then were primed in vitro against LDHB presented on allogeneic APC. Such cells could be restimulated by LDHB on the same allogeneic APC, but not by LDHB on APC syngeneic with the T cells. The restimulated T cells suppressed the proliferative response of Lyt-1+2- T cells primed and restimulated by the same antigen. The suppression, which was antigen specific, occurred after a 6-hr co-culture of the suppressor (Tse) and proliferating helper (Th) cells. The successful interaction (as measured by suppression) between allogeneic Th and Tse cells was found to be determined by the restriction specificity but not the MHC haplotype of Th cells, and the MHC haplotype but not the restriction specificity of Tse cells. Thus, suppression occurred only when the Tse cells carried genes controlling the MHC molecules that served as restriction elements for antigen recognition by the Th cells. No evidence could be obtained for the participation of APC in the Tse-Th interaction. The data suggest the interaction is based on the recognition by the Th cell of the antigen presented in the context of MHC molecules controlled by the Tse cell.     

Immunosuppressive effects of glycosylation inhibiting factor on the IgE and IgG antibody response

Glycosylation inhibiting factor (GIF) was purified from culture filtrates of a T cell hybridoma, 23A4, by affinity chromatography on anti-lipomodulin Sepharose. The factor exhibited phospholipase inhibitory activity upon dephosphorylation. Immunization of BDF1 mice with aluminum hydroxide gel (alum)-absorbed dinitrophenyl derivatives of ovalbumin (DNP-OA) resulted in persistent IgE and IgG antibody formation. However, repeated injections of the affinity-purified GIF into the DNP-OA-primed mice beginning on the day of priming prevented the primary anti-hapten antibody responses of both the IgE and the IgG1 isotypes. Treatment with GIF also diminished on-going IgE antibody formation in the DNP-OA-primed mice. The treatment changed the nature of IgE-binding factors formed by BDF1 spleen cells. Incubation of spleen cells from OA + alum-primed mice with OA resulted in the formation of IgE-potentiating factor, whereas spleen cells of OA-primed, GIF-treated mice formed IgE-suppressive factor upon antigenic stimulation. It was also found that Lyt-2+ T cells in the OA-primed, GIF-treated mouse spleen cells released GIF, which had affinity for OA and bore I-Jb determinant(s). Transfer of a Lyt-1+ cell-depleted fraction of the OA-primed, GIF-treated mouse spleen cells into naive syngeneic animals resulted in suppression of the primary anti-DNP IgE antibody response of the recipients to alum-absorbed DNP-OA, but failed to affect the anti-DNP antibody response to DNP-keyhole limpet hemocyanin. The results indicate that GIF treatment during the primary response to OA facilitated the generation of antigen-specific suppressor T cells.     

Regulation of the secondary in vitro antibody response by endogenous natural killer cells: kinetics, isotype preference, and non-identity with T suppressor cells

Our previous studies had demonstrated that depletion of endogenous natural killer (NK) cells resulted in an augmented primary antibody response in vivo and in vitro. We have now examined the effect of NK cell depletion on the in vitro secondary response to antigen. Treatment of primed murine spleen cells with anti-NK-1.1 allo-antibody and complement before culture resulted in a significant increase in the magnitude of the antigen-specific plaque-forming cell (PFC) response. This treatment did not affect the proportions of Lyt-2+, L3T4+, or sIg+ cells in the population, however, indicating that the augmentation in PFC was not due to changes in the ratio of T to B cells. Removal of endogenous NK cells had a greater effect on the IgG (indirect) PFC response (100 to 200% increase) than on the IgM (direct) PFC response (25 to 50% increase). In contrast, removal of Lyt-2+ cells before culture affected the IgM and IgG responses similarly. Moreover, the kinetics of augmentation differed between cultures depleted of Lyt-2+ cells and those depleted of NK-1.1+ cells. NK cells appeared to act earlier in the response than did T suppressor cells. The NK-1.1+ cells involved in antibody regulation were not involved in the generation of the in vitro derived T suppressor cells. The conclusion that the regulation of the antibody response by NK-1.1+ cells is distinct from that involving T suppressor cells was confirmed in experiments in which removal of both regulatory cell populations resulted in an increase in PFC that was greater than in cultures depleted of either NK or T suppressor cells.     

Role of self carriers in the immune response and tolerance. VIII. Suppression of the MOPC-104E idiotypic response by idiotype-modified self, but not by dextran-modified self

We have investigated the suppression of the anti-dextran B1355S immune response using our model of modified self. The anti-dextran response is idiotypically well defined in BALB/c mice. This system enables us to examine the contribution of various predominant idiotypes to the antibody response under conditions of suppression by antigen or by idiotype-specific suppressor cells. Our results demonstrate that the total anti-dextran response can be inhibited by pretreatment of animals with dextran-coupled syngeneic spleen cells; however, the representation of major idiotypes constituting this response are not reduced in percentage. In contrast, pretreatment of mice with MOPC-104E-coupled spleen cells leads to a specific suppression of the private IdI-104E idiotype. The total anti-dextran response remains unchanged, as well as proportions of other major idiotypes known (IdI-588 and IdX). This suppression is mediated by Thy-1.2+, Lyt-2.2+ T cells, as demonstrated by adoptive transfer assays. This system will allow the molecular dissection of the regulation of an idiotypically well-defined system for the suppression by either antigen- or idiotype-specific suppressor T cells.     

Antigen-induced T suppressor cells regulate the autoreactive T helper-B cell interaction

The T suppressor (Ts) cell population that functions to regulate antigen-specific MHC-restricted T helper (Th)-B cell interactions also regulates the activation of B cells by cloned autoreactive Th cells. Activated Ts cells were generated by in vivo priming and restimulation in vitro with high concentrations of the specific priming antigen. Once generated, this Ts population inhibits the Th-dependent activation of primed B cells by both antigen-specific and autoreactive T cells in an antigen-nonspecific manner. This suppression requires the participation of both Lyt-1+2- and Lyt-1-2+ T cells. It was also demonstrated that accessory cells were required for the induction of Ts cells. Moreover, the generation of suppression was MHC-restricted and required the recognition by T cells of Ia antigens on accessory cells. These studies demonstrate that the same or a very similar Ts cell population can function to inhibit the activation of B cells by antigen-specific as well as autoreactive T cells.     

In vitro T cell-mediated killing of Pseudomonas aeruginosa. IV. Nonresponsiveness in polysaccharide-immunized BALB/c mice is attributable to vinblastine-sensitive suppressor T cells

We reported previously that BALB/c mice immunized with a polysaccharide (PS) antigen isolated from immunotype 1 Pseudomonas aeruginosa and vinblastine sulfate develop T cell-mediated protective immunity, despite their failure to produce specific antibody. In vitro, Lyt-1-,2+, I-J+ T cells from vinblastine- and PS-immunized mice kill P. aeruginosa by secretion of a bactericidal lymphokine. BALB/c mice immunized with PS alone generate neither protective antibodies nor a protective T cell response. The current studies indicate that T cells from mice immunized with PS alone significantly suppress the bactericidal activity of T cells from mice immunized with vinblastine and PS. The suppressor T cells are of the same Lyt-1-,2+, I-J+ phenotype as the bactericidal T cells. Suppression is mediated by a soluble product of these suppressor T cells which both inhibits T cell proliferation and interferes with the production or release of the bactericidal lymphokine. Cyclophosphamide, used in other systems to remove suppressor T cells, fails to enhance bacterial killing and does not inhibit suppressor cell activity. These studies indicate that immunization with PS elicits responses in two functionally distinct subgroups of Lyt-1-,2+, I-J+ T cells, and that these cells are distinguishable by their sensitivity to vinblastine sulfate.