Genetically Restricted Research Articles

Genetic regulation of the immune response to hepatitis B surface antigen (HBsAg). V. T cell proliferative response and cellular interactions.

We previously demonstrated that in vivo antibody production to HBsAg in the mouse is regulated by at least two immune response (Ir) genes mapping in the I-A (HBs-Ir-1) and I-C (HBs-Ir-2) subregions of the H-2 locus. To confirm that H-2-linked Ir genes regulate the immune response to HBsAg at the T cell level and to determine if the same Ir genes function in T cell activation as in B cell activation, the HBsAg-specific T cell responses of H-2 congenic and intra-H-2 recombinant strains were analyzed. HBsAg-specific T cell proliferation, IL 2 production, and the surface marker phenotype of the proliferating T cells were evaluated. Additionally, T cell-antigen-presenting cell (APC) interactions were examined with respect to genetic restriction and the role of Ia molecules in HBsAg presentation. The HBsAg-specific T cell proliferative responses of H-2 congenic and intra-H-2 recombinant strains generally paralleled in vivo anti-HBs production in terms of the Ir genes involved, the hierarchy of responses status among H-2 haplotypes, antigen specificity, and kinetics. However, the correlation was not absolute in that several strains capable of producing group-specific anti-HBs in vivo did not demonstrate a group-specific T cell proliferative response to HBsAg. The proliferative responses to subtype- and group-specific determinants of HBsAg were mediated by Thy-1+, Lyt-1+2- T cells, and a possible suppressive role for Lyt-1-2+ T cells was observed. In addition to T cell proliferation, HBsAg-specific T cell activation could be measured in terms of IL 2 production, because anti-HBs responder but not nonresponder HBs-Ag-primed T cells quantitatively produced Il 2 in vitro. Finally, the T cell proliferative response to HBsAg was APC dependent and genetically restricted in that responder but not nonresponder parental APC could reconstitute the T cell response of (responder X nonresponder)F1 mice, and Ia molecules encoded in both the I-A and I-E subregion are involved in HBsAg-presenting cell function.

Cell contact-mediated macrophage activation for antileishmanial defense. II. Identification of effector cell phenotype and genetic restriction.

Host defense in cutaneous leishmaniasis, due to Leishmania tropica, is largely--if not exclusively--cell mediated. We observed in vitro that draining lymph node lymphocytes from L. tropica-infected C57BL/6 mice activate L. tropica-infected macrophages to kill the intracellular parasites (leishmanicidal effect). Because direct cell contact between lymphocytes and infected macrophages is required to achieve a maximum leishmanicidal effect, this effect cannot be attributed solely to lymphokines. Furthermore, because effector lymphocytes induced no detectable damage to infected macrophages, the effect also differs from conventional lymphocyte-mediated cytotoxicity. The present study identifies the phenotype of the effector lymphocyte and assesses the genetic restriction of the lymphocyte-macrophage interaction. Nylon wool column-enriched T lymphocytes from infected mice activate macrophages for antileishmanial effects; treatment of lymphocytes with anti-Thy-1.2 antibody plus complement abolishes this capacity. Furthermore, treatment with anti-Lyt-1 antibody plus complement (but not with anti-Lyt-2 plus complement) likewise abolishes the effector capacity of the lymphocytes. Parallel studies reveal that the percentage of Lyt-1+2- cells present in draining lymph nodes increases during the course of infection and reaches a peak with the onset of spontaneous resolution of the infection. Syngeneic, but not allogeneic, combinations of lymphocytes and infected macrophages result in macrophage activation. Furthermore, treatment of cells with appropriate anti-Ia monoclonal antibody abrogates the antileishmanial effects. These results indicate that Lyt-1+2- lymphocytes obtained from mice with spontaneously healing L. tropica infections can exert antileishmanial effects in vitro. This effect is genetically restricted--most likely to the I region of the MHC--and requires direct cell contact. The temporal relationship between the appearance of these effector lymphocytes in mice and the onset of disease resolution argues that they may also exert these antileishmanial effects in vivo.

Functional roles of two polypeptide chains that compose an antigen-specific suppressor T cell factor.

The functional roles of the two polypeptide chains that compose the T cell suppressor factor (TsF) that mediates the antigen-specific and genetically restricted suppressor function were studied by using the heavy or light chains isolated from the conventional TsF or the 11S and 13S mRNA translation products of TsF. Either the heavy or the light chain of mRNA translation products reconstitutes the active TsF that suppresses the antibody response in an antigen-specific and genetically restricted manner when it is combined with the isolated heavy or light chain from the conventional TsF. As a consequence, the antigen-binding heavy chain mediates the antigen specificity of TsF. On the other hand, the I-J-positive light chain works as an element to determine the genetic restriction specificity. Thus, the identity of the histocompatibility between the I-J haplotypes on the light chain and the responding cell is essential for the functional expression of TsF. No genetic preference, however, was observed, in the association of the heavy and light chains of TsF.

A genetically restricted suppressor factor that requires interaction with two distinct targets.

We have previously described a genetically restricted suppressor factor (TsF3) that suppresses the terminal phases of the contact sensitivity response. The activity of TsF3 is restricted by genes in the H-2 (I-J) and Igh complexes. This report analyzes the mechanisms responsible for these genetic restrictions. One cellular target of TsF3 is an I-J-bearing antigen-presenting cell population that is sensitive to low doses of cyclophosphamide. To elicit suppression I-J homology is required between this antigen-presenting cell population and the TsF3 donor. In contrast, the Igh-linked genetic restriction exists between TsF3 and an unprimed cell population present in the recipient. These findings suggest that under these experimental conditions TsF3 acts by bridging the APC with cells of the host. Finally, we demonstrated that nonspecific bystander or cognate suppression can be mediated by TsF3, provided specific antigen is present in the site of the ongoing T cell response.

Long-term suppressor cell lines. II. Suppressor-target interactions.

Long-term nonhybridized murine suppressor T cell (Ts) lines, some of which have been in culture for over one year, are genetically restricted in their ability to suppress proliferation of primed lymph node cells (LNC). The genetic restriction maps to the I region of the major histocompatibility complex and resides in either the I-A, I-E or I-J locus. Suppressive activity is only slightly decreased following irradiation of the Ts with 2000 rds. The target for suppressive activity expressed by Ts cell lines is the helper T cell as suggested by experiments in which LNC proliferation was maximally suppressed when Ts were present early in the assay culture. The identity of the target cell was confirmed by experiments in which Ts were shown to suppress the anti-human gamma globulin plaque-forming cell response resulting from co-culture of primed B cells with cloned human gamma globulin-specific helper T cells.

Antigen recognition by a T cell clone outside the context of the major histocompatibility complex. A role for Mls in antigen presentation.

A T cell clone isolated from antigen-primed CB6/F1 mice was shown to proliferate to keyhole limpet hemocyanin (KLH) in the presence of irradiated syngeneic F1 spleen cells, as well as spleen cells from either parental strain (BALB/c and C57BL/6). The genetic restriction involved in this antigen-specific proliferation was mapped using BXD (C57BL/6 X DBA/2) recombinant inbred strains of mice to the Mls gene on chromosome one. To exclude the role of Ia antigens as the restricting determinants, monoclonal anti-Ia antibodies were used to block the in vitro proliferative response of this clone. Although anti-Iab and anti-Iad blocked the proliferation of this clone to KLH in the presence of irradiated spleen cells from either parent, this effect was shown to be dependent on Ia molecules passively absorbed by the T cell clone from the irradiated filler cells. Since the T clone expressed Thy-1.2 and Lyt-1+ differentiation markers, its helper activity was compared with other KLH carrier-specific clones in an in vitro antibody synthesis assay. The Mls-KLH-restricted T cell clone, in contrast to other carrier-specific, major histocompatibility complex (MHC)-restricted T cell clones, was unable to cooperate with trinitrophenyl (TNP)-primed B cells in the presence of TNP-KLH to generate an anti-TNP response. These experiments suggest that non-MHC determinants, such as autologous Mls gene products, may play a role in genetically restricted antigen recognition by T lymphocytes.

Genetic control of immune response to myoglobin. Ir gene function in genetic restriction between T and B lymphocytes.

We studied the genetic restrictions on the interaction between T cells, B cells, and antigen-presenting cells (APC) involved in the H-2-linked Ir gene control of the in vitro secondary antibody response to sperm whale myoglobin (Mb) in mice. The B cells in this study were specific for Mb itself, rather than for a hapten unrelated to the Ir gene control, as in many previous studies. Low responder mice immunized in vivo with Mb bound to an immunogenic carrier, fowl gamma globulin (F gamma G), produced B cells competent to secrete anti-Mb antibodies in vitro if they received F gamma G-specific T cell help. However, (high-responder X low responder) F1 T cells from Mb-immune mice did not help these primed low responder (H-2k or H-2b) B cells in vitro, even in the presence of various numbers of F1 APC that were demonstrated to be component to reconstitute the response of spleen cells depleted by APC. Similar results were obtained with B6 leads to B6D2F1 radiation bone marrow chimeras. Genotypic low responder (H-2b) T cells from these mice helped Mb-primed B6D2F1B cells plus APC, but did not help syngeneic chimeric H-2b B cells, even in the presence of F1 APC. In contrast, we could not detect any Ir restriction on APC function during these in vitro secondary responses. Moreover, in the preceding paper, we found that low responder mice neonatally tolerized to higher responder H-2 had competent Mb-specific helper T cells capable of helping high responder but not low responder B cells and APC. Therefore, although function Mb-specific T cells and B cells both exist in low responder mice, the Ir gene defect is a manifestation of the failure of syngeneic collaboration between these two cell types. This genetic restriction on the interaction between T cells and B cells is consistent with the additional new finding that Lyb-5-negative B cells are a major participant in ths vitro secondary response because it is this Lyb-5-negative subpopulation of B cells that have recently been shown to require genetically restricted help. The Ir gene defect behaves operationally as a failure of low responder B cells to receive help from any source of Mb-specific T cells either high responder, low responder, or F1. The possible additional role of T cell-APC interactions, either during primary immunization in vivo or in the secondary culture is discussed.

Self molecules in induction of hypersensitivity and tolerance in DNCB contact sensitivity in the guinea pig.

Dinitrophenylated macrophages are efficient inducers of contact sensitivity and of tolerance to dinitrochlorobenzene, depending on the mode of application. Contact sensitivity induced by an intradermal injection of DNP-M phi is genetically restricted, whereas tolerance induced by an intravenous injection is, in guinea pigs, not under control. This tolerance is complete in the majority of animals, but is reversed by DNCB in Freund's complete adjuvant and prevented by pretreatment with cyclophosphamide. Tolerance induced by an intravenous injection of the unconjugated hapten is not reversed by DNCB in FCA, but is abrogated by an intradermal injection of DNP-M phi. This abrogation does not occur, however, when DNCB in FCA is applied simultaneously with the DNP-M phi. In further experiments, it is demonstrated that the genetic restriction of induction of contact sensitivity by DNP-M phi is on the level of antigen recognition and is not due to the nonidentity of the Ia structures on macrohages used for induction and the Ia structures involved in elicitation of contact sensitivity.

Hapten-specific T suppressor factor recognizes both hapten and I-J region products on haptenized spleen cells.

The classical example of genetic restriction is associative recognition, the finding that cytotoxic T-cell killing requires matching between part of the major histocompatibility complex (MHC) of the stimulating cell and the target cell1,2. Its analysis would be facilitated by the study of a system in which antigen-specific T suppressor factor (TSF) was genetically restricted in its interaction with haptenized cells. However, only one such system is known3,4, although there are several systems in which the TSF must be syngeneic with other cells5–8. We now describe a genetically restricted TSF which arms an acceptor T cell. This acceptor cell shows some resemblance to the auxiliary T suppressor (Ts) cell, the acceptor T cell and the Ts3 described elsewhere5,6,9. In the presence of antigen (haptenized spleen cells) the armed acceptor cell releases a nonspecific inhibitor of the passive transfer of contact sensitivity (see. Fig. 1). The important finding is that the antigen will only trigger the release of the nonspecific inhibitor when there is matching in the I–J region between the TSF and the haptenized cell used as a source of the triggering antigen.

Genetic restriction in the induction of contact sensitivity by footpad cell transfer.

Cells taken from draining lymph nodes one day after application of oxazolone and picryl chloride induced contact sensitivity in syngeneic but not in allogeneic recipients. In contrast, the immunizing activity of cells taken four days after sensitization was not genetically restricted. The findings that '1-day' cells incubated with anti-hapten antibodies break down the genetic restriction, and that '4-day' cells lose their ability to induce contact sensitivity after complement treatment, suggest that two different mechanisms are involved in the induction of contact sensitivity.

Antigen- and receptor-driven regulatory mechanisms. VII. H-2-restricted anti-idiotypic suppressor factor from efferent suppressor T cells.

Azobenzenearsonate (ABA)-specific T cell-derived suppressor factor (TsF1) from A/J mice was used to induced second-order suppressor T cells (Ts2). Comparison of suppressor T cells induced by antigen (Ts1) with Ts2 induced by TsF1 revealed that Ts1 were afferent suppressors active only when given at the time of antigen priming, and not thereafter, whereas Ts2 could act when transferred at any time up to 1 d before antigen challenge for a delayed-type hypersensitivity response. This was true even when the recipient could be shown to be fully immune before transfer of Ts2, thus defining these cells as efferent suppressors. The anti-idiotypic specificity of the Ts2 was demonstrated by the ability of Ts to bind to idiotype (cross-reactive idiotype [CRI])-coated Petri dishes. A soluble extract from Ts2 (TsF2) was also capable of mediating efferent suppression that was functionally antigen- (ABA) specific. Comparison of TsF1 with this new factor, TsF2, revealed that both lack Ig-constant-region determinants, possess H-2-coded determinants, and show specific binding (to ABA and to CRI+-Ig, respectively). TsF1 acts in strains that differ with respect to H-2 and background genes, whereas TsF2 shows H-2- and non-H-2-linked genetic restrictions. This existence of H-2 restriction of TsF2 activity suggests that the apparent discrepancies in studies of H-2 restriction of TsF may be a result of the analysis of two separate classes of TsF, only one of which shows genetically restricted activity, thus unifying several models of suppressor cell activity.