Immunosuppressive factors from lymphoid cells of nonresponder mice primed with L-glutamic acid60-L-alanine30-L-tyrosine10. IV. Lack of strain restrictions among allogeneic, nonresponder donors and recipients

Specific suppression of anti-DNA production in vitro

To investigate the regulation of anti-DNA antibody production, we generated anti-DNA-specific suppressor cells by exposing normal human T cells and a small percentage of adherent cells to high concentrations of DNA. These cells suppressed the production of anti-DNA by both autologous peripheral blood mononuclear cells (PBMC) and allogeneic PBMC derived from systemic lupus erythematosus (SLE) patients. Anti-DNA production was suppressed significantly more than anti-RNA, antitetanus, or total immunoglobulin production. Specific suppression was enhanced by increasing the numbers of DNA-primed CD8+ cells and was obliterated by irradiation of the DNA-primed cells. In contrast to T cells from normal individuals, T cells obtained from two intensively studied SLE patients were unable to generate specific suppressor cells for anti-DNA production in both autologous and allogeneic test systems. Despite this defect, these patients were still capable of generating specific suppressor cells for antibody production directed against an exogenous antigen, tetanus toxoid.

The effects of immunosuppressive pharmacological agents on the induction of cytotoxic and suppressor T lymphocytes in vitro

The immune system is regulated by the interactions among several distinct functional subsets of T cells. The action of several commonly used immunosuppressive drugs on the activation of cytotoxic T lymphocytes (CTL) and suppressor T lymphocytes (Ts) in the primary mixed lymphocyte reaction (MLR) was investigated. Cyclosporin A, hydrocortisone, and azathioprine were all found to inhibit both CTL and Ts activation when present at pharmacological doses in culture. When these drug-inhibited cultures were reconstituted with interleukin-2, however, clear differences between the effects of these drugs was observed. Cyclosporin A and hydrocortisone allowed the selective activation of Ts in the presence of interleukin-2, while azathioprine inhibition was not reversed by interleukin-2. Thus, CTL precursors appear to be directly inhibited by all of these drugs, but Ts precursors apparently are not inhibited by cyclosporin A or hydrocortisone provided interleukin-2 is present. These findings are discussed in terms of the activation requirements of CTL vs. Ts and the implications of the selective activation of alloantigen-specific Ts for prevention of allograft rejection.

Concomitant induction and persistence of hapten-specific suppressor and helper T cells in vivo

Intravenous injection of haptenized syngeneic lymphoid cells in the mouse induced a suppression in vivo against any immunogen carrying this hapten, introduced as a second antigen. Suppression was observed against any epitope on such a haptenized immunogen, thus largely excluding cross-reactions at the level of antigen-binding or idiotypy. However, when cells from such suppressed mice were assessed in vitro, it could be shown that significant T-helper activity had been induced by the same procedure, which in vivo resulted in suppression only. Thus, concomitant induction and persistence of hapten-specific suppressor and helper T cells is a result of the present immunization protocol. Both phenomena express the conventional requirements for physical linkage between hapten and immunogen to have an impact on the antibody response against the epitopes of the carrier. It is thus likely that the observed suppression/help in the present system does function at the level of handling the intact immunogen.

Antigen-specific suppressor T cell interactions. II. Characterization of two different types of suppressor T cell factors specific for L-glutamic acid50-L-tyrosine50 (GT) and L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT)

We have previously reported that two types of suppressor T cell factors (TsF) specific for L-glutamic acid50-L-tyrosine50 (GT) or L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT) can be distinguished based upon differences in their ability to suppress responses by allogeneic mice. Injection of GAT or GT induces a suppressor T cell subset that produces an antigen-binding, I-J+, genetically unrestricted, specific suppressor factor (TsF1). Injection of this factor plus small amounts of antigen induces a second-order suppressor T cell that produces an antigen-binding, I-J+, genetically restricted, specific suppressor factor (TsF2). In this report, we demonstrate that these two factors are also biochemically distinct. Monoclonal TsF1 molecules are composed of a single polypeptide chain that bears both the antigen-binding site and I-J determinant, whereas TsF2 molecules are composed of two disulfide-linked polypeptide chains, one of which is antigen-binding and I-J-, and the other, nonantigen-binding, I-J+. The antigen-binding chain must be added at culture initiation to achieve suppression, but the I-J+ chain can be added as late as day 3 with complete suppression observed. However, isolated chains from TsF2-producing hybridomas derived from three different haplotypes were unable to suppress immune responses when chains from heterologous TsF2 were mixed. Indirect evidence is presented that suggests that this restriction is because the chains fail to interact rather than the inability of the target cells to recognize both chains.

Antigen-specific suppression in genetic responder mice to L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT). Characterization of conventional and hybridoma-derived factors produced by suppressor T cells from mice injected as neonates with syngeneic GAT macrophages

Spleen cells from C57BL/10 mice injected with syngeneic B10 L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT)-pulsed macrophages (GAT-M phi) within 18 h of birth were unable to respond to soluble GAT, GAT-methylated bovine serum albumin, or B10 GAT-M phi as adults. Spleen cells from these neonatally treated mice responded at control levels to GAT presented in allogeneic M phi and to sheep erythrocytes. Partially purified T cells from these neonatally treated mice suppressed responses by syngeneic virgin, but not primed, spleen cells in an antigen-specific manner and acted during the early phases of the response. These responder GAT-specific suppressor T cells (GAT-TSR) were sensitive to anti-Thy-1 + C and 500-rad irradiation and have the phenotype Ly-1-2+, I-J+; GAT-TSR cells can only suppress responses by spleen cells syngeneic with the GAT-TSR cells at the I-J subregion of H-2. Restimulation of these Ts cells with syngeneic GAT-M phi induces an antigen-specific suppressor factor within the supernatant fluid. The factor, GAT-TsFR, is a glycoprotein with a molecular weight between 48,000 and 63,000, as determined by gel filtration chromatography using isotonic buffers; it bears serologically detectable determinants encoded by the I-J subregion of the H-2 complex, has an antigen-binding site for GAT and L-glutamic acid50-L-tyrosine50, and shares idiotypic determinants with anti-GAT antibodies. The presence of GAT-TsFR in the first 36 h of in vitro culture is required for significant suppression. Furthermore, only responses by spleen cell syngeneic with the cells producing GAT-TsFR at the I-J subregion are suppressed. The fusion of GAT-TsFR-producing cells with BW5147 resulted in generation of two hybridomas with properties and characteristics identical to those of the conventional GAT-TsFR with one exception: conventional and hybridoma 372.D6.5 GAT-TsFR only suppress responses by spleen cells of the I-Jb haplotype, whereas suppression mediated by the second hybridoma GAT-TsFR (372.B3.5) is genetically unrestricted. These hybridoma GAT-TsFR are compared with nonresponder GAT-Ts factor (GAT-TsF) and these responder and nonresponder GAT-TsF are considered in the context of suppressor pathways.

Mechanism responsible for the induction of I-J restriction on TS3 suppressor cells

The mechanisms responsible for the induction of I-J restrictions on third-order suppressor T cells (TS3) were analyzed. The I-J phenotype of the antigen-coupled cells used for priming restricted the specificity of the TS3 population. Thus, TS3 cells were only generated after priming with antigen-coupled I-J homologous cells. Identity at the I-JM (and I-E) subregions was sufficient for TS3 induction. Furthermore, priming of H-2 heterozygous mice with antigen-coupled parental cells generated TS3 that were restricted to the parental haplotype used for priming. The splenic cell population responsible for antigen presentation and induction of TS3 cells was fractionated. The cells involved in antigen presentation were found in the splenic adherent population and were absent in the fraction containing splenic nonadherent T and B cells. The subsequent activation and interaction of TS3 cells is also restricted by genes in the H-2 complex. The results are discussed in terms of a general mechanism responsible for the induction of restrictions in T helper and TS3 cells.

Cell-free translation of a biologically active, antigen-specific suppressor T cell factor

In vitro synthesis of an antigen-specific T cell suppressor factor (TsF) has been accomplished by using partially purified poly(A)-containing RNA in a rabbit reticulocyte lysate cell-free translation system. The poly(A)-containing mRNA was isolated from a cloned T cell hybridoma that constitutively produces a TsF specific for the synthetic polypeptide antigen poly-(LGlu60LAla30LTyr10) (GAT). The RNA was fractionated by size and translated in vitro. The 16S RNA fraction stimulated synthesis of a biologically active protein that specifically suppressed both the GAT-specific antibody response by spleen cells in vitro and the proliferation response to GAT by lymph node T cells from GAT-primed mice. Further, the suppressor factor had a binding site for GAT, a determinant encoded by the I subregion of the major histocompatibility complex (MHC), and an apparent Mr 19,000 estimated by functional assays on protein separated by NadodSO4/polyacrylamide gel electrophoresis. These results indicate that virtually no posttranslational modifications (other than proteolytic cleavage) are necessary to obtain biologically active TsF. Hence, the presence of carbohydrate or other chemical groups does not contribute to either the serological properties of GAT-TsF or its biological properties.

Purification and characterization of a monoclonal T-cell suppressor factor specific for poly(LGlu60LAla30LTyr10)

A monoclonal T-cell-derived suppressor factor specific for the terpolymer poly(LGlu60LAla30LTyr10) produced by the T-cell hybridoma 258 C4.4, was purified to homogeneity. This was accomplished by fractionation of the culture medium by using a combination of affinity chromatography and reverse-phase and ion-exchange high-performance liquid chromatography. The purified factor is composed of a single Mr 24,000 polypeptide chain, and the homogeneous protein maintains the ability to suppress antibody and T-cell proliferative responses to poly(LGlu60LAla30LTyr10) specifically. The specific activity of pure suppressor factor is calculated to be 8 X 10(7) units/micrograms.

Monoclonal antibodies as a tool for phylogenetic studies of major histocompatibility antigens and beta 2-microglobulin

The cross-reactivity of several monoclonal antibodies recognizing monomorphic determinants of human HLA-A, B, C, and DR antigens and human beta 2-microglobulin (beta 2m) has been studied on peripheral blood leukocytes in 24 different species. An monoclonal HLA-A-, B-, and C-specific antibody and four monoclonal HLA-DR-specific antibodies cross-reacted with cells from all the primate species tested. Furthermore, antibodies HLA-DR-specific were positive with peripheral blood leukocytes (PBL) from cows, goats, sheep, horses, and dogs. Two monoclonal beta 2m-specific antibodies, which were positive with PBL from certain primates, also reacted with cells from cows, goats, sheep, horses, and dogs. Two other beta 2-m-specific antibodies reacted only with PBL from chimpanzees. No reaction could be detected with all our reagents in other classes tested (birds, reptiles, amphibians, and Teleostei).

Role of macrophages in the transmission of dengue virus-induced suppressor signal to a subpopulation of T lymphocytes

In dengue type 2 virus (DV)-infected mice, the virus-specific immunosuppression is mediated by a two-step mechanism: (1) induction of T suppressor cells (Ts1) by by virus to produce a suppressor factor (SF) which (2) stimulates another subpopulation of T cells (Ts2) to produce prostaglandin which finally mediates suppression. SF suppresses DV-specific IgM plaque-forming cells (PFC) in the spleen cells sensitized in vivo or in vitro, as detected by Jerne's haemolytic plaque technique. The present study enabled us to investigate the role of an intermediary cell in transmission of the suppressor signal from Ts1 to Ts2. It was observed that SF was adsorbed on the surface of peritoneal macrophages. Live macrophages adsorbed SF, retrieved it from that adsorbed on heat-killed macrophages and presented it to the target cells. Heat-killed macrophages adsorbed SF to the same extent as live ones, but could present it to the target cells by themselves. The target cells of SF were unprimed splenic T lymphocytes. SF suppressed DV-specific PFC in syngeneic spleen cells and was adsorbed on syngeneic macrophages, but not on those from allogenic animals. The findings described here show that the presence of live macrophages is obligatory for transmission of the suppressor signal to the target Ts2.

Haplotype-specific suppression of antibody responses in vitro. II. Suppressor factor produced by T cells and T cell hybridomas from mice treated as neonates with semiallogeneic spleen cells

Culture supernatant fluids from spleen cells from C57BL/10 or BALB/c mice neonatally treated with semiallogeneic (B 10.D2 x B10)F1 cells to induce haplotype-specific suppressor T cells and restimulated with macrophages syngeneic at I-A with the allogeneic haplotype encountered as neonates contain a soluble factor capable of suppressing primary in vitro antibody responses of normal syngeneic spleen cells in a non-antigen-specific manner. This haplotype-specific suppressor factor, TsF-H, has also been recovered in culture fluids of a T cell hybridoma produced by fusion of the AKR thymoma BW5147 and the haplotype-specific suppressor T cells. TsF-H is inactivated by low pH (3.5) trypsin, for 30 min at 50 degrees C, and has a molecular weight in the range of 45,000 to 68,000. Studies with specific immunoabsorbents demonstrate the presence of determinants encoded by the I-A subregion of the haplotype of the T cell producing TsF-H but not I-J subregion or immunoglobulin constant-region determinants on the TsF-H. Suppression is restricted to primary in vitro antibody responses, and not secondary antibody, mixed lymphocyte, or cytotoxic lymphocyte responses by spleen cells syngeneic at the I-A subregion of H-2 with the T cell producing the factor. The properties and activities of TsF-H and the haplotype-specific suppressor T cell are compared and contrasted with antigen-specific and genetically restricted suppressor T cells and their factors.

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.

Genetic analysis of immune suppression. I. Gene complementation is required for suppression of antigen-specific proliferative responses by T-cell derived factors

We have analyzed the genetic control of susceptibility to suppression by 1-J+ , suppressor-T-cell derived factors (TsF) specific for the synthetic polymer L-glutamic acid50-L-tyrosine50 (GT). GT-TsF activity was measured as specific inhibition of proliferative responses to GT developed in cultures of lymph-node T cells from mice primed with GT complexed to methylated bovine serum albumin (GT-MBSA). These experiments demonstrated that there is no MHC-encoded genetic restriction between donors and recipients of GT-TsF in suppression of proliferative responses. We have also confirmed the observations that mice of the H-2b, H-2d, and H-2k haplotypes can produce GT-TsF, whereas H-2a mice do not, and that H-2a, H-2d, and H-2k mice are sensitive to GT-TsF from all producer strains, whereas H-2b mice are not sensitive to GT-TsF from any strain. Analysis of the effect of GT-TsF on responses by mice bearing recombinant haplotypes suggests that at least two genes are required for susceptibility to GT-TsF and that these genes show coupled complementation.

Antigen-specific T-cell factors

Antigen-specific T-cell factors are mediator molecules which are produced by helper and suppressor T cells and which can perform the function of those cells in an antigen-specific manner. They probably play an important part in immunoregulation. The major histocompatibility complex has a controlling influence on their structure and activity, while their antigen-recognition properties may be conferred by immunoglobulin V regions. Interest in the factors derives from three related areas of research, namely (i) the problem of T-cell recognition of antigen; (ii) the mechanisms of cellular interactions in antibody production and cell-mediated immunity; and (iii) the genetic control of immune responses. This review discusses the literature up to June 1980 on their production, structure, genetic restriction and mechanism of action.

Suppression of antibody and T cell proliferative responses to L-glutamic acid60-L-alanine30-L-tyrosine10 by a specific monoclonal T cell factor

The synthetic terpolymer L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT) stimulates GAT-specific suppressor T cells in nonresponder mice. Extracts from these T cells contain a GAT-specific soluble T cell suppressor factor (GAT-TsF) that inhibits development of GAT-specific plaque-forming cell (PFC) responses by spleen cells from nonresponder mice stimulated with GAT complexed to methylated bovine serum albumin (GAT-MBSA). These extracts also contain a factor that inhibits development of GAT-specific proliferative responses by GAT-MBSA-primed, nonresponder lymph node T cells. Experiments reported in this manuscript show that a hybrid T cell line, produced by fusion of the AKR thymoma, BW5147, with spleen cells that contain GAT-specific suppressor T cells, produces a constitutive GAT-specific suppresor factor that functionally and serologically resembles GAT-TsF extracted from T cells. More importantly, both GAT-specific PFC and T cell proliferative responses are inhibited by this factor.

Antigen specific T cell factors

Antigen specific helper and suppressor factors have a similar structure, with two major sections, a 'variable region', determining antigen specificity which is likely to be controlled by Immunoglobulin VH genes, with which it shares idiotype and framework determinants. Specific factors also have a 'constant region' which does not vary between strains and minimally between species or with the antigenic specificity of the factors, which are defined by rabbit anti-helper or anti-suppressor antisera. This region determines the biological function of the molecule. Anti-Ia antisera react with factors, but the nature and function of Ia molecules on T cell factors is still unclear. The model of specific factor structure, with C and V regions resembles that of immunoglobulin, and it is thus possible that the C region of factors, like the V region is Ig linked. Because there are multiple T cells, helping and suppressing antibody responses specifically, it seems improbable that all of these cells could interact directly with rare antigen-specific B cells. Thus we propose that macrophage presenting cells are the key to the integration of signals for immune induction and regulation for T and B cells. Since Ir genes have been identified in the macrophage presenting cells interacting with both T and B cells, this suggests that macrophage Ia antigens are of importance in the integration of triggering signals for the lymphoid pool.

Major histocompatibility gene complex (MHC)-coded determinants on antigen-specific suppressor factor for delayed-type hypersensitivity and surface phenotypes of cells producing the factor

Antigen-specific suppressor factor for delayed-type hypersensitivity (DTH) to sheep red blood cells (SRBC) was obtained by incubating in vitro spleen cells from CBA mice (H-2k) injected intravenously 3 days previously with 1 x 10(9) SRBC. The suppressor factor was characterized for major histocompatibility gene complex (MHC)-coded antigenic determinants by passing the factor through immunosorbents coupled with appropriate alloantisera. The suppressor factor was absorbed by anti-H-2k, anti-Iak and anti-I-Jk immunosorbents but was not retained by anti-Ias, anti-I-Js, anti-I-Ak, anti-I-E/Ck or anti-H-2Kk immunosorbents. In addition, the factor bound to an immunosorbent coupled with rabbit antibodies against carbohydrate-defined Ia antigens. Furthermore, the suppressive activity that was absorbed was quantitatively recovered in the acid eluates from the immunosorbents. Treatment of the spleen cells with anti-Lyt-1.1 antiserum and complement completely abrogated their ability to elaborate the suppressor factor in vitro. In contrast, treatment with anti-Lyt-2.1 or anti-Iak antiserum and complement had no effect. Thus, it appears that the suppressor factor for DTH to SRBC bears I-J subregion-coded determinants, and its production is dependent on cells which have the Lyt-1+,2- and Ia- phenotype.

Cellular consequences in the suppression of antibody response by the antigen-specific T-cell factor

Cellular events mediated by antigen-specific soluble factor extracted from carrier-primed suppressor T cells (TsF) in the suppressive interaction was studied. Keyhole limpet hemocyanin (KLH)-specific TsF directly acts on KLH-primed, I-J positive, nylon-wool-adherent T cells that have an acceptor site for TsF. The nylon-wool-adherent T cells, after accepting TsF in the presence of specific antigen, generate new suppressor T cells acting as an actual effector cell type. Antigen-specificity and syngeneity at I-J between TsF and acceptor T cells are both required for the induction of new suppressor T cells. Newly induced suppressor T cells, however, suppress both syngeneic and allogeneic responses in an antigen-nonspecific fashion.

Comparison of antigen-specific I-region-associated cell interaction factors

Two basic types of factors reacting with anti-I region (anti-Ia) antisera are compared, those derived from macrophage-like antigen presenting cells and others derived from T-lymphocytes, of either the suppressor or helper type. Despite the common property of reacting with anti-Ia antisera, the two sets of factors differ by many criteria. Macrophages, upon culture with antigen, release complexes of Ia antigen and a fragment of the original immunogen. This material is only produced by responder macrophages and thus appears to be a soluble Ir gene product. The genetic restriction of the T-macrophage interaction was investigated in chimeras, and it was found that the host environment as well as the donor genotype was of importance in determining restrictions, which were thus not really directed to "self." There was no evidence for intrinsic T-cell Ir genes, as nonresponder stem cells developed into responder T-cells in a (responder X nonresponder) F1 environment. However, these cells only responded in the presence of responder macrophages. Specific T-cell factors are different in nature. These all react with anti-Ia antisera, but the nature or function of the T-cell Ia is unknown. The basic structure involves a VARIAble region" responsible for antigen binding which, as it reacts with anti-idiotype antisera and anti-variable region framework antisera is an immunoglobulin variable region. There is also a "constant region," defined by its biological properties as well as by specific rabbit antisera. This two-region nature of specific factors is reminiscent of immunoglobulin structure and it is a reasonable hypothesis that the constant region is linked to the Ig cluster of genes.

Shared idiotypic determinants on antibodies and T-cell-derived suppressor factor specific for the random terpolymer L-glutamic acid60-L-alanine30-L-tyrosine10

T-cell derived suppressor factors (TsF) specific for the random copolymers L-glutamic acid60-L-alanine30-Ltyrosine10 and L-glutamic acid60-L-alanine40, referred to as GAT and GA, respectively, were prepared and partially purified on the approprate antigen immunoadsorbents. GAT-TsF obtained from nonresponder DBA/1 (H-2q) and SJL (H-2s) mice were passed over immunoadsorbents prepared from normal guinea pig serum (NGPS) or guinea pig anti-idiotype antiserum (anti-CGAT) specific for a common cross-reactive idiotype found on most anti-GAT antibodies in all mouse strains tested. Both the directly suppressive activity of the GAT-TsF and the ability of GAT-TsF to induce new suppressor T cells (Ts2) in vitro were adsorbed to and fully recoverable from the guinea pig anti-CGAT-Sepharose immunoadsorbent, while the TsF passed through the control NGPS-Sepharose without appreciable binding. The SJL GAT-TsF specifically eluted from anti-CGAT-immunoadsrobents was shown to still posses I-J determinants. These data provide evidence suggesting a sharing of V region structures between B-cell antibody and T-cell suppressor factor specific for an antigen (GAT) under Ir gene control, in agreement with earlier studies on T and B-cell alloreceptors, T-cell helper factors, and T and B-cell receptors for conventional antigens.