In vivo effects of anti-Ia alloantisera. I. Elimination of specific suppression by in vivo administration of antisera specific for I-J controlled determinants

The specific regulation of immune responses by CD8+ T cells restricted by the MHC class Ib molecule, Qa-1

Over the last three decades considerable evidence has accumulated that CD8(+) T cells regulate peripheral immune responses, in part, by specifically controlling the outgrowth of antigen-triggered CD4(+) T cells. This regulatory function of CD8(+) T cells has been shown, in vivo, to control the emergence of autoreactive CD4(+) T cells as well as CD4(+) T cells reactive to conventional antigens, including alloantigens. In this review, we summarize the evidence that this immune suppression mediated by CD8(+) T cells is dependent, in part, on specific cognate interactions between MHC class I-restricted regulatory CD8(+) cells and antigen-activated CD4(+) T cells. Moreover, we review the evidence that regulatory CD8(+) T cells recognize antigen-activated CD4(+) T cells in a TCR specific manner restricted by the MHC class Ib molecule, Qa-1. The Qa-1 molecule may be uniquely qualified to serve this MHC restrictive function because, unlike conventional MHC molecules, it is preferentially and transiently expressed on activated and not resting CD4(+) T cells. This may assure that only recently antigen-activated CD4(+) T cells expressing Qa-1/TCR peptide complexes will induce regulatory CD8(+) T cells and subsequently become susceptible to regulation. Because Qa-1 also binds to self Qdm peptides that trigger NK (CD94/ NKG2) receptors on CD8(+) T cells, the machinery for homeostatic regulation of regulatory CD8(+) T cells can be envisioned. Finally, we propose a model by which these TCR specific, Qa-1-restricted regulatory CD8(+) T cells selectively downregulate antigen-activated T cells expressing TCRs of certain affinities. Ultimately these regulatory CD8(+) T cells control the peripheral TCR repertoire during the course of immune responses to both self and foreign antigens.

Murine immune response to Neisseria meningitidis group C capsular polysaccharide: analysis of monoclonal antibodies generated in response to a thymus-independent antigen and a thymus-dependent toxoid conjugate vaccine

Antibody (Ab) responses to polysaccharides (PSs) such as Neisseria meningitidis group C PS (MCPS) are characterized as being thymus independent (TI) and are restricted with regard to clonotype and isotype expression. PS conjugated to proteins, e.g., MCPS coupled to tetanus toxoid (MCPS-TT), elicits a thymus-dependent (TD) response. In order to understand the influence of the form of a vaccine (TI versus TD) on the Ab repertoire, we generated monoclonal antibody (MAb) panels from mice immunized and boosted with MCPS or MCPS-TT in different ways. The panels of MAbs were examined for isotype, fine specificity, affinity, and V(H) gene family usage. The use of MCPS-TT resulted in a shift in the isotype from immunoglobulin M (IgM) and IgG3 elicited in response to the MCPS to primarily IgG1. This isotype shift was accompanied by a change in the fine specificity of the response to the conjugate compared to that of PS. New fine specificities and increased affinity were observed in response to the TD antigen (Ag). Dot blot and Northern analyses of MCPS MAbs revealed that V(H) gene family usage is dominated by V(H)J558, used by 23 of 39 MAbs. V(H)3609 was seen in three MAbs of restricted fine specificity. V(H)Q52, V(H)7183, and V(H)VGAM3-8 were seen in more than one MAb across these panels, while V(H)10 and V(H)X24 were detected only once in response to the TI-2 Ag. All MAbs in the panels utilized kappa light chains, and all functional J(kappa) genes were expressed.

Murine immune responses to Neisseria meningitidis group C capsular polysaccharide and a thymus-dependent toxoid conjugate vaccine

The polysaccharide (PS) capsules of many pathogenic bacteria are poor immunogens in infants and young children as a result of the delayed response to PS antigens during ontogeny. The development of polysaccharide-protein conjugate vaccines for Haemophilus influenzae type b, which have proven to be efficacious in this age group, has led to active development by a number of investigators of conjugate vaccines for other diseases. We describe here the response of several mouse strains to the capsular PS of Neisseria meningitidis group C (MCPS) conjugated to tetanus toxoid (MCPS-TT) and the same response in BALB/c mice as a model of the immune consequences of conjugate vaccine immunization. The use of a conjugate vaccine results in a shift in the isotype elicited in response to the MCPS, from immunoglobulin M (IgM) and IgG3 to primarily IgG1. A response to MCPS-TT is seen even among mouse strains which respond poorly to MCPS itself, emphasizing the importance of a strain survey when choosing a mouse model for a vaccine. The marked increase in IgG1 antibody titer was accompanied by a large increase in bactericidal activity of sera from these animals. Animals primed with the conjugate vaccine demonstrated a booster response after secondary immunization with either the MCPS or the conjugate. The ability to produce a boosted IgG1 anti-MCPS response to the MCPS can be transferred to adoptive recipients by B cells alone from mice primed with MCPS-TT but not mice primed with MCPS alone. These data indicate that in BALB/c mice a single immunization with MCPS-TT is sufficient to induce a shift to IgG1 and generate a memory B-cell population that does not require T cells for boosting.

Immunohistochemical detection of tissue-infiltrating lymphocytes in mild urothelial dysplasia

The presence and distribution of immunocompetent cells in normal and dysplastic urothelium of the bladder were investigated in 3 patients. Using an indirect immunoperoxidase staining procedure, monoclonal antibodies reacting with B (Leu12+) and T (Leu4+) cells, cells of the suppressor/cytotoxic (Leu2a+), helper/inducer (Leu3a+) and natural killer (Leu7+) phenotypes, monocyte-macrophages (LeuM3+), and cells expressing interleukin-2 receptor and HLA-DR antigen (HLA-DR+) were tested in all specimens. The results confirmed the presence of a well ordered and compartmentalised distribution of immunocompetent cells in the normal mucosa far from dysplasia. There was an increased number of lymphocytes in the hyperplastic/dysplastic urothelium with associated Von Brunn's nests. Leu2a+ cells, HLA-DR expressing cells and monocyte-macrophages were present inside the epithelium, particularly within dysplasia and von Brunn's nests, but the Leu3a+/Leu2a+ ratio was not inverted (0.48 + 0.1 to 0.74 + 0.2). These findings reveal that in mild urothelial dysplasia with von Brunn's nests there is a spatial modification of the immunological barrier associated with the mucosa.

Suppressor T cells, antigen-presenting cells and the role of I-J restriction in oral tolerance to ovalbumin

Suppressor T cells (Ts) and antigen-presenting cell (APC) activity are both important for the induction of systemic tolerance after feeding protein antigens to mice. In this report, we have examined further the nature of the inter-relationship between Ts and APC in oral tolerance to ovalbumin (OVA). We found previously that oral tolerance to OVA could prevented by treating mice with oestradiol, and we now report that oestradiol enhances the ability of spleen APC to present OVA to T cells. In parallel, mice treated with oestradiol do not generate the Ts activity normally found after feeding OVA. Treatment of mice with anti-I-J antiserum prevents the induction of both tolerance and Ts activity after feeding OVA, but the suppressor effector cells generated by feeding OVA can not be depleted in vitro by treatment with anti-I-J antibody plus complement. In vivo administration of monoclonal anti-I-A antibody had no effect on oral tolerance to OVA. Our results show that induction of oral tolerance to OVA is an I-J-restricted phenomenon and we propose that this reflects an interaction between specific Ts cells and a population of I-J+ cells which we suggest are APC.

The role of antigen processing and suppressor T cells in immune responses to dietary proteins in mice

We have examined the role of Ts cels and APC in regulating the tolerance of systemic DTH in mice fed OVA. Oral tolerance to OVA was prevented by eliminating Ts with dGuo and by treating mice with anti-I-J antiserum. In addition, activating the reticuloendothelial system (RES) with oestradiol, muramyl dipeptide (MDP) or GvHR prevented the induction of tolerance. Further studies showed that prevention of oral tolerance correlated with the ability to enhance APC activity and that oestradiol also abrogated the induction of Ts after feeding OVA. Our results show that the tolerance of systemic DTH in mice fed OVA reflects complex interactions between APC and Ts and suggest that defects in these regulatory events may be responsible for clinical food sensitive enteropathy.

Presence of I-region gene products on the cells and their products of the dengue virus-induced suppressor pathway

We have studied both the cells and the suppressor factors of the dengue virus-induced suppressor pathway for the presence of I-region gene products. The suppressor activity of Ts1, Ts2 and Ts3 cells was abrogated by treatment with anti I-Jk or I-Ak anti-sera and complement. Both the suppressor factors were absorbed out by anti I-Jk and I-Ak immunosorbent columns. The activity of the suppressor factor was abolished by treatment with anti I-Jk antisera. Macrophage presentation of suppressor factor to precursors of Ts2 cells was abolished by treatment with anti I-Ak antisera and complement but not by anti I-Jk antisera. Thus I-region gene products were found throughout the dengue virus induced suppressor pathway.

Functional property of Ia-positive T cells in peripheral blood from patients with systemic lupus erythematosus

Ia-positive (Ia+) T cells in peripheral blood and their functional property were examined in patients with systemic lupus erythematosus (SLE). Binding of specific monoclonal antibodies was assessed by indirect immunofluorescence. Functional study of Ia+ T cells was carried out in coculture experiments by measuring the IgG secreted into the culture supernatant. We found that the percentage of Ia+ T cells in peripheral blood from patients with SLE was raised and the rise correlated positively with serum gamma globulin and IgG level. The elevation was further increased after stimulation with DNA in vitro, indicating the presence of DNA-sensitive T cells. Functionally, Ia+ T cells acted as helper cells in spontaneous IgG synthesis of SLE B cells, and were enriched in the OKT4 subset. These results indicate that SLE T cells are activated in vivo and that the Ia+ T cells may play a crucial role in the immunoregulatory function. Accordingly, demonstration of Ia antigens on T cells by monoclonal antibody may provide a useful tool for the measurement of immunological activity in patients with SLE.

A role for suppressor T cells in induction of self-tolerance

The potential role of suppressor T cells (Ts) in the induction of self-tolerance was investigated by eliminating I-J+ cells during ontogeny (I-J antigens are encoded by the I-J subregion of the murine major histocompatibility complex). To achieve this, F1 mice were exposed to anti-I-J antibodies via the transplacental route by mating B10.A(3R) females, preimmunized with B10.A(5R) cells, with CBA males. At 6 weeks of age, the offspring were injected with rat erythrocytes (RRBC) to induce erythrocyte autoantibodies. By comparison with age-matched controls, Ts-depleted mice produced significantly higher titers of autoantibody, whereas there was no difference in the antibody response of the two groups to the foreign determinants on the RRBC. The selective increase in autoantibody production was mirrored at the clonal level by the appearance of self-reactive B-cell hybridomas after fusion of RRBC-immune spleen cells with the NS-1 cell line. On the other hand, when helper cell function of RRBC-primed cells was measured in a T-cell proliferative assay, Ts depletion in utero resulted in enhanced T-cell activity to nonself (RRBC) but not to self (mouse erythrocyte) determinants. Thus, helper T cells recognizing nonself determinants on RRBC appeared to be responsible for activating self-specific B cells, presumably through linked recognition of different epitopes on mouse erythrocytes. Taken together, these findings indicate that elimination of I-J+ cells during ontogeny can lead to the appearance and activation of "forbidden" B-cell clones and points to a central role for Ts in induction as well as maintenance of self-tolerance.

I-J as a restriction element in the suppressor T cell system

This review attempts to sort out the differences between macrophage and T cell I-J determinants. We propose that suppressor T cells have receptors for self-I-J determinants which are expressed on macrophage-like accessory cells. The I-J determinants associated with accessory cells are responsible for the selection of the Ts receptors. Although the major histocompatibility complex is involved in the selection of Ts receptors, the receptors themselves need not be encoded by genes which reside within the MHC. In fact, the molecular genetic evidence presently available has established that suppressor T cell factors do not express gene products associated with the postulated I-J region of the H-2 complex. In spite of the failures of biochemists and molecular geneticists to identify I-J genes and gene products, there is extensive biological data demonstrating the existence of I-J. The activity of anti-I-J reagents has been verified by numerous laboratories. Sera containing anti-I-J activity have been prepared in many strain combinations. Immunization between a variety of strains differing at the purported I-J region produce active anti-I-J antibodies (Murphy et al. 1976, Tada et al. 1976, Pierres et al. 1977, Tada et al. 1978). Furthermore, in many suppressor cell systems the interactions of Ts cells and factors are restricted by I-J (Tada & Okumara 1980, Sorensen & Pierce 1982, Green et al. 1983, Dorf & Benacerraf 1984). Most investigators who have attempted to detect I-J have analyzed T cells. Since we propose that T cells express a complementary anti-I-J receptor, subsequent efforts at identifying I-J should include analysis of macrophage I-J determinants. In spite of extensive biological data, we still do not know if I-J is a protein, carbohydrate or lipid. In addition, the role of H-2 in determining I-J structure is unknown. Nevertheless, the overwhelming biological data demonstrate that I-J is an important structure for suppressor T cell interactions. Much remains to be accomplished, including the characterization of I-J products and locating the I-J genes.

T-cell responses induced by the parenteral injection of antigen-modified syngeneic cells. III. Dissociation of primed cytolytic T-cell and efferent suppressor-T-cell activity following intravenous injection of trinitrophenol-modified syngeneic spleen cells

The parenteral injection of ligand-coupled syngeneic spleen cells has profound effects on immune responsiveness. In this regard, it was examined whether the primed in vitro trinitrophenol (TNP)-specific cytotoxic T-lymphocyte (CTL) responses observed in splenic T-cell populations from mice injected intravenously (iv) with syngeneic TNP-modified spleen cells (TNP-SC) are related to the efferent-acting suppressor-T-cell (Ts) activity observed in splenocytes from iv primed mice. Treatment of mice with cyclophosphamide, adult thymectomy, or monoclonal anti-I-J antiserum prior to the iv injection of TNP-SC was found to eliminate the ability of splenic Ts from these mice to suppress the passive transfer of delayed-type hypersensitivity (DTH) mediated by trinitrochlorobenzene-immune T cells. In contrast, spleen cells from these pretreated mice showed no impairment in the development of augmented TNP-specific CTL responses upon in vitro restimulation with TNP-SC. Separation of the two activities was also achieved in a kinetic analysis. It is concluded that specific enhancement of CTL responsiveness induced by the iv injection of TNP-SC is related to the expansion of a population prelytic Lyt 2+ CTL effector cells which does not appear to contain efferent-acting Lyt 2+ Ts active in suppressing DTH expression.

Inactivation of specific anti-H-2 suppressor T cells by antisera to I-J and I-C subregion products of the H-2 complex

Two antisera to Ia antigens, products of the H-2 complex I-Cd and I-JkEk subregions, respectively, have been obtained by immunization of the F1 hybrids of recombinant strains of mice. These antisera are shown to display a 50% cytotoxic effect in vitro, in the presence of complement, upon lymphocyte populations immune to the H-2-complex antigens and enriched for specific suppressor T cells (SSTC) by fractionation on a monolayer of target cells. The specificity of anti-Ia cytotoxins is shown by cross-antibody absorption with T and B cells of mice originating from the recombinant H-2 haplotypes and bearing either particular I-Cd, I-Jk and I-Ek antigens, or their combinations. Anti-I-Cd cytotoxins were found to react with both B and T cells, but at a different rate, and the anti-I-JkEk serum contains two antibody types directed to I-Ek and I-Jk products, respectively, the latter being able to react preferently with T cells. Although both antisera do inactivate the in vitro SSTC function in the presence of complement to a similar degree, the inactivating action of the anti-I-Cd serum, but not that of the anti-I-JkEk serum, occurs without complement. SSTC are shown to bear both Ia-antigens, I-J and I-C, as shown by both inactivation of the anti-suppressor effect of the antisera absorbed with spleen cells of different H-2 origin, and variation of the H-2 origin of SSTC pretreated with the intact antisera. It is suggested that these two markers, located on the same SSTC, function differently in SSTC immune to the H-2 antigens, and I-C antigen expression on the SSTC surface is presumed to be required for their interaction with the inhibited responder T cells proliferating in MLC.

Characterization of rhesus macaque peripheral blood T-lymphocyte subpopulations

Highly enriched rhesus macaque (Macaca mulatta) peripheral blood T-lymphocytes were separated into functional subpopulations by Fc-receptors. The T-lymphocyte population was comprised of both Fc-IgM (T mu +, 3.4 +/- 1.6) and Fc-IgG (T gamma +, 16.2 +/- 4.0) bearing cells. T-cells depleted of cells bearing Fc-IgG receptors (T gamma -) and T gamma + subpopulations were characterized and assessed for functional activity. T gamma + and T gamma - subpopulations were found to have the following characteristics: 1) T gamma + cells were stimulated by concanavalin-A (Con-A)3, pokeweed mitogen (PWM), and phytohemagglutinin-P (PHA-P), while T gamma - cells were stimulated by Con-A and PWM, but not PHA-P; 2) T gamma - cells were found to mediate PWM induced differentiation of autologous B-cells including EAC+ and EAC- enriched subpopulations, while T gamma + cells did not induce differentiation; 3) T gamma + cells released soluble factors which depressed mitogen stimulation of T gamma- cells; and 4) approximately 8-10% of the T gamma + cells phagocytized IgG sensitized bovine red blood cell (BRBC) immune complexes.

Nonsteroid antiinflammatory drugs and tamoxifen for desmoid tumors and carcinoma of the stomach

The results of treatment of desmoid tumor patients with nonsteroid antiinflammatory drugs alone or in combination with tamoxifen are described. Tumor growth was inhibited in six of seven patients. Nonsteroid antiinflammatory drugs administered along with 5-fluorouracil and cyclophosphamide and other inhibitors of T-suppressor cells were used to treat nine patients with metastatic carcinoma of the stomach. Survival of these patients was extended so that after 12 months minimal follow-up the majority are well. A prospective controlled clinical trial is indicated.

H-2-determined kinetic differences for the induction of nucleoside-specific suppression

The kinetic and the H-2 requirements for the induction of nucleoside-specific suppression were examined in several strains of mice; specifically, whether adenosine (A)-coupled spleen cells given intravenously suppress the primary response to adenosine-KLH. The adenosine system was chosen because C57Bl/6 mice were originally found to be resistant to immune suppression when challenged 5 days after treatment with adenosine-coupled spleen cells. (Raps et al. J. Immunol. 126, 1542, 1981.) It was determined (i) whether A-specific nonresponsiveness is inducible in strains other than C57Bl/6; (ii) whether changes in hapten density on the A-conjugated spleen cells could alter C57Bl/6s ability to become nonresponsive, and (iii) whether there are interstrain differences in the time required to induce A-specific suppressor T cells (Ts). The results show that there are H-2-associated differences in the time required to induce A-specific immune suppression. While A-spleen cells failed to suppress the A-specific response in C67Bl/10 (H-2b), they did induce unresponsiveness in B10.D2 (H-2d on C57Bl/10 background). A 2.5-fold increase in epitope density of adenosine on cells did not influence the kinetics of suppression. C67Bl/6 were resistant to suppression on Day 5, but like the CB6F1, susceptible to unresponsiveness 10 days after treatment. Nonresponsiveness was T-cell-mediated and transferable across IgH-V barriers. Suppression induced by Balb/c donor mice is transferable to Igh-incompatible CAL-20 mice. These results are discussed in the context of genetic restrictions which regulate suppressor T-cell interactions.

Genetic control of PQ prolongation of the electrocardiogram in the mouse immunized with the killed group A streptococci

Genetic control of PQ prolongation of the electrocardiogram (ECG) in the mouse, immunized with killed group A streptococci, was studied by using various congenic mice. Mice of H-2a, H-2k and H-2f haplotypes showed high frequencies of PQ prolongation, while haplotypes of H-2b, H-2d and H-2s showed low frequencies of PQ prolongation. Studies using various recombinant mice revealed that at least one immune-associated (Ir) gene mapped in the left side of the I-B subregion. High responsiveness of F1 hybrids of H-2b and H-2d, as well as B10.A(5R) and B10.A(3R), suggests the existence of a complementing gene. In addition, the differences between C3H and CKB, as well as differences between C3H.SW and CWB, indicate that another Ir gene maps in the immunoglobulin heavy chain (Igh) coding loci. Repeated injections of anti-I-J or anti-I-A antisera also modified this PQ prolongation. These results suggested that both the major histocompatibility complex (MHC) and immunoglobulin (Igh) loci seem to be playing important roles in the pathogenesis of PQ prolongation.

Regulation of immune responses by I-J gene products. II. Presence of Both I-Jb and I-Jk suppressor factors in (nonsuppressor x nonsuppressor) F1 mice

Antigen-specific suppression to poly(Glu50-Tyr50) (GT) is under the control of two complementary immune suppressor (Is) genes located in the major histocompatibility (H-2) complex of the mouse. Suppressor strains of mice produce both suppressor T (Ts) cells and Ts-derived suppressor factors (TsF) that bear antigenic determinants of the I-J subregion of the H-2 complex. Nonsuppressor strains of mice, on the other hand, are not suppressed by GT preimmunization. These nonsuppressor mice, however, can be classified according to those that lack the ability to make GT-specific T cell-derived suppressor factor (GT-TsF) after GT injection (i.e., H-2a, I-Jk mice) and those that lack the ability to be suppressed by the appropriate GT-TsF (i.e., H-2b,g2, I-Jb mice). In the present study, we demonstrate that (H-2a x H-2b,g2)F1 hybrid mice produce distinct GT-specific suppressor factors of both parental I-J haplotypes. Moreover, only the I-Jb-bearing GT-TsF derived from these F1 hybrid mice is able to induce second-order suppressor cells (Ts2). This is consistent with the observation that injection of GT-TsF1 derived from C57BL/6 (I-Jb) mice into A/J (I-Jk) mice leads to the production of an antigen-specific I-Jk GT-TsF2. Our results suggest that Is gene complementation occurs through a different cellular mechanism that was previously observed for Ir gene complementation. Further, we show that complementing (non-suppressor X nonsuppressor)F1 hybrid mice produce an I-Jb (and not an I-Jk) GT-TsF1 and an I-Jk (not an I-Jb) GT-TsF2, thus suggesting a heterogeneity of Ia loci within the I-J subregion. Data presented in the present study suggest that there may be even more heterogeneity within the I-J subregion than has has been heretofore reported with regard to I-J expression on Ts.

Genetic control of allogeneic interactions in the guinea-pig. IV. The specific elimination of MLC suppressor cells by the in vivo administration of antisera against a GPLA-B region-controlled determinant

The in vivo effects of alloantisera, on the production of mixed leucocyte culture (MLC)-suppressor cells and suppressor factor (MLC-SF) as well as on the adoptive transfer of MLC suppression, were investigated. Intravenously administered anti-B.2 serum specifically eliminates B.2-associated MLC unresponsiveness and prevents the production of MLC-SF. By contrast, antisera directed against other B locus (homologous to the mouse H-2D or H-2K regions) or I region determinants do not appear to interfere with suppressor cell or factor production. Peritoneal exudate cells (PEC) from B.2-positive guinea-pigs can transfer MLC unresponsiveness to "normal' B.1-positive recipients; treatment of donor animals with anti-B.2 serum specifically prevents the transfer of MLC suppression. the results of this study support our earlier in vitro demonstration of B.2-bearing suppressor T cells which are sensitive to lysis by anti-B.2 sera in the presence of complement.

Genetic control of the immune response to haemoglobin. III. Variant A beta (bm12) but not Ae (D2.GD) Ia polypeptides alter immune responsiveness towards the alpha -subunit of human haemoglobin

Mice bearing the I-A subregion mutation bm12 were immunized and challenged with the alpha -subunit of human adult haemoglobin. Under conditions in which parental B6/Kh mice respond, B6.C-H-2bm12 mice are inhibited nearly 100% in their ability to respond to challenge to the alpha-chain of haemoglobin. D2.GD mice which express a variant Ae (E beta) polypeptide of the I-E subregion can respond as well as B10.D2 mice to both subunits (alpha- and beta-) of haemoglobin. These observations as well as other genetic mapping data confirm the I-A mapping of alpha -chain-specific Ir genes and extend the genetic fine mapping to the A beta gene within the I-A subregion or a combinatorial Ia determinant generated by an interaction of A alpha and A beta. In addition they implicate the Ia.8 specificity in determining immune responsiveness to alpha -chain determinants.

Regulation of immune responses by I-J gene products. I. Production and characterization of anti-I-J monoclonal antibodies

Using a novel, two-step functional screening procedure, we have isolated hybridoma B cell lines secreting monoclonal antibodies directed against gene products of the I-Jb and I-Jk subregions of the mouse H-2 complex. These monoclonal antibodies act in vitro by allowing nonresponder spleen cells to respond to normally suppressive quantities of poly(Glu50Tyr50) (GT) (WF8 series of anti-I-Jk monoclonal antibodies) or to suboptimal concentration of poly(Glu60Ala30Tyr10) (WF9 series of anti-I-Jb monoclonal antibodies). Some of the culture supernates that show augmenting activity bind GT-specific T cell-derived suppressor factor (GT-TsF), indicating that some monoclonal antiantibodies display a nonspecific enhancing effect, or, more likely, that anti-I-J monoclonal antibodies have been produced against I-J determinants not found on TsF. It is this last possibility that is most intriguing and that might serve as a means for exploring the heterogeneity of the I-J subregion. It is also possible that some of our monoclonal anti-I-J antibodies might detect antigenic determinants selectively expressed on suppressor T cells, helper T cells, and/or macrophages. In addition, we have demonstrated that monoclonal anti-I-J antibodies should be useful in the biochemical characterization and purification of a monoclonal GT-TsF. These haplotype-specific anti-I-J monoclonal antibodies should prove to be powerful tools for future studies exploring the role of I-J gene products in the regulation of specific immune responses.

Functional clonal deletion in immunological tolerance to major histocompatibility complex antigens

CBA (H-2k) mice were rendered tolerant to H-2d antigens by injection of (CBA X BALB/c)F1 spleen cells at birth. At intervals of 2 days to 12 weeks, the frequencies of anti-H-2d cytotoxic T lymphocyte precursor cells (CTL-P) in thymus and spleen were determined by using a limiting-dilution microculture assay system for CTL-P. This assay, utilizing irradiated H-2d stimulator cells and concanavalin A-induced spleen cell conditioned medium, was shown to be linear over the range 30 to 100,000 responder cells and uninfluenced by IJ-positive cells. A profound and long-lasting deficit in activatable CTL-P, first demonstrable by day 5 of life in the thymus and day 8-10 in the spleen, developed in mice rendered tolerant, reaching a greater than 95% reduction by 6 weeks. Functional clonal deletion thus seems to be at least as important in the tolerant state as suppressor T cells. Repeated in vivo administration of anti-IJk serum partially inhibited clonal deletion, suggesting either that suppressor T cells are actively involved in producing clonal deletion or that IJk-bearing cells in the donor inoculum or the host represent an important factor.

Effect of anti-Lyb3 antiserum on poly (L-glutamic acid, L-lysine)-induced B cell tolerance

The effect of anti-Lyb3 antiserum on antigen-specific B cell tolerance was investigated. The intraperitoneal injection of the nonimmunogenic copolymer L-glutamic acid60, L-lysine (GL) specifically reduces the ability of murine B cells to form GL-specific plaque-forming cell responses following challenge with the immunogenic conjugate of GL coupled to fowl gamma-globulin. It was found that this tolerance could be reversed or blocked by the intravenous injection of microliter quantities of anti-Lyb3 antiserum. However, this dose of antiserum neither reversed T cell tolerance induced with protein-coupled syngeneic erythrocytes nor induced tolerized B cells to secrete antibody. The results suggest that B lymphocytes can be rescued from GL-induced tolerance soon after induction and that Lyb3 determinants may play a functional role in the activation of antigen-specific B lymphocytes.

Characterization of renal tissue lymphocytes in patients with interstitial nephritis

Five patients with interstitial nephritis who presented with a variety of clinical profiles were studied with particular emphasis on documentation of the cellular types of potentially immunocompetent lymphocytes and mononuclear cells present within interstitial renal infiltrates. Immunohistologic studies coupled with conventional light and electron microscopic observations indicated that most mononuclear cells making up renal interstitial infiltrates were T cells. Some chronic inflammatory cell foci within renal interstitium were characterized by clusters of Ia antigen-positive T cells considered to be markers for activated lymphocytes. B cells were present in very small proportions (5 percent or less). The profile of immunocompetent cells present in lesions of interstitial nephritis suggests a major role for cell-mediated immunity in this disorder. Increase in tissue lymphocytes of the T gamma subclass with receptors for the Fc portion of immunoglobulin G (IgG) also suggests local activation of intrinsic suppressor cell mechanisms.

Distinct epitopes of Ik gene products identified by monoclonal antibodies

Analysis of reactivity of monoclonal anti-Iak alloantibodies, obtained by fusion between NS 1 myeloma and spleen cells from alloimmune A. TH mice, permitted the identification of 9 distinct determinants of the Ik gene products. Competitive binding experiments indicated that 2 private epitopes (defined by H8-109.13 and H8-138.4 antibodies) of the I-Ak product could be separated, thereby apparently splitting the Ia.2 specificity. A public determinant of the I-Ak molecule (identified by H8-15.9 antibody) was found expressed not only on the I-A products of the H-2b, H-2d, H-2ja, H-2p and H-2q murine haplotypes, but also on human HLA-DR antigens. Four determinants of the I-E/Ck antigen (defined by H7-8.26, H10-81.10, H10-93.2 and H8-86.2 antibodies) had a strain distribution analogues to the Ia.7 specificity. However, competitive binding experiments, and the cross-reactivity pattern with Ia-like antigens from other species (e.g. human HLA-DR antigens) indicated that these antibodies detected distinct determinants on the I-E/Ck molecule, thereby subdividing the broad Ia. 7 specificity. Two other determinants (defined by H9-14.8 and H9-15.4 antibodies) had a strain distribution that did not permit a precise assignment to a given Ia antigen, even though preliminary data suggested that they could detect separate determinants on the I-E/Ck product. All these monoclonal antibodies identified membrane antigens with the expected Ia tissue distribution pattern, and most of them could precipitate a molecule containing two chains of 28kD and 35kD, from mouse spleen cell lysates.

H-2-mediated resistance to an ecotropic type C retrovirus: localization of controlling genes and ontogenic studies of resistance

H-2 recombinant mice of the C57BL/10 series were used to study resistance to infection by an ecotropic (B-tropic) type C retrovirus. The gene(s) responsible for resistance was mapped to I-E/I-C subregions. Ontogenic studies indicated that this I-region mediated resistance is not present in the neonate but develops with age, and is firmly established within 2 weeks after birth. This temporary neonatal susceptibility in mice of resistant genotype is not the result of active suppression of the immune response.

T lymphocyte subpopulations and Ia-positive T cells in patients with immunodeficiency

T lymphocyte subpopulations (T gamma and Tmu) were studied in a group of 36 adult patients with immunodeficiency. Proportions and numbers of Ia(+) T cells were also studied in comparison to 46 normal adult controls. Values for per cent and total numbers of T gamma and Tmu cells indicated no uniform abnormality. Mean normal percentage of Ia(+) T cells was 2.4% whereas 16 to 29 immunodeficient patients showed elevated proportions and absolute numbers of Ia(+) T cells. Striking fluctuation in proportions of Ia(+) T cells was noted in serial studies of five immunodeficient subjects in contrast to similar analyses of normal controls. A correlation (P less than 0.01) was recorded between absolute numbers of Ia(+) T cells in immune deficiency patients and numbers of T mu cells. Depletion of T gamma cells by EA rosetting in patients with late-onset primary acquired hypogammaglobulinaemia did not result in significant change in IgG or IgM synthesis with T gamma-depleted T cells were co-cultured with normal B cells. Depletion of Ia(+) T cells likewise did not significantly influence Ig synthesis in co-culture with normal or immune-deficient B cells. These studies emphasize the complexity of defects present among any large group of patients with immune deficiency.

Studies of T- and B-cell interactions in adult patients with combined immunodeficiency

Cellular interactions involved in the pathogenesis of hypogammaglobulinemia were studied in six patients with common variable immunodeficiency. Amounts of immunoglobulin (Ig)G and IgM in the supernate of pokeweed mitogen-stimulated cocultures of normal and immunodeficient mononuclear cells were measured by radioimmunoassays. Mononuclear cells from three of six patients inhibited Ig production of normal B cells (P < 0.005). When purified patient and normal T cells were added to B cells in various autologous or allogeneic combinations, it was observed that immunodeficient T cells (AT) from four patients suppressed normal IgM synthesis. Allogeneic normal T cells did not provide help for B cells from these same immunodeficient patients. In two patients, autologous T cells were able to help autologous B-cell IgM synthesis in vitro. In five patients, AT cells inhibited normal B-cell IgG synthesis. Removal of T cells bearing Ia determinants or T cells with Fc-IgG receptors did not diminish the suppressive effect of AT cells on normal B-cell Ig synthesis. Addition of indomethacin, a prostaglandin synthetase inhibitor, did not abrogate the suppressive effect of immunodeficient mononuclear cells. Addition of hydrocortisone succinate (10 muM) did reverse the suppressive effect of AT cells on IgM production in one patient; however, no in vitro reversal of suppressor cell effect was recorded in five. Suppression by immune-deficient T cells was eliminated by 2,000 rad of x-ray irradiation in three patients. After x-ray irradiation immunedeficient T cells could function as helpers of normal B cells.

Immunosuppressive ALS. II. Antibody to Ia antigens in heterologous anti-lymphocyte serum

The relationship between Ia alloantigens and xenoantigens detected by immunosuppressive heterologous anti-lymphocyte sera has been investigated. Three rabbit anti-rat lymphocyte sera were examined for the presence of antibodies to Ia antigens. Two of these sera, an anti-thymus membrane and anti-lymphocyte sera detected labelled cell-surface Ia antigens (mol. wt 35,000 and 27,000) present on rat spleen B cells. The third antiserum, prepared against fractionated soluble lymphocyte antigens, was essentially non-reactive with these antigens. Of these three heterologous antisera, the anti-membrane serum reacted with the same antigens detected by two alloantisera. It seemed possible that such an antiserum could modify a recipient animal's immune response in vivo in a fashion identical to alloantibody to Ia antigens. In fact, all three heterologous antisera, including one devoid of antibody to Ia proved immunosuppressive in vivo. These results suggest that antibodies to antigens other than Ia can induce prolonged allograft survival. Since heterologous sera bind Ia antigens, it remains to be determined whether monospecific heterologous antisera to Ia antigens can allograft survival. The results raise the prospect that more than one antibody specificity may contribute to the immunosuppression achieved with ALS.

The involvement of suppressor T cells in Ir gene regulation of secondary antibody responses of primed (responder X nonresponder)F1 mice to macrophage-bound L-glutamic acid60-L-alanine30-L-tyrosine

(Responder [R] X nonresponder [NR])F1 mice give indistinguishable primary in vitro plaque-forming cell (PFC) responses to either R or NR parental macrophages (Mphi) pulsed with the Ir-gene controlled antigen L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT). However, such (R X NR)F1 mice, if primed to GAT, retained in vitro responsiveness to GAT-R-Mphi, but no longer responded to GAT-NR-Mphi. This suggested (a) a possible Mphi-related locus for Ir gene activity in this model, and (b) the occurrence of active suppression after priming with GAT leading to a selective loss of the usual primary responsiveness of (R X NR)F1 mice to GAT-NR-Mphi. This latter interpretation was tested in the current study. [Responder C57BL/6 (H-2b) X nonresponder DBA/1 (H-2q)]F1 mice were primed with 100 microgram GAT in pertussis adjuvant. 4-8 wk later, spleen cells from such mice were tested alone or mixed with normal unprimed F1 spleen cells for PFC responses to GAT-R-Mphi and GAT-NR-Mphi. The primed cells failed to respond to GAT-NR-Mphi, and moreover, actively suppressed the normal response of unprimed F1 cells to GAT-NR-Mphi. If the primed spleen cell donor had been treated with 5 mg/kg cyclophosphamide 3 days before priming or with 5-10 microliter/day of an antiserum to the I-Jb subregion [B10.A(5R) anti B10.A(3R)] during the first 4 days postpriming (both procedures known to inhibit suppressor T-cell activity), cells from such mice responded in secondary culture to both GAT-R-Mphi and also GAT-NR-MPhi. In addition, such spleen cells no longer were capable of suppressing normal F1 cells in response to GAT-NR-Mphi. Similar data were obtained using [CBA (H-2k) X DBA/1 (H-2q)]F1. Further, it was shown that (a) primary responsiveness to GAT-NR-Mphi was not an artifact of in vitro Mphi pulsing, because in vivo GAT-pulsed Mphi showed the same activity and (b) the secondary restriction for Mphi-antigen presentation was controlled by H-2 linked genes. These data suggest an important role for suppressor T cells in H-2 restricted secondary PFC responses, and also provide additional support for the hypothesis that Ir-gene controlled differences in Mphi antigen presentation are related to both suppressor cell generation and overall responsiveness in the GAT model.

Regulation of antibody heterogeneity by suppressor T cells: diminishing suppressor T cell activity increases the number of dinitrophenyl clones in mice immunized with dinitrophenyl-poly(Glu,Lys,Phe) or dinitrophenyl-poly(Glu,Lys,Ala)

The anti-hapten responses to the dinitrophenyl (Dnp) conjugate of the random linear terpolymers poly(L-Glu,LLys,LPhe), GLphi, or poly(LGlu,LLys,LAla), GLA, are of highly restricted heterogeneity. Thus, individual mice of most responder strains express an average of two to four anti-Dnp clones to Dnp-GLphi or Dnp-GLA, as measured by isoelectric focusing techniques. To explore whether suppressor T cells regulate the heterogeneity of the anti-hapten response to Dnp conjugates of these polypeptides, various procedures aimed at reducing suppressor T-cell activity were tested for their ability to alter the restricted isoelectric focusing spectrotypes. These procedures, such as adult thymectomy, administration of low doses of cyclophosphamide, and in vivo treatment with anti-I-J antisera, significantly increased the magnitude and heterogeneity of the anti-Dnp antibody response to Dnp-GLphi and Dnp-GLA in strains of mice that possessed responder Ir genes. Such methods failed to alter the nonresponder status of mice that lacked the appropriate Ir genes. Thus, in systems under Ir gene control suppressor T-cell mechanisms appear to be involved in the regulation of the heterogeneity of hapten-specific B-cell responses.