Different functional specificity repertoires for suppressor and helper T cells

Regulatory mechanisms in immune responses to heterologous insulins. II. Suppressor T cell activation associated with nonresponsiveness in H-2b mice

Murine antibody responses to insulins are controlled by MHC-linked Ir genes. Although mice of the H-2b haplotype do not make antibody in response to pork insulin, we demonstrate in this communication that immunization with pork insulin stimulates radioresistant, Lyt-1+2- helper T cells that are capable of stimulating secondary antibody responses to pork insulin in vitro, but that this activity is masked by radiosensitive, Lyt-1-2+, I-J+ suppressor T cells. The suppressor T cells, present after immunization with pork insulin but not beef insulin, suppress the secondary response to pork but not beef insulin. The amino acid sequences of pork and beef insulins differ only at the A-chain loop; thus, pork insulin-specific suppressor T cells appear to recognize the A-chain loop determinant of pork insulin. The amino acid sequences of mouse and pork insulin are identical in the A-chain loop, which suggests that these suppressor T cells may be self-reactive. If this interpretation is correct, these suppressor T cells could be involved in the maintenance of self-tolerance to insulin. Nevertheless, these data clearly demonstrate that genetically determined nonresponsiveness in H-2b mice is conferred by activation of dominant, insulin-specific suppressor T cells (Ts), rather than by a defect in the stimulation of insulin-specific helper T cells (Th).

Immunoregulation of lysozyme-specific suppression. I. Induction and suppression of delayed-type hypersensitivity to hen egg-white lysozyme

Subcutaneous immunization with hen egg-white lysozyme (HEL) in complete Freund's adjuvant induces, both in antibody responder and nonresponder mice, a classical delayed-type hypersensitivity (DTH) reaction evaluated as footpad swelling. This response can be specifically transferred to naive recipients by Lyt-1+2- T cells and passive transfer is restricted by genes mapping in or to the left of the I-A region of the H-2 complex. Fine antigenic specificity analysis shows that HEL-primed T cells mediating DTH recognize ring-necked pheasant egg-white lysozyme, a lysozyme closely related to HEL, but fail to respond to human lysozyme, differing from HEL at 40% amino acid residues. Complete cross-reactivity between native and denaturated (reduced and carboxymethylated) HEL is exhibited by T cells involved in the DTH response. Subcutaneous injection of HEL coupled to spleen cells is also able to induce antigen-specific and genetically restricted DTH responses whereas the same cells administered by i.v. or i.p. route induce predominantly suppressor T cell activation. These suppressor T cells specifically inhibit the induction phase of DTH reactivity to HEL.

Suppression of type II collagen-induced arthritis by the intravenous administration of type II collagen or its constituent peptide alpha 1 (II) CB10

Intravenous administration of Type II collagen to rats prior to immunization with Type II collagen suppresses hind paw inflammation, humoral response to Type II collagen, and the severity of the arthritic lesion. Suppression of inflammation and its severity as well as the humoral response can also be induced by the prior intravenous administration of alpha 1 (II) CB10 a cyanogen bromide peptide derived from Type II collagen. Suppression of arthritis is disease specific; intravenous administration of either Type II collagen or alpha 1 (II) CB10 does not have an effect on adjuvant-induced arthritis. These studies indicate that structural determinants of alpha 1 (II) CB10 (Mr 30,000), a peptide located near the carboxy terminus of the collagen molecule, can induce suppression and suggest that these determinants may be responsible for the suppression of arthritis when Type II collagen is administered intravenously.

An appraisal of survival strategies

Only a few years ago parasite immunology looked an unattractive subject better left to the dogged specialists. Parasites and hosts had been playing chess together for a million years, and there seemed little prospect of perturbing matters in favour of the host immune system. All that has changed, for three reasons. Firstly, we have learned how to grow at least some parasites in vitro, and prospects of doing so with others are encouraging. Secondly, progress in cellular immunology has revealed the sort of loopholes in the host defence system which parasites are likely to exploit: we are learning the questions which matter about parasites as antigens. Thirdly, and most importantly, molecular genetics is being brought to bear on parasites: we can now see a real, though long-term, prospect of manufacturing practicable vaccines through bio-engineering, and more immediately it gives us the tools needed to probe the host immune responses in the form of cloned antigens.

Regulatory mechanisms of the immune response to heterologous insulins. I. Development and regulation of plaque-forming cell responses in vitro

We, as well as many other investigators, have been studying the regulation of immune responses to insulin as a model system of H-2 linked immune response (Ir) gene control. Although antibody responses by mice to heterologous insulins are qualitatively controlled, antibodies that are generated to one species of heterologous insulin cross react extensively with other species. The exquisite control of responsiveness is regulated by T cells that appear to recognize differences in the amino acid sequences of the A-chain loop of insulin. Our previous studies of the mechanism(s) by which Ir genes regulate T cell activity to insulin have been confined to an adoptive transfer model because traditional cell culture techniques using normal or insulin-primed spleen cells have failed to generate insulin-specific plaque-forming cell responses in vitro. In this communication we demonstrate that more vigorous immunization protocols and the use of lymph node T cells as a source of helper T cells can circumvent this problem. More importantly, all of the major features of the regulation of responses to insulin that have been observed in vivo are reflected in this in vitro system. Thus, these experiments provide the essential foundation for future dissection of the mechanism of Ir gene control of responses to insulin.

Immune recognition of insulin by H-2b mice: the mutation in the I-Ab beta gene of the B6.C-H-2bm12 mouse alters the self-I-A-restricted T cell repertoire

The response to heterologous insulin in H-2b mice is restricted to the A chain loop determinant(s) of beef insulin. The recognition of this specificity requires the expression of the immune response (Ir) gene epitope Ia.W39 which is absent from the I-Ab mutant B6.C-H-2bm12 (bm12) mice. This restriction could reflect the inability of H-2b antigen-presenting cells (APC) to present other insulin determinants or may reflect "self-major histocompatibility complex"-dependent influences on the generation of the T cell repertoire. To assess these possibilities we analyzed the genetic control and fine specificity of the insulin-specific T cell repertoire of H-2b mice by fusing the AKR thymoma BW5147 with T cells of C57BL/6 mice which had been immunized in vivo and challenged in vitro with beef insulin. The cloned hybridomas that we have produced respond to APC either alone or in conjunction with insulin by the production of interleukin 2. The insulin-specific hybridomas vary in their fine specificity such that some clones recognize a determinant(s) shared by beef, sheep and pork insulin and the isolated B chain, while other clones recognize a determinant(s) shared by beef and sheep insulin only, likely to involve amino acids 8 and/or 10 of the A chain loop. The presentation of insulin to these hybridomas is restricted by I-Ab, but not by Ia.W39. This analysis revealed that the insulin-specific immune potential in H-2b mice is of greater scope than previously defined and led us to consider, whether insulin nonresponder bm12 mice also possess a latent insulin-specific immune potential. Our study of the insulin-specific immune recognition by bm12 mice shows that these nonresponders do possess insulin-specific T cell clones. Despite the fact that the I-Ab and I-Abm12 gene products differ only by 3 amino acids, insulin-specific C57BL/6 and bm12 hybridomas are restricted to recognize exogenous antigen only in the context of C57BL/6 and bm12 APC, respectively. Furthermore, upon direct analysis of autoreactive subclones, a similar although not complete, restriction was observed. The implications of these findings for understanding the mechanism of Ir gene control are discussed.

Differential induction of help and suppression in mice by bifunctional antigens administered via different routes

Bifunctional antigens composed of one L-tyrosine-p-azobenzenearsonate (Tyr-ABA) carrier epitope and one dinitrophenyl (DNP) haptenic epitope separated by 6-aminocaproyl or polyprolyl spacers induced weak IgM anti-DNP plaque-forming cell (PFC) responses in the spleens of mice immunized intraperitoneally, without detectable IgG PFC. However, the same antigens introduced into the footpads induced IgG PFC responses in the draining lymph nodes which rose to levels greater than 100/10(6) viable lymphocytes. Moreover, the response in the lymph nodes to booster injections of antigen was characteristic of secondary T-dependent antibody responses, whereas the splenic secondary response simply mirrored the primary. The magnitude of the IgG PFC response was influenced by the size of the spacer and by the strain of mice, although genetic control did not map to the major histocompatibility complex. Prior i.p. immunization suppressed the IgG response to subsequent immunization in the footpads. This suppression could be transferred to normal syngeneic recipient mice with spleen cells from suppressed donors. Suppressor activity was eliminated by treating the spleen cells with anti-Thy-1 antibody prior to transfer, establishing the T-cell dependency of suppression. Suppression was also induced by Tyr-ABA itself, but not by DNP-lysine, indicating the epitope specificity of the suppressor cells. Thus, bifunctional antigens induce dominant suppression in the spleen but significant help in lymph nodes.

Determinants of ryegrass pollen cytochrome c recognized by human IgE and murine monoclonal antibodies

In attempts to produce fragments of an allergenic molecule which would retain allergenic and/or antigenic determinant(s), the cytochrome c of ryegrass (RG) pollen, which had been shown to be an allergenic constituent of this pollen, was digested with trypsin and chymotrypsin and the resulting fragments were separated by high performance liquid chromatography. Several of these fragments were shown, with the aid of the radioallergosorbent test and solid phase radioimmunoassays, to bind IgE antibodies present in a pool of six sera from grass-sensitive patients and three murine monoclonal antibodies, designated as Mab 41, Mab 42 and Mab 43, which had been originally produced against the crossreacting cytochrome c of Kentucky bluegrass (KBG). In summary, (i) fragments C-67 and C-74 reacted with all antibodies, (ii) fragments T-45, T-46 and C-69 bound to human IgE antibodies as well as to Mab 41 and Mab 42, but not to Mab 43, (iii) fragment T-44 reacted only with Mab 41 and Mab 42, and (iv) fragment C-83 bound only Mab 42 and Mab 43. On the basis of these results, it is concluded that (i) immunochemically active fragments of the RG cytochrome c can be readily produced by enzymatic degradation, (ii) there is significant crossreaction between the antigenic determinants of RG and KBG cytochromes c, (iii) whereas all fragments possessed at least two of the original antigenic determinants, fragments C-83 and T-44 were devoid of allergenic determinants, (iv) the antigenic determinants recognized by Mab 41 and Mab 42 were different from those reacting with human IgE antibodies and Mab 43, (v) each of the three monoclonal antibodies recognized a distinct antigenic determinant, (vi) fragments C-67 and C-74 possessed all determinants recognized by the human IgE and mouse antibodies used.

Contrasuppression: the second law of thymodynamics, revisited

The data discussed here touch upon several issues in the evolving story of T cell contrasuppression, the underlying theme being that of heterogeneity. First, there is the issue of function. We are considering here only those cells that affect the function of secretory differentiation. We have evidence that different contrasuppressor cells exist for clone growth, but have not yet studied them in the same depth as those for secretory differentiation. Second, there is the important issue of target cells. In this article by Green and Gershon it is pointed out that there is clear evidence that contrasuppressor effects can work by protecting helper cells from suppressor cell effects in vitro. On the other hand, direct additional inhibition of the suppressor cells themselves has not been excluded. The latter point is also true in our system. However, we must suppose for the sake of simplicity in many of our experiments that if suppressors are not the target of the contrasuppressor effects then the B cells themselves probably are. This is because the tumor cells engage in a spontaneous rate of growth and differentiation in the absence of help or suppression. When T cell-dependent, specifically triggered effects reduce this spontaneous behavior, then a suppressive effect must have been delivered directly to the B cells. This is a simplifying assumption which is attractive, but since the experiments are carried out in vivo and thus may be affected by some factors that we have not yet recognized, we are not confident on its "intuitive" appeal. A third issue revolves around triggering specificity. One of our contrasuppressors exhibits the phenomenon of carrier crossreactivity (CRCS) and is thus behaving in accord with expectations aroused by Green and Gershon in this review. The other cell is apparently quite carrier specific (SCS). The meaning of this is not at all clear, but its potential significance may somehow be related to a sort of "mirror image" relationship of the two cells. Thus, for example, in other experiments not discussed here, we have noted that the CRCS binds to 315 protein-coated plates, but as noted here counteracts a suppressive effect which is generated by cells which do not adhere to these plates. In contrast to SCS does not bind to 315 plates and yet, as noted here, appears to counteract a suppressor effect generated by cells which do adhere to 315 plates.(ABSTRACT TRUNCATED AT 400 WORDS)

Acceptor-suppressor T cell hybridoma with a receptor recognizing antigen-specific suppressor factor

An acceptor hybridoma with a receptor that recognizes the keyhole limpet hemocyanin (KLH)-specific suppressor T cell factor (KLH-TsF) was established after the fusion of C57BL/6 splenic T cells enriched with KLH-coated petri dishes. The cloned hybridoma (34S-281) could be specifically activated by stimulation with the conventional KLH-TsF or monoclonal KLH-TsF from three different hybridomas in the absence of the relevant antigen (KLH) and it started to produce another factor that suppresses the antibody response against DNP-KLH in a KLH-specific fashion. The KLH specificity of the TsF was required for activation. The new factor was found not to bind the KLH but to be absorbed with the KLH-TsF-producing hybridoma. It is thus strongly suggested that the acceptor site has a complementary structure (antiidiotype) for the KLH-TsF. Moreover, the idiotypic determinant on KLH-TsF was found to have a structure similar to that on some of the anti-KLH antibodies, since the acceptor hybridoma was specifically killed by the conventional anti-KLH antibodies and complement. Drawing on the above results, the idiotype-antiidiotype network in the conventional antigen system is discussed.

Cell-mediated immune response in Indian kala-azar and post-kala-azar dermal leishmaniasis

Cell-mediated immune (CMI) response in 16 Indian kala-azar (KA) and 12 post-kala-azar dermal leishmaniasis (PKADL) patients was studied in detail by in vitro lymphocyte transformation experiments and by in vivo skin testing. Peripheral blood lymphocytes of active KA patients failed to be stimulated by leishmania antigen. On the other hand, lymphocytes from a majority of the active KA patients could be stimulated by phytohemagglutinin. Active KA patients also failed to show delayed type hypersensitivity reaction to leishmanin, although 72% of them showed delayed type hypersensitivity to a purified protein derivative of tuberculin. Longitudinal studies indicated that antigen-specific CMI response usually appeared in treated KA patients after 12 to 20 weeks of antileishmanial drug therapy, although individual variations were noted. CMI response in PKADL patients was variable as about two-thirds of them showed positive sensitization to leishmania antigen in either in vivo or in vitro tests. Usually, patients with newly acquired PKADL exhibited better CMI response than those with chronic PKADL. However, lymphocytes from all of these patients could be stimulated normally by phytohemagglutinin. Results presented in this study show an impairment of CMI response in active KA which appears to be more specific to leishmania than generalized in nature. Moreover, restoration of specific T-cell responsiveness was aided by antileishmanial drug therapy which resulted in the reduction of antigenic load by parasite destruction and a concomitant decrease in circulating antibody levels, particularly that of the immunoglobulin G class. We suggest that the protection afforded by specific CMI response against Leishmania donovani infection may not be absolute and probably depends on other host-related factors leading to parasite destruction and patient recovery.

Genetic control of mouse antibody production to human thyroglobulin

Genetic control of immune responses in mice against human thyroglobulin was studied using the enzyme-linked immunosorbent assay and passive haemagglutination test. Our results revealed that mice of H-2a, H-2d, H-2q, H-2k and H-2r haplotypes were high responders for antibody production to human thyroglobulin, while mice of H-2b and H-2s haplotypes were low responders. High responsiveness to human thyroglobulin was transmitted to F1 mice in a dominant fashion. Study of the genetic mapping of the immune responses to human thyroglobulin using various congenic mice showed that I-A subregion gene(s) control the immune response to human thyroglobulin.

Excellent outcome after transplantation of renal allografts from HLA-DRw6-positive donors even in HLA-DR mismatches

The effect of the presence or absence in the donor of HLA-DRw6 on the survival of renal allografts was studied in 759 HLA-DRw6-negative recipients. The definition of HLA-DRw6 was consistent throughout the study period. 578 patients received an allograft with one HLA-DR mismatch and 181 an allograft with two HLA-DR mismatches. Allograft survival at 1 year was significantly better when the donors were HLA-DRw6-positive than when they were HLA-DRw6-negative, for both one-DR-mismatched (86% vs 65%) and two-DR-mismatched (85% vs 59%) allografts.

Activation of T cells in tumor-bearing mice

Subcutaneous transplantation of the syngeneic P815 mastocytoma in DBA/2J mice induced an activation of splenic T cells which resulted in a hyperresponsiveness of the tumor-bearing animal to the unrelated antigens pneumococcal polysaccharide (Pn) and sheep red blood cells (SRBC). These tumor-activated T cells appeared to increase the plaque-forming cell (PFC) potential of suboptimal numbers of spleen cells, caused normal spleen cells to express increased numbers of PFC, and produced lymphokine(s) which also increased PFC responses of normal splenocytes. The tumor-activated T cells responsible for stimulating normal splenocytes in an in vitro antibody response were shown to be Ly+2- cells. The activity of the tumor-activated T-cell supernatants was not genetically restricted and required additional Ly1 T cells in order to induce rigorously clean B cells to produce antibody. The T cells capable of stimulating non-specific antibody responses were also capable of slowing tumor growth when injected with tumor cells in normal recipient mice. These results suggest that T cells activated by tumor antigens release immunostimulatory lymphokines and, at the same time, are capable of leading to inhibition of tumor growth.

Use of anti-idiotype immunosorbents to isolate circulating antigen-specific T cell-derived molecules from hyperimmune sera

We immunized four different sheep with antigen-binding material found in the serum of BALB/c mice 4 days after primary immunization with sheep erythrocytes (SRBC). The resultant antibodies made by the sheep contained a specificity(ies) that appeared to react with a dominant idiotype present on SRBC-specific Lyt-2+ T cells. The antiserum made by the sheep markedly inhibited the formation of antigen-specific rosettes by SRBC educated T cells but did not inhibit T cells educated to other heterologous erythrocytes from forming crossreacting rosettes with SRBC or specific rosettes with the homologous erythrocytes. The "anti-Id serum" was depleted of all activity against known immunoglobulin isotypes and light chains and then was used to isolate antigen-binding molecules from mice that were hyperimmunized with SRBC. The ShId+ material so isolated could be divided into two main groups--one that expressed immunoglobulin determinants, and one that did not. The former represented 15-25% of the ShId+ protein isolated and comprised a minority of the anti-SRBC antibody in the anti-SRBC serum; the latter group of proteins bound sheep glycophorin specifically and expressed constant region determinants found on a number of other antigen-specific T cell factors. These experiments suggest that antigen-binding molecules made by T cells display much less heterogeneity than do antibodies and also show that the serum of hyperimmune mice contains significant amounts of T cell-derived antigen-specific immunoregulatory molecules.

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.

Molecular events in the processing of avidin by antigen-presenting cells (APC). III. Activation of T-lymphocyte lines and H-2 restriction are mediated by processed avidin associated with I-region gene products

We investigated the interaction between processed avidin (PA) and avidin-specific lines of T lymphocytes free of resident antigen-presenting cells (APC). We found that PA was able to replace the requirement for APC in the T-lymphocyte proliferative assay, only if the PA was associated with an Ia-positive moiety (IPM) supplied by the APC. In addition to supplying a necessary signal for a proliferative response to PA, IPM imposed H-2 restriction on the PA molecule. The association between PA and IPM was reversible and the two moieties could be physically separated and recombined. The results support a conclusion that major histocompatibility restriction of the interaction between T lymphocytes and APC is due to the association between processed antigen and an APC element containing I-region products.

Molecular events in the processing of avidin by antigen-presenting cells (APC). I. The immune response of T lymphocytes to avidin is regulated by H-2-linked Ir genes

The immune response of T lymphocytes to avidin was measured by proliferative assays, antibody production and delayed-type hypersensitivity. Mice of H-2k haplotypes were found to be low responders, whereas mice of other haplotypes, and particularly of H-2s, were high responders. Ir genes controlling this response were mapped to the I subregion of H-2. Helper T cells were found to be responsible for the Ir phenotype of antibody production. These results indicate the feasibility of using the avidin-biotin complex as a tool for studying molecular mechanisms by which antigens under Ir gene control are processed and presented to T lymphocytes.

Delayed-type hypersensitivity to hen egg-white lysozyme. I. The surface phenotypes of suppressor T cells induced by intravenous injection of lysozyme-modified spleen cells, and their molecular interactions

Suppressor T cells (Ts) induced by lysozyme-modified syngeneic lymphocytes were characterized. Hen egg-white lysozyme (HEL)-specific delayed-type hypersensitivity (DTH) was suppressed when HEL-induced Ts were transferred into naive mice. These HEL-induced Ts had surface markers of both Thy-1 antigen, and I-J gene products. The suppression of HEL-specific DTH was greatly increased, when these Ts had been enriched with HEL-coated petri dishes. Isolated anti-HEL antibodies from B10.BR or A/Sn mice were inoculated into rabbits to induce anti-cross-reactive idiotype (CRI) antibodies. The rabbit antisera were extensively absorbed with normal B10.BR or A/Sn immunoglobulins (Igs) and MOPC 104E ascites Igs to render them idiotype (Id) specific. Using these anti-CRI antibodies, we observed that these Ts possessed Id receptors on their cell surface. Results of both fluorescence techniques and cytotoxicity tests revealed that about 10% of the enriched T cells containing these Ts were Id positive. Moreover, these enriched T cells were substantially killed by anti-I-J antiserum plus complement. However, this killing was completely blocked by HEL antigen. These results suggest that both Id receptors and I-J gene products might be forming the same molecular complexes or might coexist in the vicinity of the molecule.

Fine antigenic specificity and genetic restriction of lysozyme-specific suppressor T cell factor produced by radiation leukemia virus-transformed suppressor T cells

Culture supernatants obtained from a radiation leukemia virus-transformed, hen egg-white lysozyme (HEL)-specific, suppressor T cell line are able, when injected into mice, to specifically suppress the anti-HEL antibody response. Suppression is observed on both primary and secondary anti-HEL antibody responses evaluated by direct and developed hemolytic plaque assays. Culture supernatants from this HEL-specific suppressor T cell line do not suppress the antibody response induced by a structurally related lysozyme, demonstrating the presence in the culture supernatant of a suppressor factor endowed with fine antigenic specificity. The suppressor factor is able to selectively suppress the anti-HEL antibody response induced by the N-terminal C-terminal peptide of the HEL molecule indicating that the fine specificity of this factor is restricted to an antigenic epitope present in this region of the HEL molecule. The suppressive activity is restricted by genes located within the H-2 complex and analysis of the suppression induced in recombinant mice demonstrates that the interaction between HEL-specific suppressor T cell factor and its cellular target requires identity in the I-J region of the H-2 complex.

A cloned cell line mediating natural killer cell function inhibits immunoglobulin secretion

We previously described a cloned cell line that combines information for a unique display of cell surface antigens and specialized function similar to activated natural killer (NK) cells. In addition to conventional cellular targets such as the YAC-1 and MBL-2 lymphomas, this cloned line also lysed lipopolysaccharide-activated B lymphocytes. To determine whether some NK cells can inhibit B cell function, we tested the ability of NK-like clones to suppress Ig secretion in vitro and in vivo. These cloned cells suppressed Ig secretion when they constituted as few as 0.2% of the total cell population and inhibition did not require identity at the H-2 locus. We suggest that some NK cells might recognize non-major histocompatibility complex gene products on activated B lymphocytes and lyse these cells, and this might represent a fundamental cell-cell interaction that regulates antibody secretion by activated B cells.

The use of unideterminant fragments of ferredoxin in the genetic mapping of determinant specificity of the immune response

The ferredoxin (Fd) molecule is a small non-mammalian immunogenic protein containing 55 amino acid residues with only two major antigenic determinants located with the NH2-terminal heptapeptide and the COOH-terminal pentapeptide. Selective enzyme cleavages of Fd with either trypsin or carboxypeptidase A result in the inactivation of the antigenic determinants by the removal of a tripeptide at the NH2-terminal and two amino acid residues at the COOH-terminal, effectively leaving 52 and 53 amino acid fragments respectively, each containing a single antigenic determinant. Fd digested with both enzymes yielded a 50 amino acid peptide with both determinants inactivated. Purity of these digests was assessed using monoclonal antibodies in standard and antigen-blocking ELISAs. The doubly digested peptide had virtually no reactivity with anti-Fd sera, reconfirming that the central cysteine-rich region is serologically silent. It was found that the sum of the reactivities of the N- and C-determinant-bearing peptides as equal to that of the native Fd and that the ratio of the reactivities could be used to assess determinant selectivity in the response to Fd in congenic recombinant strains of mice. This method was used in mapping the determinant selectivity in the antibody response to the MHC of mice to the left of the I-B subregion. Use of the B10.HTT strain indicated that separate genes mapping to the same subregion code for the magnitude of the antibody response and the determinant selectivity of the response.

Genetic control of the immune response to haemoglobin. IV. Ly-1+ T-cells and appropriate non-H-2 genes are required for in vitro responses to alpha- and beta-subunits of human adult haemoglobin

Experiments were conducted to determine if non-H2 gene effects could be demonstrated in mice which had been primed to either the alpha-subunit or beta-subunit of human haemoglobin. It was found that C3H.SW (H-2b) and Balb/c (H-2d) mice are low responder mice to alpha-chain of a haemoglobin when compared to H-2 identical B10 (H-2b) and B10.D2(H-2d) mice. B120.S and A.SW (both H-2s) are responsive to beta-chain challenge while Balb/c mice are low responders in contrast to high responder B10.D2 mice. Ly-1+ cells were demonstrated to be required (by cell depletion experiments) for an in vitro T-cell proliferative response to either subunit. In these experiments, Ly-2+ cells were not of crucial importance.

The role of H-Y as a minor transplantation antigen

H-Y antigen is expressed in mammals only by males, so that grafts of male tissue are rejected by females within certain highly inbred strains. H-Y antigen appears to be a simple, non-polymorphic antigen and the genetic control of anti-H-Y responses has been extensively studied. In this article Elizabeth Simpson discusses the many insights obtained.

Genetic control of the immune response to haemoglobin. II. Studies using purified alpha-chain and beta-chain as immunogens

Mice of independent haplotypes and several recombinant inbred strains were immunized with highly purified preparations of either the alpha-chain or beta-chain subunit of human adult haemoglobin. Cells from the sensitized lymph nodes were challenged in vitro with the appropriate subunit (or in some cases both chains) and cell proliferation assessed by 3H-thymidine incorporation. Mice of the H-2b and H-2d haplotypes were high responders to alpha-chain while mice of the H-2f, H-2j, H-2k, H-2r, H-2s, H-2u, and H-2v haplotype were low responders. the low responsivenesss of B10.A(4R) and B 10.MBR and high responsiveness of B10 indicated that the Ir gene(s) determining responsiveness to the alpha-chain subunit resides in the I-A subregion of the mouse major histocompatibility complex. Mice of the H-2d, H-2f, and H-2s haplotypes were high responders and H-2b, H-2j, H-2a, and H-2u haplotype mice were low responders to beta-chain. H-2k, H-2p, H-2r, and H-2v haplotype mice were intermediate responders to beta-chain. The low responsiveness of B10.S(8R) and B10.TL and the high responsivenes of B10.S(9R) mapped the Ir gene(s) to beta-chain to the I-A subregion. Data collected from challenging high responder cells with both subunit indicated that alpha-chain and beta-chain do not crossreact. These results are discussed in reference to earlier observations suggesting that the low responsiveness of some strains of mice to priming and challenging using the intact haemoglobin molecule might be due to a negative regulatory influence mediated by one of the subunits. In the absence of this influence these mice would respond normally.

Genetic control of the immune response to haemoglobin. I. Demonstration of separate genetic control of the responses to the alpha- and beta-subunits by in vitro lymphocyte proliferation

These studies were undertaken to analyse the genetic control of the immune response to an oligomeric protein and the role of individual subunits in the regulation of the response. Human adult haemoglobin (Hb) was selected as a model for these studies because it is a well-characterized protein and its antigenic structure is being determined in our laboratories. Mice of various congenic strains were immunized with Hb and the lymph node cells from Hb-primed mice were challenged in vitro with Hb, and its alpha-chain and beta-chains as well as an appropriate control antigen. Lymphocyte proliferation was determined by 3H-thymidine incorporation. The data collected indicated that mice of the H-2b and H-2d haplotypes were high responders while H-2k, H-2s, H-2q and H-2j haplotype mice were low responders to Hb. Studies with H-2 recombinant strains indicated that the immune response to Hb and its subunits is determined by genes in the I-A subregion and the D end of the H-2 complex. The significance of these findings in terms of control and regulation of the overall response to native Hb are discussed.

Regulation of delayed-type hypersensitivity (DTH) response to hen egg-white lysozyme (HEL)

Delayed-type hypersensitivity (DTH) can be demonstrated in A/J mice immunized with hen egg-white lysozyme (HEL) in complete Freund's adjuvant (CFA) by challenging primed animals in the ear with aqueous HEL. Normal A/J mice receiving soluble HEL derivative peptide, P-Ib, sequence 29-54 and 109-123 linked by a single S-S bond, 7 days prior to immunization with HEL showed much lower DTH response specific to the protein. The inhibition of DTH reactivity is due to active suppression and involves the generation of suppressor T-cells (Ts). Thus, the suppression induced with a single i.v. injection of P-Ib solution was able to be transferred into syngeneic recipients by the spleen cells from mice pretreated with P-Ib. These suppressor cells are T-cells, since their ability to suppress DTH is completely abrogated by treatment wit anti-Thy 1.2 and complement. Amongst HEL derivative peptides tested in the present study, only P-Ib could induce the tolerance.

Production of antigen-specific suppressive T cell factor by radiation leukemia virus-transformed suppressor T cells

Hen egg-white lysozyme (HEL)-specific suppressor T cells induced in C57BL/6 mice have been selected by sequential passage over plates coated with goat anti-mouse Ig and HEL. These suppressor T cells, 80% I-J+, were infected in vitro with radiation leukemia virus (RadLV/Nu1) and injected intravenously into sublethally irradiated syngeneic recipients. After 4-6 months, 6 out of 20 injected mice developed thymic lymphomas, which were maintained by transplantation into histocompatible hosts and subsequently established as permanent cell lines. Cells of these six thymomas were screened for the presence of Thy 1.2, Lyt 1, Lyt 2, I-Jb, and Ig cell surface antigens by direct or indirect immunofluorescence. One tumor (thymoma L4) was found to express the expected phenotype of suppressor T cells (Thy 1.2+, Lyt 2+, I-J+). High-speed supernatants of extracts obtained from L4 cells were able to induce HEL-specific suppression in a T cell proliferative assay, demonstrating the presence of an antigen-specific suppressive T cell factor.

The alloreactivity of human colostral T lymphocytes. II. Specific control of maternal anti-fetal mixed lymphocyte reactivity

Lymphocytes in human colostrum were examined for evidence of alloreactivity specifically directed against the paternal HLA haplotype. Such reactivity was detected using umbilical cord blood leukocytes as stimulator cells in the mixed lymphocyte reaction, but the responses were reduced when compared to those of the same patient's blood lymphocytes. Analysis of this defect determined that only colostral lymphocyte responses to neonatal alloantigens were impaired and that the phenomenon apparently depended on a non-adherent fetal leukocyte for its expression. Attempts to demonstrate directly colostrum or cord blood-derived cell-mediated suppression failed, and the results suggest that a classical T suppressor cell is probably not involved. These findings indicate that human colostrum contains anti-paternal T cell clones but their reactivity is specifically abrogated when cultured with fetal leukocytes.

Lymphocyte specificity to protein antigens. III. Capacity of low responder mice to beef cytochrome c to respond to a peptide fragment of the molecule

Lymph node cells derived from A.TH or A.TL mice primed with beef cytochrome c show striking patterns of reactivity when assayed in vitro for antigen-induced T cell proliferation. Whereas cells from A.TH mice respond specifically to beef cytochrome c or peptides composed of amino acids 1-65 and 81-104, cells from A.TL mice respond neither to beef cytochrome c nor to peptide 1-65, but proliferate following exposure to either peptide 81-104 or to a cytochrome c hybrid molecule in which the N-terminal peptide of beef (1-65) was substituted by a similar peptide obtained from rabbit cytochrome c. Thus, T cells from mice phenotypically unresponsive to beef cytochrome may, in fact, contain populations of lymphocytes capable of responding to a unique peptide, the response to which is totally inhibited when the same fragment is presented in the sequence of the intact protein.

Positive selection of major histocompatibility complex-restricted suppressor T cells bearing the predominant idiotype in the immune response to lysozyme

The lysozyme system provides an excellent model for studying the role of multiple major histocompatibility complex (MHC) genes in the induction and regulation of Ir-gene controlled immune responses. Immunization of H-2b mice leads to concomitant activation of helper and suppressor activities by different epitopes on hen egg-white lysozyme (HEL) and thus phenotype unresponsiveness to native HEL. HEL-specific suppressor T cells in C57BL/10 nonresponder mice show MHC restriction, because their enrichment on antigen-pulsed macrophage monolayers requires syngeneic macrophages as well as HEL. The expression of the selected suppressor function requires interaction between the restricted suppressor precursor cell and an HEL-triggered, suppressor-inducer T cell. The MHC-restricted suppressor precursors bear the predominant idiotype found on anti-HEL antibodies, whereas MHC-restricted helpers do not.

Differential major histocompatibility complex-related activation of idiotypic suppressor T cells. Suppressor T cells cross-reactive to two distantly related lysozymes are not induced by one of them

B10 (H-2b) mice are genetic nonresponders to hen egg-white lysozyme (HEL) and the distantly related human lysozyme (HUL). However, anti-HEL or anti-HUL primary antibody responses in vivo or in vitro can be obtained in B10 mice by immunization with the appropriate lysozyme coupled to erythrocytes. T cells able to suppress either anti-lysozyme plaque-forming cells (PFC) response are induced in B10 mice after immunization with HEL-complete Freund's adjuvant (CFA) or HUL-CFA. This cross-reactivity of HEL and HUL in the induction and the expression of suppressive activity is in marked contrast to their very low cross-reactivity at the PFC level. These results suggest that either HEL or HUL can stimulate a suppressor T cell which recognizes a particular epitope present on both lysozymes. Suppressor cells induced by HEL or HUL bear the same predominant idiotype found on the majority of anti-HEL antibodies, and on the small proportion of anti-HUL antibodies cross-reactive with HEL. B10.Q (H-2q) mice are responders in vivo to HEL-CFA, but not to HUL-CFA. In contrast to B10, HEL-CFA priming in B10.Q micr induces helper cells whereas HUL-CFA priming induces suppressor cells. These suppressor cells are cross-reactive with HEL and are fully able to suppress HEL-specific helper cells. The presence of HEL-specific suppressor cell precursors in B10.Q mice which are not activated by HEL, seems to implicate differential choice by the antigen presenting system as a basis for Ir gene control, rather than the absence of a regulatory cell type from the T cell repertoire.

Ir-gene control of T cell proliferative responses: two distinct expressions of the genetically nonresponsive state

Two distinct modes of unresponsiveness to hen egg-white lysozyme (HEL) have been demonstrated in the "nonresponder" C57BL/10 Sn (B 10) mouse strain at the level of T cell proliferation. The first is an apparent inability to respond to a peptide of HEL comprising 70% of the molecule, LII (amino acids 13--105, when HEL is used as immunogen. On its own, LII is capable of eliciting a strong response from B 10 draining lymph node cells, but this capacity is concealed when the whole molecule is used for immunization (by suppressor cell activity raised against another part of HEL, as described by Adorini et al., J.Exp. Med. 1979. 150: 293). In the B 10.A mouse, LII and HEL are equally immunogenic. The second is an actual failure, presumably unrelated to suppression, to contrive a response to particular determinants on HEL, demonstrated for certain epitopes on LII and LIII (amino acids 106--129). Such a failure to respond was maintained despite an increase in the immunizing dose of peptide to a molarity at which HEL itself could overcome Ir gene control. B 10 cells responding to a high dose of HEL, or to the immunogenic lysozyme from ring-neck pheasant, were also unable to respond to these epitopes. These deficits in responsiveness appear to be characteristic manifestations of the relevant haplotype of the major histocompatibility complex. They may not only reflect the balance between competing T cell subpopulations, but also the constraints of associative recognition that may underlie the presentation of particular antigenic specificities.

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.

Multiple H-2 and non-H-2 genes controlling the antilysozyme response: alternative gene constellations can lead to responsiveness

Mice carrying the H-2b and H-2s haplotypes are genetically nonresponsive to hen egg-white lysozyme (HEL). Analysis of the anti-HEL response patterns of F1, F2 and backcross progeny showed that responsiveness was dominant and H-2 linked. From plaque-forming cell and serum assays in intra-H-2 recombinant mice, it was established that two I loci were implicated, the possession of either leading to responsiveness to HEL. One of the I genes maps in I-A, and the second in I-C, S or G. While the nonresponse phenotype was determined by the H-2 haplotype, there were codominant non-H-2 genes which contributed to a severe reduction in the level of antibody produced in responder strains. A model is presented attributing the outcome of an encounter with HEL to the regulatory balance of helper and suppressor T cells, which have been activated by different subregions of the major histocompatibility complex.

Basic strategies of the immune system in the regulation of antibody response

Three major regulatory mechanisms operating in the control of antibody response have been examined: 1. antibody feedback; 2. T cell regulation (I. regulatory interactions among T cell subsets, II. H-2 linked Ir gene control of T cell function, III. regulatory role of antigenic epitopes in T cell subsets induction); 3. idiotypic network. Analysis of the results of obtained in the lysozyme system together with available data in the literature have permitted the delineation of a model of antigen-triggered events involved in the regulation of antibody response. The basic feature of the proposed model is the integration of two major specific communication systems among lymphocytes engaged in the antibody response: antigen bridge and idiotypic complementarity.

Delayed-type hypersensitivity to influenza virus. Induction of antigen-specific suppressor T cells for delayed-type hypersensitivity to hemagglutinin during influenza virus infection in mice

Mice infected with A/England/939/69 X A/Puerto Rico/8/34 (Rec 31) influenza virus by aerosol develop significantly lower levels of delayed-type hypersensitivity (DTH) to A/Hong Kong/1/68 X A/Puerto Rico/8/34/ (X31) virus compared to uninfected mice. The suppression of DTH to the hemagglutinin appears to be mediated by suppressor T cells which carry Lyt-1 membrane antigen marker, and not by sy serum antibody. The suppressor T cells for DTH induced by Rec 31 virus (H3N1) infection suppress the DTH response to the variants of the H3 subtype of influenza viruses, but have no effect on the DTH responses to A/Puerto Rico/8/34 virus (H0N1), a B influenza virus or the matrix protein of type A influenza virus. Suppressor T cells for DTH appear 2 wk after infection and are detectable in the spleen for at least 40 d thereafter. T-helper cells for antibody response to hemagglutinin are induced concomitantly with the T-suppressor cells for DTH. Possible implications of the present findings on the regulation of the immune response to viral infection are discussed.