Genetic control of immune responses in vitro. 3. Tolerogenic properties of the terpolymer L-glutamic acid 60-L-alanine30-L-tyrosine10 (GAT) for spleen cells from nonresponder (H-2s and H-2q) mice

Sleep therapeutics and neuropsychiatric illness

Alterations in sleep are extremely common in patients with neuropsychiatric illness. In addition, sleep disorders such as insomnia, obstructive sleep apnea, rapid eye movement sleep behavior disorder, and circadian rhythm disorders commonly occur at a rate greater than the general population in neuropsychiatric conditions. Historically, sleep problems have been viewed as symptoms of associated neuropsychiatric disorders. However, there is increasing evidence suggesting a complex inter-relationship with possible bidirectional causality. The inter-relatedness of these conditions represents an opportunity for understanding mechanisms and improving clinical treatment. To the extent that sleep problems affect neuropsychiatric conditions, it may be possible to address sleep problems and have a positive impact on the course of neuropsychiatric illnesses. Further, some treatments for sleep disorders have direct effects on neuropsychiatric illnesses that may be unrelated to their effects on sleep disorders. Similarly, neuropsychiatric conditions and their treatments can affect sleep and sleep disorders. This article reviews available evidence on the effects of therapies for sleep disorders on neuropsychiatric conditions and also secondarily considers the impacts of therapies for neuropsychiatric conditions on sleep. Primary goals of this review are to identify gaps in current research, to determine the extent to which the cross-therapeutic effects of these treatments help to elucidate therapeutic or pathological mechanisms, and to assist clinicians in optimizing therapeutic choice in patients with sleep disorders and neuropsychiatric conditions.

Flow cytometric analysis of lymphocyte subsets of mice maintained on an ethanol-containing liquid diet

Alcoholic patients often have impaired immune function, yet little is known about the precise mechanism(s) of this impairment. We have previously shown that ethanol consumption by mice alters copolymer-specific humoral and cellular immune responses. In this study, we asked whether alcohol consumption by mice would phenotypically alter lymphocyte populations. Female C57BL/6 mice were fed a nutritionally complete liquid diet containing 35% ethanol-derived calories for up to 8 days. As controls, mice either were fed a liquid control diet that isocalorically substitutes sucrose for ethanol or remained on a standard solid diet and water ad libitum. Although mice fed ethanol-containing liquid or pair-fed control liquid diets have decreased numbers of spleen cells compared with solid diet controls, only the ethanol-containing diet allowed normally nonresponder C57BL/6 spleen cells to make antibody responses to the poly(Glu50Tyr50) synthetic copolymer antigen. Flow cytometric analysis of splenic lymphocyte populations of mice on the ethanol-containing diet shows an increase in the relative proportion of T-lymphocytes as compared with mice on either solid or liquid control diets. No such change is seen for either B-cell or natural killer cell populations in these same mice. Both liquid control and liquid ethanol diets caused a slight decrease in the CD4:CD8 ratios of splenic T-lymphocytes. We see the relative percentage of T-cells bearing the alpha beta T-cell receptor (TcR) increases in the spleens of liquid ethanol diet mice; a smaller increase TcR alpha beta usage is seen in the spleens of liquid control mice, compared with solid diet mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Alteration of copolymer-specific humoral and cell-mediated immune responses by ethanol

Excessive alcohol consumption represents a major human health threat. The frequency and severity of infections in alcoholics is often pronounced, suggesting impaired immune function in these patients. The precise effect of ethanol on cells of the immune system is poorly understood. We have previously shown that synthetic copolymers of L-amino acids, GT and GAT, are powerful tools for clarifying the role of regulatory T-cells in both cell-mediated and humoral immunity in inbred mouse strains. We asked whether these same antigens would have application to a murine model of ethanol consumption. In this study, female mice were placed on a nutritionally complete liquid diet containing 35% ethanol-derived calories. As control, mice either were placed on a liquid control diet that isocalorically substitutes sucrose for ethanol or remained on a solid diet consisting of standard laboratory chow and water ad libitum. Our data show that the liquid ethanol diet severely inhibits two measures of cell-mediated immunity, the ability of responder B6 mice to make an anti-GAT delayed hypersensitivity and GAT-specific T-cell proliferative responses as compared with pair-fed liquid control diet or solid diet controls. On the contrary, this liquid ethanol diet does not significantly impair humoral immunity; it allows nonresponder C57BL/6 or C3H/HeN mice to respond in vivo to GT immunization. These findings suggested to us that the effect of ethanol may occur prior to antigenic stimulation, and this was confirmed by in vitro immunization.

Phenotype of lymphocytes mediating copolymer-specific humoral immunity in ethanol-consuming C57BL/6 mice

Little is known about the mechanisms of impaired immune function in alcoholic patients. We have previously shown that ethanol consumption by mice alters copolymer-specific humoral and cellular immune responses. Does ethanol consumption eliminate suppressor T cells, allowing nonresponder mice to make humoral immune responses to poly(Glu50Tyr50) (GT)? Female C57BL/6 mice were fed a nutritionally complete liquid diet containing 35% ethanol-derived calories for up to 33 days. Control mice were fed an isocaloric control liquid diet or remained on a solid diet and water. Mice fed the ethanol-containing diet made GT-specific plaque-forming cell (PFC) responses, whereas mice fed liquid control or solid diets did not. Lymphocytes from ethanol liquid diet-consuming mice helped splenocytes from either solid or liquid control mice to make a GT-specific PFC response. The cells mediating help were nylon wool nonadherent, CD4-bearing T cells. These findings suggest that ethanol does not eliminate copolymer-specific suppressor cells, but instead alters the functional capability of helper T cells for humoral immune responses.

Epitope-specific regulation in Ir gene systems. I. Conditions for the induction of epitope-specific suppressors to poly(Glu60Ala30Tyr10)

Injection of responder mice with poly(Glu60Ala30Tyr10) (GAT) followed by immunization with GAT-methylated bovine serum albumin (GATMBSA) selectively suppresses anti-MBSA plaque-forming cell (PFC) and delayed hypersensitivity (DTH) reactions. Conversely, MBSA injection followed by GATMBSA immunization suppresses anti-GAT PFC and DTH, while anti-MBSA responses remain intact. Suppression occurs for doses of antigen which are optimally immunogenic. The suppression is specific and does not act in a bystander fashion. These results demonstrate that epitope-specific regulation is reciprocal, is not limited to humoral responses, and is not limited to molecules of low molecular weight.

Induction by monoclonal anti-idiotypic antibodies of an anti-poly(Glu60 Ala30 Tyr10) (GAT) immune response in GAT-responder and GAT-nonresponder mice

Two different monoclonal anti-idiotypic (Id) antibodies, HP-Id20 and HP-Id22, recognizing two discrete idiotopes characteristic of the anti-poly(Glu60 Ala30 Tyr10) (GAT) response were used to immunize BALB/c (GAT-responder) and DBA/1 (GAT-nonresponder) mice. The monoclonals were injected either copolymerized with keyhole limpet haemocyanin or polymerized with glutaraldehyde. The specific response was studied by two assays: (a) inhibition of binding of monoclonal anti-GAT antibody G5Bb2-2 to HP-Id20 and HP-Id22 and (b) GAT binding assays. In BALB/c GAT-responder mice, HP-Id20 and HP-Id22 immunization led to the preferential stimulation of immunoglobulin idiotypically related to anti-GAT antibodies (Ab1') and expressing anti-GAT activity. The results obtained with BALB/c nu/nu mice indicated that this response is T-cell-dependent. By means of the same experimental protocol GAT-nonresponder animals could be induced to produce anti-GAT antibodies after HP-Id immunization. This last result indicates that anti-Id immunization can bypass Ir gene control and does not preferentially stimulate the induction of GAT-specific T suppressor cells.

Gain/loss of poly(Glu50Tyr50)/poly(Glu60Ala30Tyr10) responsiveness in the bm12 mutant strain

The development of inbred strains of mutant mice has proven useful in ascribing specific gene functions to particular genetic loci within the regions and subregions of the H-2 complex. The B6.C-H-2bm12 (bm12) strain is of particular interest in that, compared to parental C57Bl/6Kh (B6) mice, it bears a presumptive single gene mutation altering the Ab beta chain encoded by the I-A subregion. Our data show that bm12 mice have gained the ability to respond to poly(Glu50Tyr50)(GT) and have lost the ability to make plaque-forming cell or delayed-type hypersensitivity responses to the closely related copolymer, poly(Glu60Ala30Tyr10)(GAT), although retaining the ability to mount a GAT-specific T cell proliferative response. This is in sharp contrast to the parental B6 strain, which is a GT nonresponder and a GAT responder. Thus, this study is the first to report the establishment of responder status as a consequence of mutation. Possible mechanisms accounting for the gain/loss of GT/GAT responsiveness in the context of a two-step helper T cell model are discussed.

Strain differences in lymphocyte responses and in vitro suppressor cell induction between Schistosoma mansoni-infected C57BL/6 and CBA mice

Splenic lymphocyte blastogenic responses to mitogens and antigens were compared in Schistosoma mansoni-infected C57BL/6 and CBA mice. At 1 and 2 weeks of infection, elevated responses to phytohemagglutinin (PHA) were noted in C57BL/6, but not in CBA cultures. During the same period, elevated responses to lipopolysaccharide were observed in cultures from CBA, but not from C57BL/6 mice. Responses to both mitogens were depressed in both strains later in infection. The magnitude of antigen-specific responses was greater in CBA than in C57BL/6 cultures. A cercarial extract (CE) induced significant suppressor cell activity in normal C57BL/6 cell cultures as assessed by inhibition of syngeneic cell responsiveness to PHA. CE did not induce suppressive activity in CBA cultures. CE-induced suppression was unaffected by adherent cell removal, but was sensitive to anti-Thy 1.2 plus complement treatment. CE also directly inhibited PHA-stimulated C57BL/6 cell cultures, but enhanced cultures of CBA mice. The significance of these findings is discussed in relation to the relative strain differences seen in antigen-specific lymphocyte proliferation and the levels of protection induced after immunization with irradiated cercariae.

Selective expression of antibody classes and contact sensitivity affected by genes in the major histocompatibility complex

This report describes IgM, IgG and IgE antibody and contact sensitivity responses of strains of mice congenic at the major histocompatibility complex (MHC) to skin painting with picryl chloride or oxazolone. B10 had low responses of all classes to picryl chloride. This was also reflected by the DNA synthesis occurring in their draining lymph nodes after painting. B10BR were high responders to picryl chloride for all classes but B10A and B10D2 were high responders for all classes except IgE. This presents evidence that genes in the MHC can selectively control antibody classes. The contact sensitivity response of the congenics to oxazolone confirmed the low previously described responsiveness of B10 mice. Antibody responses to oxazolone (agglutinin and reagin) were low for all congenics with B10 backgrounds.

Stimulation of specific suppressor T cells in newborn responder mice by the terpolymer L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT)

The effects of immunization with the terpolymer of L-glutamic acid60-L-alanine40-L-tyrosine10 (GAT), the copolymers of L-glutamic acid60-L-alanine40 (GA) and of L-glutamic acid50-L-tyrosine50 (GT), were compared in adult and newborn BALB/c and BALB.B mice. as expected, BALB/c (H-2d) and BALB.B (H-2b) adult mice were responders to GAT and GA and nonresponders to GT, which induced suppressor T cells in BALB/c but not in BALB.B mice. in contrast, newborn mice expressed different phenotypes. Two-week-old mice developed responses to GAT, GA and GT-complexed methylated bovine serum albumin, but immunization at birth with these copolymers induced a cross-reactive tolerance in both strains. Neonatal GAT tolerance could be transferred in adult and involved suppressor T cells in the two inbred strains, whereas the GT-specific immune suppression was not demonstrable in newborn BALB/c mice. The significance of these data to our understanding of the regulation of specific immune response and tolerance is discussed.

L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT): A probe for regulatory mechanisms in antibody responses

The synthetic random terpolymer of L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT) has been used as a probe to investigate regulatory mechanisms in antibody responses in tissue culture systems. In this brief review, the mechanisms of H-2 linked Ir gene control of antibody responses to GAT and genetic restrictions governing Mphi-immune T cell interactions in antibody responses to GAT are summarized.

Antigen-specific T-cell-mediated suppression. I. Induction of L-glutamic acid60-L-alanine30-L-tyrosine10 specific suppressor T cells in vitro requires both antigen-specific T-cell-suppressor factor and antigen

A combination of in vitro and in vivo techniques were used to explore the mode of action of both crude and purified suppressive extracts specific for the random copolymer L-giutamic acid(60)-L-alanine(30)-L-tyrosine(10) (GAT- T(s)F) obtained from nonresponder DBA/1 (H-2(q)) mice. Normal DBA/1 spleen cells were incubated under modified Mishell-Dutton culture conditions for 2 days together with crude or purified GAT-T(s)F, and in the presence or absence of free GAT. These cells were then washed extensively and 3 x 10(6) viable cells transferred to syngeneic recipients, which were challenged at the same time with the immunogenic form of GAT complexed to methylated bovine serum albumin (GAT-MBSA). GAT-specific IgG plaque-forming cells (PFC) in the spleen were assayed 7 days later. In agreement with earlier in vitro studies on the action of GAT-T(s)F, it was demonstrated that under these conditions, low concentrations of GAT-T(s)F stimulated the development of cells which, aider transfer, are able to suppress the GAT PFC response to GAT-MBSA. The cells responsible for this suppression were shown to be T lymphocytes by using nylon wool-purified T cells for suppressor cell induction and by eliminating suppressive activity in cells cultured with crude GAT-T(s)F by treatment with anti-Thy 1.2 plus C before transfer. The suppressor T cells act in a specific manner failing to suppress significantly either anti-sheep erythrocyte or trinitrophenyl-ovalbumin primary PFC responses. For the induction of GAT-specific suppressor T cells in culture, a moiety bearing H- 2(K(q) or I(q)) determinants and also GAT, either bound to the crude GAT- T(s)F or added in nanogram amounts to antigen (GAT)-free purified GAT-T(s)F, were both required.

Specific enrichment of the suppressor T cell bearing I-J determinants: parallel functional and serological characterizations

A simple procedure to enrich the antigen (keyhole limpet hemocyanin, KLH)-specific suppressor T cell was described. The suppressor T cell from KLH)-immunized mice specifically bound to the KLH-coated Sephadex G-200 column at 37 degrees C, and was eluted from the column by cold (0-4 degrees C) medium. The helper T cell did not bind to the column under the identical condition. The suppressor T cell thus obtained had 100 times as potent suppressor activity as the original spleen cells in in vivo and in vitro secondary antibody responses against a hapten coupled to KLH. This procedure also enriched the cells bearing I-J determinants and Lyt-2,3 alloantigens, allowing us to study the phenotypic expressions on the suppressor T cell by direct serological procedures as well as by the use of the fluorescence activated cell sorter. Parallel functional and serological analyses indicated that the antigen-specific suppressor T cell belongs to a population of I-J+, Lyt-2+,3+ and Fc R- T cells.

Immunosuppressive factor(s) specific for L-glutamic acid50-L-tyrosine50 (GT). III. Generation of suppressor T cells by a suppressive extract derived from GT-primed lymphoid cells

Injection of mice with L-glutamic acid50-L-tyrosine50 (GT)- or L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT)-specific suppressor T-cell factor (GT-TsF or GAT-TsF) up to 5 wk before antigenic challenge challenge suppresses GT-methylated bovine serum albumin (MBSA) and GAT-MBSA plaque-forming cells responses. T suppressor cells are responsible for the suppression induced by the suppressive extract as demonstrated by adoptive transfer and sensitivity to anti-Thy-1 and complement treatment. We conclude that suppressive extract induces specific suppressor T cells. The material responsible for generation of suppressor T cells is a product of the I subregion of the H-2 complex. We have excluded that suppressive quantities of antigens are present in the extract. A/J mice, which can neither be suppressed by GT nor make GT-TsF can be suppressed by BALB/c GT-tsf. Spleen cells from BALB/c GT TsF-primed A/J mice can adoptively transfer suppression to normal syngeneic recipients. A/J mice appear to be genetically defective in cells involved in factor production. These results are discussed in the light of a two-step model for induction of antigen-specific suppressor cells.

Restriction of primary responses to the IgG class and dependency of IgM responses on secondary immunization for the copolymers of L-glutamic acid, L-tyrosine, and L-alanine

Primary responses to the linear polymers of L-glutamic acid, L-tyrosine, and L-alanine are restricted to the IgG class of antibodies. The appearance of specific IgM antibodies against these antigens is dependent upon secondary immunization, in contrast to many classical antigenic systems. The presence of an IgM response was verified by a direct plaque-forming cell assay, the inhibition of direct plaques by an antiserum specific for mouse micron-chain, and the physical separation of IgM and IgG GAT-specific antibodies by gel filtration. Preimmunization of the appropriate nonresponder strain with GAT or GT inhibits both the secondary IgM and IgG responses to GAT-MBSA and GT-MBSA, respectively. The tolerance observed is due to the induction of suppressor cells as demonstrated by cell transfer experiments.

The kinetics of IgG and IgM antibody-forming cells in ACI and F344 rats immunized with poly(glu52lys33tyr15)

The cellular kinetics of antibody production in high and low responder rats immunized with poly(Glu52Lys33Tyr15) or with poly(Glu52Lys33Tyr15)/MeBSA were characterized: serum antibody and IgG and IgM antibody-forming cells in the spleen and in selected lymph nodes were assayed in male and female rats following immunization by several routes. Aggregation of the antigen with MeBSA enabled the poorly responding F344 rats to produce antibody, which was almost exclusively IgG. High responder ACI rats, under the same conditions, produced antibody of both IgG AND IgM classes. These data suggest that in low responders one defect, possibly at the T-cell level, can be overcome by aggregation but that a second defect, involving the regulation of IgM production, still exists.

Immunosuppressive factor(s) extracted from lymphoid cells of nonresponder mice primed with L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT) III. Immunochemical properties of the GAT-specific suppressive factor

The GAT-specific suppressor T-cell factor (GAT-TsF) extracted from lymphoid cells from GAT-primed, nonresponder DBA/1 mice has been partially characterized. It is a protein that has affinity for GAT and determinants encoded by the I region of the H-2 complex. On the basis of specificity and avidity, GAT-TsF resembles anti-GAT-MBSA antibodies produced by DBA/1 mice in spite of the fact that it is too small to be classical antibody and has no constant-region determinants of heavy or light chains. Further, GAT or a fragment of GAT is associated with the GAT-TsF. GAT-TsF has been partially purified from the crude extract by absorption to GAT-Sepharose and elution with 0.4 to 0.6 KCl. GAT-TsF purified on the basis of its affinity for GAT bears I-region determinants but not detectable GAT or GAT fragment.

Immunosuppressive factor(s) extracted from lymphoid cells of nonresponder mice primed with L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT) II. Cellular source and effect on responder and nonresponder mice

The synthetic terpolymer of L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT) fails to stimulate development of GAT-specific antibody responses in nonresponder strains of mice, but does stimulate the development of GAT-specific suppressor T cells that inhibit the development of normal anti-GAT antibody responses to GAT complexed to methylated bovine serum albumin (GAT-MBSA). Furthermore, extracts prepared from lymphoid cells of GAT-primed, but not control, nonresponder mice inhibit the development of antibody responses to GAT-MBSA by normal nonresponder mice. This suppression is specific, dose-dependent, and can be readily analyzed in vitro. The suppressive factor is a T-cell product. An extract from GAT-primed DBA/1 mice inhibits the response to GAT-MBSA by spleen cells from histoincompatible strains of mice that are nonresponders to GAT, but not strains that are responders to GAT.

In vitro studies on H-2 linked unresponsiveness to synthetic polypeptide antigens. II. Induction of suppressor cells in both responsive and unresponsive mice to (T,G)-A-L and GAT;

Antigen-specific T-suppressor cells can be induced in vitro from unprimed lymphoid cells of high responder (C57BL/10) and low responder (B10.Br, B10.A, CBA) mice to (T,G)-A-L and high responder (B10, B10;A) and non-responder (B10.G, DBA/1) mice to GAT10. The suppressor cells induced from high and low or non-responder mice appear identical in efficiency, in the antigen concentration required for induction and in their induction kinetics.

In vitro studies on H-2 linked unresponsiveness. 1. Normal helper cells to (T,G)-A-L and GAT in low and non-responder mice

Lymphoid cells from unprimed high responder (C57BL/10) and low responder mice (B10.Br, B10.A, CBA) to (T,G)-A-L and high responder (B10, B10.A) and non-responder (B10.G, DBA/I) mice to GAT can be induced to form antigen specific T-helper cells in vitro under identical culture conditions. The helper cells induced from high and low or non-responder mice appear to be identical in efficiency, antigen concentration requirement for induction and induction kinetics.

Determinants of antigenic molecules responsible for genetically controlled regulation of immune responses

The ability of mice bearing the H-2S haplotype to develop helper responses to the random copolymer of Glu,Ala while they developed suppressor responses to the terpolymer of Glu,Ala,Tyr suggested the crucial role of tyrosine in these peptides. On the basis of various considerations, it was postulated that many of the tyrosine residues in Glu,Ala,Tyr would be localized at the NH2-terminal end of the molecule. To verify this hypothesis, a block terpolymer composed of a short sequence of homopolymer tyrosine covalently bound to the random copolymer of Glu,Ala was synthesized. The present studies, using this block terpolymer, demonstrated that the chemical determinants stimulating helper and suppressor responses are distinct and can be present simultaneously in the same molecule. Thus, addition of COOH-terminal tyrosine residues to the Glu,Ala polypeptide converted this immunogenic molecule to an immunosuppressive molecule in mice bearing the H-2S haplotype. The mechanism by which these short sequences of tyrosine influence H-2-linked immune responses remains to be determined.

Genetic control of specific immune suppression. III. Mapping of H-2 complex complementing genes controlling immune suppression by the random copolymer L-glutamic acid50-L-tyrosine50 (GT)

Earlier studies from our laboratory demonstrated that the terpolymer of L-glutamic acid, L-alanine, and L-tyrpsine (GAT) stimulated the development of T cells capable of specifically suppressing the antibody responses in vivo and in vitro of nonresponder strains (bearing the H-2(s), H-2(q), and H-2(p) haplotypes) to GAT complexed with an immunogenic carrier, methylated bovine serum albumin, MBSA (1,2). We then extended these findings to another antigen, the copolymer of L-glutamic acid and L-tyrosine (GT). None of 19 inbred or congenic resistant mouse strains developed antibody responses to GT after immunization with this synthetic polypeptide in adjuvants. All the strains investigated, however, developed IgG plaque-forming cells (PFC) primary responses to GT complexed with MBSA (3). This permitted us to determine that: (a) preimmunization with GT suppressed the response to GT-MBSA in certain but not in all strains; (b) the suppression could be transferred by thymocytes and spleen cells from GT-primed animals; (c) the development of GT-specific suppressor cells is under dominant control of H-2- linked gene(s) which have been designated specific immune suppressor genes (Is genes); (d) the Is genes are antigen specific since GAT-MBSA responses are suppressed by GAT in strains carrying the H-2(q) haplotype, while GT-MBSA responses are not suppressed by the related polymer GT in these same strains (3,4). The experiments reported in this study map the Is genes responsible for GT-specific suppression within the H-2 complex. The data indicate that the K and D loci are not concerned with GT-specific suppression, and that this phenomenon is controlled by complementing or interacting genes which map on either side of cross-over events between the IB and IC subregions.

Genetic control of specific immune suppression. IV. Responsiveness to the random copolymer L-glutamic acid50-L-tyrosine50 induced in BALB/c mice by cyclophosphamide

Previous reports from our laboratory have demonstrated the stimulation of specific suppressor T cells in genetic nonresponder mice after immunization with the terpolymer of L- glutamic acid, L-alanine, and L-tyrosine (GAT) (1,2) and with the copolymer of L-glutamic acid and L-tyrosine (GT) (3-5). These findings raise two important questions: (a) do the specific suppressor T cells inhibit an antibody response which would otherwise develop in nonresponder mice; and, (b) can specific helper T cells inhibit an antibody response which would otherwise develop in nonresponder mice; and, (b) can specific helper T-cell activity be detected in these animals. Responsiveness appears to be completely dominant over suppression in (responder x suppressor)F(1) hybrids, therefore, we have been unable to detect suppressor cells in these hybrids after conventional immunization with GAT (2). However , using special conditions of antigen administration, GAT helper activity could be demonstrated in nonresponder DBA/1 ("suppressor") mice. Thus, GAT-specific helper activity was not detected in these nonresponder animals after immunization with GAT irrespective of the adjuvant used, but could be stimulated by macrophage-bound GAT or by GAT complexed with methylated bovine serum albumin GAT-MBSA (6). In the current report we have taken advantage of the fact that suppressor T-cell activity is more sensitive to cyclophosphamide treatment than T-cell helper activity (7) to demonstrate the presence of GT-specific helper activity in "nonresponder" BALB/c mice. We describe: (a) the dose of cyclophosphamide and conditions of treatment which inhibits the well-documented stimulation of specific suppressor T cells in BALB/c mice injected with GT previous to immunization with GT-MBSA, and (b) the ability of cyclophosphamide to permit the development of primary PFC responses to GT in these "nonresponder" mice. These cyclophosphamide-induced responses are not characterized by the high levels of antibody detected in genetic responder animals.

Genetic control of specific immune suppression. I. Experimental conditions for the stimulation of suppressor cells by the copolymer L-glutamic acid50-L-tyrosine50 (GT) in nonresponder BALB/c mice

In the present studies we have confirmed that the random copolymer of L-glutamic acid50-L-tyrosine50 (GT) fails to induce an antibody response in a large number of inbred strains of mice. Nevertheless, GT complexed to methylated bovine serum albumin (MBSA) elicits a GT-specific IgG PFC response in vivo. Furthermore, injection of BALB/c mice with 10 to 100 mug of GT specifically decreases their ability to develop anti-GT PFC responses to a subsequent challenge with GT-MBSA. GT-specific tolerance can be transferred to normal, syngeneic recipients by spleen cells or thymocytes of GT-primed animals. These results indicate that the stimulation of suppressor cells can be observed in nonresponder mice with another synthetic polypeptide besides GAT. Various parameters of GT-specific immunosuppression in BALB/c mice are described. The application of these techniques to the study of the genetic factors controlling the stimulation of specific immune suppression is discussed.

Genetic control of specific immune suppression. II. H-2-linked dominant genetic control of immune suppression by the random copolymer L-glutamic acid50-L-tyrosine50 (GT)

Several inbred as well as congenic resistant strains of mice, which fail to respond to the random copolymer of L-glutamic acid50-L-tyrosine50 (GT), were shown to develop specific PFC responses when stimulated by GT complexed to an immunogenic carrier such as methylated bovine serum albumin (MBSA). In these studies we have found that GT preimmunization has a tolerogenic effect on the response to GT-MBSA in some mouse strains; whereas in other strains of mice, GT fails to inhibit the GT-MBSA response. We may, therefore, conclude that immune suppression cannot account for nonresponsiveness in all cases. The development of specific immune suppression in response to GT was shown to be inherited as a dominant trait in F1 hybrids resulting from the mating of suppressor with nonsuppressor strains. This trait is, therefore, under the control of a gene or genes that we have designated as specific immune suppression gene(s) Is genes. The strain distribution of GT induced suppression demonstrates that Is genes are coded for in the H-2 complex. Furthermore, immune suppression by the two related copolymers, GT and GAT, are distinct in different strains of mice. The significance of these data for our understanding of the regulation of the immune response is discussed.

Genetic control of immune responses in vitro. VI. Experimental conditions for the development of helper T-cell activity specific for the terpolymer L-glutamic aicd60-L-alanine30-L-tyrosine10 (GAT) in nonresponder mice

Mice which are genetic nonresponders to the random terpolymer of L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT) not only fail to develop GAT-specific antibody responses when stimulated with soluble GAT either in vivo or in vitro, but develop GAT-specific T cells which suppress the GAT-specific plaque-forming cell response of normal nonresponder mice stimulated with GAT complexed to methylated bovine serum albumin (MBSA).Thus, both responder and nonresponder mice have T cells which recognize GAT. However, nonresponder mice can develop GAT-specific helper T cells if immunized with GAT bound to MBSA or to macrophages. The relevance of Ir gene-controlled responses is discussed.

Deregulation of mouse antibody-forming cells in vivo in cell culture by streptococcal pyrogenic exotoxin

An unregulated, elevated rebound of antibody levels in rabbits was shown to follow late (10 to 15 days) after steptococcal pyrogenic exotoxin (SPE)-induced immunosuppression. Because of that result we have suggested that SPE acts by preferentially inhibiting a regulatory cell which normally limits the extent of full expression of antibody formation by B-cells. We are currently testing this hypothesis in mice. NIH (Swiss Webster) mice (+/+) or NIH (Swiss Webster) mice heterozygous (+/nu) for the mutant athymic nude gene and phenotypically normal showed an elevated plaque-forming cell (PFC) response to sheep erythrocytes (SE) late (10 to 15 days) after immunosuppressive SPE treatment similar to that described in rabbits. Homozygous nude mice (nu/nu) that are phenotypically athymic normally show a reduced early (4 day) PFC response to SE (a T-cell-dependent antigen) as compared with +/nu littermates or +/+ parent strain mice. This cryptic early 4-day response was improved by injection of purified endotoxin (a B-cell mitogen), but these relatively elevated nude PFC responses had decreased to normal control (SE only)nude PFC levels before 10 days. In similar SE-injected nude mice treated instead with SPE, no elevation at 4 days was observed and, more pertinently, the late (10 to 15 day) elevated rebound of PFC levels observed in normal response controls (+/nu or +/+) was not observed. Similar experiments were subsequently conducted in Marbrook-type spleen PFC cultures during periods of 12 days. The results of these experiments paralleled the in vivo results above, and in addition showed that SPE induced a large proliferation of either +/+ or +/nu cells (T-and B-cells) in culture but had no such effect on nu/nu cells (B-cells) in culture. Purified endotoxin, the Bcell mitogen, had a better sparing effect on nu/nu cells in this respect. These results are consistent with our premise that SPE inhibits preferentially the function of a regulator of the antibody response. The regulator appears to be a T-cell and is likely a suppressor T-cell.