Showing papers on "Immune tolerance published in 1985"

Murine models of systemic lupus erythematosus.

Abstract: Publisher Summary This chapter reviews the histopathologic, serologic, lymphocytic, virological, hormonal, and genetic characteristics of murine models of systemic lupus erythematosus (SLE). The pathogenetic mechanisms underlying murine SLE are highly complex, apparently well-programmed genetically, but still diverse and their bases not as yet well defined. Significant serologic and cellular experimental data support the statement that the final immunopathologic perturbation in murine (and human) SLE is a B lymphocyte hyperactivity with corresponding enhancement of serum antibodies and autoantibodies, particularly IgG, and consequent formation of pathogenic antigen–antibody ICs. On the basis of the available data, it appears that this B cell hyperactivity is polyclonal but not necessarily panclonal in nature, because not only antibodies against a wide array of autoantigens but also antibodies against incidental antigens, such as haptens, can be detected. The presence of autoantibodies and of their idiotypes in some recombinant lupus x normal murine lines expressing the normal partner's V genes, normal mice in which an exogenous or endogenous (Ipr gene) immunostimulator has been introduced, and unmanipulated normal mice indicate that lupus mice are not unique in their structural genetic Ig elements, whose presence determines the development of their autoimmune disease. The cause of B cell hyperactivity in lupus has not yet been fully elucidated. Autonomous B cell maturation does not appear likely, because B cell proliferation and differentiation in lupus mice was found to be dependent on the same number of accessory signals as in normal mice.

Organ-specific autoimmune diseases induced in mice by elimination of T cell subset. I. Evidence for the active participation of T cells in natural self-tolerance; deficit of a T cell subset as a possible cause of autoimmune disease

Abstract: Organ-specific autoimmune diseases such as oophoritis, gastritis, thyroiditis, and orchitis were induced in female or male nude (nu/nu) mice by the transfer of nu/+spleen cells from which particular Lyt T cell subset(s) had been removed: nu/+spleen cells treated with anti-Lyt-1 plus complement (C) caused disease in recipient nude mice; anti-Lyt-2 plus C-treated spleen cells, in contrast, did not. The cells responsible for disease induction are believed to be Thy-1+, Lyt-1-, 2,3- (Thy-1, Lyt-1, 2,3), since spleen cells treated with mixed antisera, including anti-Lyt-1 and anti-Lyt-2, plus C, could induce the disease with almost the same incidence as anti-Lyt-1 plus C-treated cells (oophoritis 50%, gastritis 25%, thyroiditis 10-20%, and orchitis 40%). Cells treated with mixed antisera of anti-Thy-1, anti-Lyt-1, and anti-Lyt-2, plus C, could not induce autoimmune disease. Each induced autoimmune disease could be adoptively transferred to other nude mice via spleen cells, with resulting histological lesion of corresponding organs and development of specific circulating autoantibodies. Since anti-Thy-1 plus C treatment of donor spleen cells abrogated the capacity to transfer the disease, we conclude that T cells are required as effector cells, and that these may develop from Lyt-1-, 2,3- cells. Lyt-1+, 2,3- cells were demonstrated to have suppressive activity upon the development of the diseases; induction of autoimmunity was completely inhibited by the cotransfer of Lyt-1+, 2,3- cells with Lyt-1-, 2,3- cells. When anti-Lyt-2 plus C-treated cells (i.e., Lyt-1+, 2,3- and Lyt-1-, 2,3- cells) were mixed with anti-Lyt-1 and anti-Lyt-2 plus C-treated cells (i.e., Lyt-1-, 2,3- cells) in various ratios, then transferred to nude mice, the development of each autoimmune disease was clearly inhibited, even by small doses of Lyt-1+, 2,3- cells. The autoimmune disease we were able to induce was quite similar to human organ-specific autoimmune disease in terms of the spectrum of organs involved, histopathological features, and the development of autoantibodies to corresponding organ components (oocytes, parietal cells, thyroid colloid, including thyroglobulin, and sperm).(ABSTRACT TRUNCATED AT 400 WORDS)

Retroviral induction of acute lymphoproliferative disease and profound immunosuppression in adult C57BL/6 mice.

Abstract: We have shown that a mixture of murine leukemia viruses (MuLV) causes the acute onset of lymphoproliferation and immunosuppression when injected into adult C57BL/6 mice. The ecotropic/MCF (mink cell focus-inducing) mixture of MuLV stimulates polyclonal B lymphocyte proliferation and differentiation to antibody-secreting cells. Serum Ig levels are elevated for all isotypes except IgA. The viral infection leads to a rapid decline in T lymphocyte responses to mitogens and alloantigens, as well as a decrease in helper cell activity. Specific antibody responses to both T-dependent and T-independent antigens are impaired, and the response of B lymphocytes to mitogens is abolished. The profound immunosuppression seems to be due to the MuLV-induced polyclonal activation of lymphocytes. No active suppression of normal lymphocyte responses by cells from virus-infected mice was observed. The disease induced by the LP-BM5 MuLV isolate thus seems a promising model for the study of lymphocyte activation and the mechanisms of retrovirus-induced immunosuppression.

Characterization of mixed allogeneic chimeras. Immunocompetence, in vitro reactivity, and genetic specificity of tolerance.

Abstract: Mixed allogeneically reconstituted mice (B10 + B10.D2----B10) that specifically accept B10.D2 tail skin allografts were examined for in vivo and in vitro immunocompetence, patterns of hematopoietic repopulation, and in vitro reactivity. In vitro, mixed allogeneic chimeras (B10 + B10.D2----B10) manifested specific tolerance in mixed lymphocyte reactions and cell-mediated lympholysis to B10 and B10.D2 splenocytes, with normal responses to third-party (B10.BR) cells. Such chimeras were immunocompetent in B cell and helper T cell responses, as assessed by their primary plaque forming cell responses to in vivo sheep red blood cell immunization. This is in contrast to fully allogeneic chimeras, which responded less well. In addition, survival of the mixed allogeneic chimeras in a conventional animal facility was superior to that of fully allogeneic chimeras, and similar to syngeneically reconstituted (B10----B10) mice. Specific tolerance to skin grafts, degree of allogeneic engraftment, and persistence of chimerism was also assessed in a noncongenic mixed allogeneic combination (B10 + C3H----B10). Such animals manifested specific hyporeactivity to C3H skin allografts, but eventual chronic rejection of the grafts occurred in spite of stable and persistent mixed chimerism. MHC-congenic (B10.BR) skin grafts were accepted indefinitely in the same animals, suggesting that skin-specific non-major histocompatibility complex antigens were responsible for rejection of the C3H skin allografts.

Influence of the human T-lymphotropic virus/lymphadenopathy-associated virus on functions of human lymphocytes: evidence for immunosuppressive effects and polyclonal B-cell activation by banded viral preparations

Abstract: The etiologic agent for the acquired immunodeficiency syndrome (AIDS) is now firmly established as the retrovirus termed the human T-lymphotropic virus type III (HTLV-III) or the lymphadenopathy-associated virus, LAV. The disease is characterized by profound and progressive loss of immunity, but molecular evidence indicates that only a few cells in peripheral blood are being productively infected with this virus. In the present study we have investigated a disrupted HTLV-III viral preparation for biologic effects on normal lymphoid cells. Relatively dilute concentrations of this preparation were found to stimulate immunoglobulin secretion by peripheral blood lymphocytes; at the same dosages, the preparation was inhibitory for the B-cell differentiation responses that are induced with other known polyclonal B-cell activators, pokeweed mitogen, Staphylococcus aureus, and Epstein-Barr virus. This preparation was also inhibitory at high concentrations for T-lymphocyte proliferative responses to phytomitogens and antigens and resulted in a reduced expression of Tac antigen on phytohemagglutinin-activated lymphocytes. Paradoxically, incubation of lymphocytes of certain healthy donors with the HTLV-III preparation alone resulted in increased expression of Tac and Leu-12 antigens. These findings show that a disrupted preparation of HTLV-III virus can mimic many of the immunologic abnormalities present in patients with HTLV-III infection. Nonviable viral proteins may be responsible for some of the immunologic perturbations that occur in HTLV-III-infected states.

Pregnancy outcome in human couples with recurrent spontaneous abortions: HLA antigen profiles; HLA antigen sharing; female serum MLR blocking factors; and paternal leukocyte immunization.

Abstract: Critical features of the trophoblast for immune protection in the mother are: (1) its resistance to cytotoxic lymphocytes and antibodies; (2) it forms a physical barrier to immune effector cells, but not antibody, from reaching the fetus; (3) it signals the migration of suppressor and other functionally hyporesponsive lymphocytes into the uterine decidua and uterine lymphatics; (4) it promotes the production of maternal serum MLR (mixed lymphocyte reaction) blocking antibody with paternal antigen specificity. Some of these immunological features are lacking in women with recurrent abortions of immune etiology. Eleven women who aborted an additional time after immunization with paternal leukocytes were compared with 14 women who delivered infants at term post-immunization. It was found that those who aborted: (1) had HLA antigen profiles that did not differ significantly from those of control fertile couples or from observed antigen frequencies in North American Caucasians; (2) shared more HLA A, B, D/DR, and MT antigens with their spouses than controls; (3) were not more hyporesponsive in MLR to paternal antigens pre- and post-immunization when compared to controls; (4) failed to develop female serum MLR blocking factors post-immunization; (5) failed to develop humoral alloantibodies to B-cell alloantigens; (5) had lymphocytes in the uterine decidua mantling the conceptus and in the uterine lymphatics that were reactive/cytotoxic to paternal stimulating alloantigens. These results are in sharp contrast to the immunodynamics of peripheral blood leukocytes and decidual leukocytes to paternal alloantigens in women who delivered infants at term post-immunization.

Thymic epithelium and the induction of transplantation tolerance in nude mice

Abstract: Immunological tolerance of self has been studied experimentally by the induction of unresponsiveness to antigens of the major histocompatibility complex (MHC) in neonatal mice. The specific unresponsiveness resulting from such neonatal tolerance induction is first demonstrable in the thymus, suggesting that neonatal tolerance is induced by some cellular component of the thymus, or at some prethymic stage. Recent transplantation studies suggest that thymic epithelium, derived by organ culturing fetal mouse thymus in the presence of deoxyguanosine, survives in an allogeneic host environment despite the continued expression of MHC donor antigens, but fails to induce allotolerance. We demonstrate here that embryonic thymus lobes organ cultured at 24 degrees C, a treatment that deletes the lymphohaematopoietic component of thymus leaving the epithelial matrix intact, when transplanted to intact histoincompatible recipients, similarly survive for a prolonged period and do not induce tolerance to donor MHC antigens. However, when such culture-derived thymic epithelium is allografted to athymic nude mice, host-derived lymphocytes from both the epithelial graft and recipient spleen are unresponsive to the MHC antigens of the epithelial donor. The results suggest that, when investigated in a system which precludes the possible involvement of extrinsic mature T cells, processed by the syngeneic host thymus, thymic epithelium may induce transplantation tolerance.

Acquired immunological tolerance of foreign cells is impaired by recombinant interleukin 2 or vitamin A acetate.

Abstract: The susceptibility of newborn mice to the inception of tolerance after exposure to antigen is associated with their deficiency in the production of endogenous interleukin 2 (IL-2). As further evidence of the complicity of IL-2 in the inception and maintenance of tolerance, it is shown here that a solid and long-lasting state of tolerance induced by the intravenous injection into newborn CBA mice of lymphoid cells from (CBA X C57BL/10ScSn)F1 hybrids can be brought to an end by the administration of exogenous IL-2 or by supplementing an otherwise normal diet with vitamin A acetate, the effect of which is to increase the proportion of the moiety of the T-cell population that produces IL-2. These results indicate that certain nonspecific stimuli can influence whether immunological tolerance is maintained.

Retrovirus-mediated immunosuppression. I. FeLV-UV and specific FeLV proteins alter T lymphocyte behavior by inducing hyporesponsiveness to lymphokines.

Abstract: Murine splenocytes were used to study the in vitro immunosuppressive effects of UV-inactivated feline leukemia virus (FeLV-UV). FeLV-UV blocks both alloantigen (DBA/2)-induced and Con A-induced proliferation of C57BL/6 splenocytes in a dose-dependent manner. Furthermore, C57BL/6 anti-DBA/2 mixed lymphocyte cultures containing FeLV-UV fail to develop detectable DBA/2-specific cytolytic activity, although FeLV-UV has no effect on the cytolytic activity of preformed C57BL/6 anti-DBA/2 cytolytic T cells (CTL). Disruption of lymphocyte proliferation and CTL generation by FeLV-UV could not be overcome by the addition of exogenous lymphokines. These data suggest that FeLV-UV can interfere with the lymphokine reactivity of alloactivated lymphocytes. In fact, FeLV-UV blocks the lymphokine-induced proliferation of the murine IL 2-dependent cell line CTLL-20. The CTLL-20 cells were subsequently used to study the mechanism(s) by which retroviruses alter T lymphocyte function. Normally, CTLL-20 cells undergo significant proliferation when cultured in EL4 SN, an IL 2-containing culture supernatant from PMA-stimulated EL4 cells. This lymphokine-induced CTLL-20 proliferation is abrogated in a dose-dependent manner by UV-inactivated murine leukemia virus (MuLV-UV), FeLV-UV, and a purified 15,000 dalton viral protein, p15, derived from FeLV. Suppression of CTLL-20 proliferation requires only brief contact (6 hr) with FeLV-UV or with p15, but is most efficient after prolonged (24 hr) contact with these agents. Furthermore, suppression of CTLL-20 proliferation by FeLV-UV and p15 is reversible, because CTLL-20 cells which have been pretreated for 24 hr with FeLV-UV or p15 are equally as efficient at responding to EL4 SN as untreated CTLL-20. Additional studies indicate that CTLL-20 cells continue to remove IL 2 activity from EL4 SN in the presence of suppressive concentrations of FeLV-UV, and that suppressive concentrations of FeLV-UV do not remove IL 2 activity from EL4 SN. This suggests that FeLV does not block CTLL-20 proliferation by absorbing or inactivating IL 2, or by occluding IL 2 receptors, and that T lymphocytes develop an insensitivity to lymphokines after contact with FeLV-UV, which may be caused by a metabolic, rather than an immunologic, defect. Because lymphokines are requisite signals for T cell function, considerable immunosuppression would be associated with acquired lymphokine insensitivity.

Mechanisms maintaining enhancement of allografts. I. Demonstration of a specific suppressor cell.

Abstract: DA rats treated with hyperimmune anti-PVG serum and grafted with (DA X PVG)F1 heart grafts in which graft survival was prolonged for greater than 75 d were used to examine the cellular mechanisms that maintain the state of specific unresponsiveness found in these animals. The capacity of lymphocytes from these animals to effect or inhibit graft rejection on adoptive transfer to irradiated heart-grafted hosts was tested. Spleen cell populations and the T cell subpopulation separated from spleen cells in vitro failed to restore rejection of PVG heart grafts in irradiated DA recipients but restored third party Lew graft rejection. Whole spleen cells had the capacity to suppress the ability of normal DA LNC to cause graft rejection, but T cells from spleen only delayed the restoration of rejection. LNC and recirculating T cells from rats with enhanced grafts adoptively restored PVG rejection, however. These studies show that the state of specific unresponsiveness that follows the induction of passive enhancement is dependent in part upon active suppression, which is induced or mediated by T lymphocytes. The recirculating pool of lymphocytes in these animals is not depleted of specific alloreactive cells with the capacity to initiate and effect rejection. Thus, these animals' unresponsiveness is not like that found in transplantation tolerance induced in neonatal rats, but is, in part, due to a suppressor response that can inhibit normal alloreactive cells' capacity to initiate and effect rejection.

Down-regulation of immune responses to inhaled antigen: studies on the mechanism of induced suppression.

Abstract: Repeated exposure of rats to an aerosol of ovalbumin (OVA) or its dinitrophenylated derivative (DNP-OVA) induced carrier-specific tolerance to subsequent challenge with the same haptenated antigen. Following parenteral challenge with DNP-OVA, both anti-DNP and anti-OVA IgE titres were reduced relative to controls, whereas anti-DNP responses following challenge with DNP-Ascaris were normal. Stimulation of tolerant rats with OVA, together with the polyclonal B-cell mitogen LPS, restored their capacity to respond to the antigen. In contrast to WAG rats, which have previously been shown to develop equivalent tolerance in the IgE an IgG antibody classes (Sedgwick & Holt, 1984), BN rats exposed to an OVA aerosol developed high serum titres of anti-OVA IgG. Following parenteral challenge with DNP-OVA, however, anti-DNP IgG responses in the BNs were markedly reduced relative to unexposed controls, while anti-OVA IgG titres were maintained at a high level. Further strain-dependent differences in T-cell function in tolerized rats appeared in in vivo assays of DTH reactivity and in in vitro antigen-driven lymphocyte proliferation. Both BN and WAG rats displayed diminished in vitro responses, whereas DTH reactions were only suppressed in the latter strain.

Induction and control of the gastrointestinal immune system.

Abstract: The stimulation of cells in gut associated lymphoid tissue (GALT) by intestinal antigens can result either in immunity or tolerance to that antigen. The factors that determine which effect predominates are not understood, but the answer seems to lie in a better understanding of the cellular interactions and regulatory mechanisms in GALT. Induction of an immune response in GALT involves the same macrophage-T cell, T cell-T cell, and T cell-B cell interactions that have been described in other lymphoid tissues. Regulatory T cells have now been shown to play an important role in controlling the immune response to intestinal antigens. The presence of helper T cells specific for the IgA isotype in Peyer's patches may partly explain the old observation that the intestinal route is preferential for this antibody class. The stimulation of suppressor T cells in GALT is responsible for many instances in which tolerance rather than immunisation has followed antigen feeding. Although there is experimental evidence supporting the idea that mucosal IgA immunity and systemic IgG tolerance can occur concomitantly after antigen feeding, recent data obtained after the feeding of a variety of protein antigens indicate that this is not the usual result. More commonly either immunity or tolerance occurs concomitantly in both mucosal and systemic systems after antigen feeding, suggesting that the suppressor cells mediating oral tolerance also suppress mucosal IgA responses.

T cell tolerance studied at the level of antigenic determinants. I. Latent reactivity to lysozyme peptides that lack suppressogenic epitopes can be revealed in lysozyme-tolerant mice.

Abstract: Whether T cell tolerance represents direct inactivation of antigen-specific T cells via recognition of antigen plus major histocompatibility complex, or via T suppressor (Ts) cells, or a combination of these mechanisms, remains to be clarified. This problem was investigated using a novel approach based on the finding in several systems that T helper/proliferative (Th/Tp) cell-inducing antigenic determinants are dissociable from Ts cell-inducing determinants. Thus, peptide probes containing known sites that stimulate T proliferative activity, as well as peptides from distinct sites assumed to bear Ts-inducing determinants, were used in studying hen (chicken) eggwhite lysozyme (HEL)-tolerant mice. The clear prediction from clonal deletion model is that Th/Tp response potential to short peptides in the tolerant mouse would not exist, while regulatory suppression models predict the coexistence of antigen-reactive cells and antigen-specific regulatory cells that prevent their expression. Adult mice, treated with 2 mg HEL in saline, were tolerant to HEL in complete Freund's adjuvant (CFA). Latent T cell proliferative responses could be revealed to determinants within two HEL peptide probes, which lacked the amino-terminal region of the molecule. This responsiveness suggested two conclusions: first, Ts cells directed against the amino terminus of lysozyme exist in the tolerant genetic responder B10.A; second, these Ts regulate the activity of functional antigen-reactive T cells directed against epitopes elsewhere on the molecule, but only in the presence of the complete molecule, HEL. Examination of neonatally induced tolerance did not reveal any latent responsiveness, supporting the hypothesis that clonal deletion or anergy is the relevant mechanism in this situation. Possible reservations in these explanations of the two tolerant states, plus analysis of the more complex "split tolerance" resulting from 20 mg HEL in saline treatment in adults, are discussed. The approach of dissociation of proliferation-inducing determinants from suppression-inducing determinants clarifies our understanding of the tolerant state and holds promise for more definitive exploration of mechanisms of T cell tolerance.

The microenvironment of coeliac disease: T cell phenotypes and expression of the T2 'T blast' antigen by small bowel lymphocytes.

Abstract: Peroral jejunal biopsies were studied by double-label immunofluorescence on cryostat tissue sections from control patients of normal histology and patients with coeliac disease. A panel of monoclonal antibodies was used to identify T cells and T cell subsets, together with antibody markers of cell stimulation (the T2 40 kdalton T blast specificity), proliferation (T9 and Ki67) and activation (HLA-DR and Ig receptors). In normal mucosa, expression of T2 was predominantly found in the T8+ intraepithelial cytotoxic/suppressor population. In coeliac disease there was little alteration of T4:T8 ratios per se, but a much higher percentage of T8-T4+ helper/inducer cells expressed the T2 antigen (approx. 30% compared to approx. 10%), manifest as an accretion of T2+T8- cells in the epithelium and subjacent stroma. Additionally, T cell lymphoid aggregates were observed in the lamina propria, consisting of greater than 90% T4+ cells, of which the majority (60-80%) were also T2+. The increase of stimulated helper cells correlated well with the pathology of coeliac disease, being most marked in untreated cases of maximal tissue damage, and least in well treated cases with restoration of normal morphology. By contrast, an increased tendency for the T8+ cells to co-express T1 in untreated coeliac disease was not observed in treated disease, even in cases where failure to adhere to a strict gluten free diet had resulted in little histological improvement. There was little evidence of T cell activation or proliferation. The observation that T helper cells undergo migration and stimulation suggests an imbalance in immunoregulation which causes a breakdown of normal immune tolerance to dietary gluten, and therefore may be a crucial mechanism of tissue damage in coeliac disease.

Undiminished immunologic tolerance to contact sensitivity in mast cell-deficient W/Wv and Sl/Sld mice.

Abstract: Several mast cell-derived mediators, when tested individually, have actions that may be considered immunosuppressive or anti-inflammatory. Yet evidence concerning the importance of mast cells to the down regulation of T cell-dependent immune responses in vivo is scanty and contradictory. To test directly the net contribution of intact mast cells to the suppression of delayed hypersensitivity reactions in vivo, we attempted to elicit tolerance to contact sensitivity in W/Wv or Sl/Sld mast cell-deficient mice, and compared their responses with those of littermate control mice with normal numbers of mast cells. By using three different measures of delayed hypersensitivity (ear swelling, weight ratios of challenged and control ears, and 125I-IUDR-labeled leukocyte infiltration into challenged and control ears), we detected no deficiency in the 24 hr contact sensitivity reactions to DNFB in control (nontolerized) W/Wv or Sl/Sld mice. We thus confirmed previous work indicating that mast cells are not essential for the induction and elicitation of delayed hypersensitivity. Furthermore, mast cell-deficient and control mice developed equivalent levels of tolerance to contact sensitivity. This was true for tolerance induced by DNBS administered i.v. 7 days before epicutaneous sensitization with DNFB, and for tolerance induced by supraoptimal sensitization with DNFB. W/Wv and Sl/Sld mice also served as suitable donors and recipients for putative suppressor T cells (Ts) induced by i.v. DNBS. We conclude that mast cells make little or no contribution to the modulation of Ts activity in two different models of Ts-dependent tolerance to contact sensitivity.

The role of antigen recognition and suppressor cells in mice with oral tolerance to ovalbumin.

Abstract: The induction of tolerance by feeding proteins may prevent potentially harmful delayed-type hypersensitivity (DTH) reactions to food antigens Suppressor T cells (Ts) are present in mice with tolerance of systemic DTH after feeding ovalbumin (OVA) but, as other immunoregulatory mechanisms have also been described, the exact role of Ts in maintaining tolerance is not known In this study, we have used the ability of native and denaturated OVA to cross-react at the level of helper/effector T cells, but not Ts, to re-examine the role of Ts in oral tolerance to OVA Mice immunized with native OVA (nOVA) or denatured OVA (dOVA) in adjuvant had fully cross-reacting DTH to either nOVA or dOVA, but intravenous administration of antigen induced Ts which were specific for the appropriate form Mice fed nOVA or dOVA had identical tolerance of systemic DTH to both forms of OVA, and feeding nOVA induced splenic Ts which suppressed the DTH response to both nOVA and dOVA Splenic Ts could not be detected in mice fed dOVA The results support the hypothesis that tolerance of systemic DTH in mice fed native proteins is due to Ts Although, for the moment, there is no complementary evidence for a role for Ts in oral tolerance to denatured proteins, this study is consistent with the idea that Ts are the mechanism which normally prevent enteropathy due to DTH against dietary proteins In addition, our study underlines the differences between orally and parenterally induced Ts and reinforces the view that fed proteins induce Ts after processing by the gut or its lymphoid accessory cells

Sera from patients with the acquired immunodeficiency syndrome inhibit production of interleukin-2 by normal lymphocytes.

Abstract: We studied the effects of sera from patients with the acquired immunodeficiency syndrome (AIDS) on interleukin-2 (IL-2) production to help elucidate the mechanism of immunodeficiency. Compared with sera from healthy controls, sera from AIDS patients suppressed phytohemagglutinin (PHA)-induced IL-2 production by normal blood mononuclear cells. Sera from homosexual contacts of AIDS patients and from adults with acute cytomegalovirus infection generally lacked this suppressive activity. The effect of the AIDS sera could not be attributed to absence of a stimulatory or nutritive factor, to inactivation of IL-2, to inhibition of the IL-2 assay, nor to increased turnover of IL-2. The suppressive effect of the sera was not mediated by radiosensitive or T8 antigen-bearing suppressor cells or by increased prostaglandin production or decreased interleukin-1 production. The sera acted directly on the groups of cells that produce IL-2, T cells and large granular lymphocytes; suppression occurred at an early, probably pretranslational, stage. When cells were incubated with AIDS sera and then washed, the suppressive effect persisted. The sera did not cause direct or complement-mediated cytotoxic effects on normal mononuclear cells nor did they suppress PHA-induced interferon production, nor proliferation of T lymphoblasts or lymphocyte lines. The suppressive effect was not mediated by interferon, cortisol, immunoglobulin G or M, or immune complexes. The activity was stable at pH 3, pH 10, and 60 degrees C; inactivated at 100 degrees C; and not ether extractable. Because IL-2 plays a central role in the development of many immune responses, the serum factor(s) that inhibits IL-2 production could contribute significantly to the immunodeficiency of AIDS.

Adoptive transfer of suppression of arthritis in the mouse model of collagen-induced arthritis. Evidence for a type II collagen-specific suppressor T cell.

Abstract: This study details the suppressive mechanism involved in the antigen-specific suppression of collagen-induced arthritis. Intravenous injection of 500 micrograms of soluble native type II collagen 3 d before immunization with native type II collagen emulsified in complete Freund's adjuvant resulted in animals with decreased in vitro cellular and humoral immune response to native and denatured type II collagen compared with control groups. Control groups were composed of animals preinoculated with saline and type I collagen and established the antigen-specific nature of the observed suppression. Mice with reduced immune responses to type II collagen also were observed to portray little or no erythema and edema associated with collagen-induced arthritis. Adoptive transfer experiments established the requirement of T cells for the suppression of collagen-induced arthritis. Analysis of the phenotype of responding splenic cells in chronic immunotherapeutically suppressed mice in vitro revealed that responding cells were Ly1-2+ (suppressor/cytotoxic) T cells. On the other hand, the cellular phenotype of T cells responding to type II collagen in nonsuppressed collagen-induced arthritic mice was Ly1+2- (helper/inducer T cells). The data indicate that type II collagen-specific T cells are generated on intravenous inoculation of soluble native type II collagen. These cells are observed in type II collagen-immune animals, which are nonarthritic and portray reduced humoral and in vitro cellular immune response to type II collagen. This study suggests that specific suppression of immune responses to type II collagen by T-suppressor cells can be immunotherapeutic in certain forms of arthritis.

Characterization of antigen-specific, Ia-restricted, L3T4+ cytolytic T lymphocytes and assessment of thymic influence on their self specificity.

Abstract: The goals of the present study were: (a) to generate antigen-specific L3T4+ cytolytic T lymphocytes (CTL), (b) to determine their major histocompatibility complex (MHC) restriction specificity, and (c) to assess the influence of thymic MHC determinants on their self specificity. We found that L3T4+ CTL specific for either trinitrophenyl (TNP)-modified self determinants or minor histocompatibility antigens could be generated from Lyt-2- responder T cells provided that the response cultures were supplemented with supernatants rich in helper factors. Such antigen-specific L3T4+ CTL were Ia-restricted by the criteria that they lysed only Ia+ target cells and that their lysis of Ia+ target cells was specifically inhibited by anti-Ia monoclonal antibodies. The relative frequency of L3T4+ pCTL was found to be only 5-10% of the total anti-TNP pCTL present in the spleens of normal mice. Finally, we utilized radiation bone marrow chimeras to assess the influence of the thymic haplotype on the self-Ia specificity of L3T4+ CTL. Both bulk culture and limiting dilution experiments revealed that the self-Ia specificity of L3T4+ anti-TNP CTL from F1\---|-parent and A\---|-B allogeneic chimeras was not markedly skewed toward the haplotype of the chimeric thymus. These results contrast with those obtained previously for L3T4+ anti-TNP Th cells and demonstrate that in the radiation bone marrow chimera model of T cell differentiation, the self specificity of Th cells but not pCTL is markedly influenced by the haplotype of the chimeric thymus.

Failure of OKT3 monoclonal antibody to induce lymphocyte mitogenesis: a familial defect in monocyte helper function.

Abstract: Monoclonal antibodies to the T3 molecule on human T cells have mitogenic activity. Although anti-T3 antibodies of the IgG1 subclass (e.g., UCHT1) induce mitogenesis in lymphocyte cultures from only 60 to 70% of normal donors, antibodies of Ig2a subclass (e.g., OKT3) invariably have been found to be mitogenic in all subjects tested up to the present. This paper describes a family (a mother, six daughters, and one son) in which five members failed to respond mitogenically to OKT3 although the proportion of OKT3-reactive cells in their peripheral blood was normal. Mitogenic responses to PHA, Con A, and PWM were normal. Five members comprising four OKT3 nonresponders were also unresponsive to UCHT1. Unresponsiveness to OKT3 and unresponsiveness to UCHT1 were not absolutely linked to each other, nor were they linked to an HLA haplotype inherited from the mother. Upon stimulation by OKT3, lymphocyte preparations from OKT3-nonresponders failed to produce interleukin 2 (IL 2) and to display IL 2 receptors. OKT3 unresponsiveness was due to defective monocyte help: thus, responsiveness to OKT3 of T cells from an OKT3-nonresponder was restored by the addition of monocytes from an HLA-identical sister who had a normal response to OKT3. Inversely, T cells from the OKT3 responder had no reactivity to OKT3 when cultured in the presence of monocytes from an HLA-identical, OKT3-nonresponsive sister. Unresponsiveness to OKT3 could not be overcome by the addition of phorbol myristate acetate to the cultures. These data on a familial, non-HLA-linked deficiency of monocytes to exert their auxiliary function provide better insight into the mechanism of anti-T3-induced T cell activation.

Functional clonal deletion versus active suppression in transplantation tolerance induced by total-lymphoid irradiation.

Abstract: Transplantation tolerance and stable chimerism were established in adult mice conditioned with a short course of total-lymphoid irradiation (TLI) followed by infusion of 30 X 10(6) allogeneic bone marrow cells. Spleen cells of tolerant mice could not exert a proliferative or cytotoxic response against host-type cells in vitro and were unable to induce graft-versus-host reaction in secondary host-type recipients. The degree of suppression assessed by coculturing tolerant splenocytes in vitro in the one-way mixed lymphocyte reaction was quite variable--and, in some cases, was not at all demonstrable, although tolerance was clearly maintained. Suppression, when apparent, could not be ascribed to T lymphocytes. Suppressor cells were found to bind soybean agglutinin and could be separated from the nonsuppressive cells by means of this lectin. Dissociation of the suppressive population (SBA+ cells) from that which is normally alloreactive (SBA- cells) resulted in a suppressor cell-depleted fraction that was still unable to respond to host-type cells but regained reactivity to unrelated cells. Limiting dilution analysis of chimeric splenocytes revealed markedly reduced frequencies of cytotoxic T lymphocyte precursors (CTL-P) directed against host-type cells, as compared with normal splenocytes reacting against the same target cells. This difference was accentuated when these cells were sensitized tomore » host-type target cells prior to plating in limiting dilution cultures. In 1:1 mixing experiments of normal and chimeric splenocytes, there was no evidence of any in vitro suppressive activity to account for hyporeactivity of chimeric cells against host-type cells. Thus, maintenance of TLI-induced tolerance seemed not to be mediated primarily through an active suppressor cell mechanism.« less

Correlation of intrathymic tolerance with intrathymic chimerism in neonatally tolerized mice

Abstract: T cell tolerance to alloantigens can be induced in neonatal mice by the injection of semiallogeneic adult spleen cells. The thymus of neonatally injected mice rapidly becomes specifically unresponsive to the alloantigens expressed by the injected cells, even though the level of chimerism in the thymus of such mice is reportedly marginal compared with that of the periphery. In this report, we have studied the immune reactivity and degree of chimerism in the thymuses of 24 neonatally injected mice. In 13 older mice, the proliferative response of the thymocytes from individual mice to the injected alloantigen varied from strong reactivity to complete tolerance. Interestingly, analysis by flow microfluorometry of the same thymocytes for the presence of the inoculated alloantigen revealed an inverse correlation. That is, the thymuses which had a greater degree of chimerism were tolerant and those with fewer or no detectable cells were partially or totally reactive. The thymuses of 11 younger neonatally injected mice were invariably tolerant to both the MHC and Mls alloantigens of the F1 inocula. Analysis by flow microfluorometry of the thymocytes of these mice revealed that significant numbers of F1 cells reside in the thymuses of mice injected as neonates with semiallogeneic cells. These cells represent a possible source of specific tolerogen for thymocytes during their intrathymic differentiation.

Strain variation of bacillus Calmette-Guerin-induced pulmonary granuloma formation is correlated with anergy and the local production of migration inhibition factor and interleukin 1.

Abstract: Pulmonary granulomatous inflammation was induced by the intratracheal injection of viable bacillus Calmette-Guerin (BCG) into genetically high granuloma responder (C57BL/6J and BALB/c) and low responder (CBA/J) mice with and without immunization by methylated bovine serum albumin in complete Freund's adjuvant. Significant migration inhibition factor (MIF) and interleukin 1 (IL 1) activities were detected in aqueous lung granuloma extracts prepared from high responder mice bearing BCG-induced granulomatous inflammation. Interleukin 2 activity was not detected. Very low MIF and IL 1 activities were detected in extracts from low responder mice. Furthermore, high responder, but not low responder, mice showed marked suppression of in vivo and in vitro manifestations of cell-mediated immunity to both specific and nonspecific antigens. In contrast, humoral antibody response was not affected significantly. The kinetics of anergy in granuloma-bearing mice correlated closely with the appearance of MIF and IL 1 activities in the lesions. Thus, genetically determined granuloma response to BCG and the expression of anergy in various strains of mice were well associated with in vivo release of MIF and IL 1. These results indicate that the genetic ability or inability to mount a granulomatous inflammatory response to BCG may extend to the capacity of cells within the lesions to generate soluble mediator(s) which is also responsible for anergy in granuloma-bearing mice.

Tolerance to parenchymal self. Regulatory role of major histocompatibility complex-restricted, OX8+ suppressor T cells specific for autologous renal tubular antigen in experimental interstitial nephritis.

Abstract: BN rats develop interstitial nephritis after immunization with rabbit, but not rat renal tubular antigen. Using RT1n rat strains that differentially express tubular antigen, we investigated the unresponsiveness of BN rats to BN tubular antigen (BN-TBM) using delayed-type hypersensitivity (DTH) responses to BN-TBM as a measure of cell-mediated immunity. Our results indicate that rat strains expressing tubular antigen respond to immunization with BN-TBM with the clonal expansion of antigen-specific, cyclophosphamide-sensitive, OX8+, MHC-restricted suppressor T cells. Such suppression appears to be relevant to the maintenance of tolerance to parenchymal self, since chronic cyclophosphamide therapy abrogates suppression and results in significant interstitial nephritis.