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

Suppressor cells and their precursors in A/J mice, tolerant to heterologous gamma globulin

The role of suppressor cells and of their precursors was examined in A/J mice, immunized or tolerized-immunized with rabbit gamma globulin. Antibody response and tolerance were assessed by antigen elimination, followed by an indirect plaque-forming assay. Reconstitution experiments were performed to estimate loss of cooperative capacity in thymus and spleen cells. Infectious tolerance was examined by reconstitution with mixtures of spleen or thymus cells of normal and tolerant donors. Infectious tolerance could not be detected after neonatally induced tolerance. It could be detected when tolerance was induced 11-16 days after birth. Under these circumstances, loss of cooperative capacity and increased capacity for infectious tolerance occurred rapidly over the first 2 days and reached completion by the 10th-20th day after administration of tolerogen. Thymectomy, after tolerance induction, resulted in relative recovery of responsiveness of spleen cells and loss of capacity for infectious tolerance. Pretreatment with cyclophosphamide resulted in a less profound state of unresponsiveness and in the disappearance of the capacity for infectious tolerance. Simultaneous treatment with tolerogen and colchicine also resulted in a less profound state of tolerance. This effect of colchicine was more profound when a low dose of tolerogen was used or when animals were thymectomized before administration of tolerogen and colchicine.

Glutathione levels in antigen-presenting cells modulate Th1 versus Th2 response patterns

Current thinking attributes the balance between T helper 1 (Th1) and Th2 cytokine response patterns in immune responses to the nature of the antigen, the genetic composition of the host, and the cytokines involved in the early interaction between T cells and antigen-presenting cells. Here we introduce glutathione, a tripeptide that regulates intracellular redox and other aspects of cell physiology, as a key regulatory element in this process. By using three different methods to deplete glutathione from T cell receptor transgenic and conventional mice and studying in vivo and/or in vitro responses to three distinct antigens, we show that glutathione levels in antigen-presenting cells determine whether Th1 or Th2 response patterns predominate. These findings present new insights into immune response alterations in HIV and other diseases. Further, they potentially offer an explanation for the well known differences in immune responses in "Th1" and "Th2" mouse strains.

Regulation of the effector stages of experimental autoimmune encephalomyelitis via neuroantigen-specific tolerance induction. III. A role for anergy/deletion

Our previous work has shown that specific peripheral immune tolerance induced by the intravenous administration of ECDI-fixed, antigen-coupled syngeneic splenocytes is an extremely efficient method for prevention and treatment of chronic relapsing experimental autoimmune encephalomyelitis (R-EAE) in susceptible SJL/J mice. The current study examined the mechanisms by which unresponsiveness is induced in primed encephalitogenic T cells. The results indicate that the inhibition of MBP-specific T cells by the i.v. injection of MBP-coupled splenocytes is not due to the induction of antigen-specific regulatory T cells, but rather to the induction of anergy/deletion of the effector cells. This conclusion is supported by the findings that spleen or lymph node cells isolated from MBP-tolerant mice fail to inhibit the adoptive transfer of R-EAE in cotransfer assays, and that tolerance is not inhibited by prior thymectomy or prior treatment with cyclophosphamide or anti-CD8 monoclonal antibody. In contrast, we demonstrate that splenocytes from MBP-tolerized, asymptomatic mice have a significantly reduced ability to serially transfer R-EAE to naive secondary recipients following antigen re-activation in vitro, in the first several weeks following tolerization, but that the ability to serially transfer R-EAE returns to sham tolerant control levels within 1-2 months. We also demonstrate a significantly reduced precursor frequency of MBP-specific, IL-2-producing T cells in the MBP-tolerant within three days of treatment. Collectively, the data most closely support a model wherein inhibition of MBP-specific encephalitogenic CD4+ effector T cells by i.v. injected MBP-coupled splenocytes is due to the direct induction of anergy/deletion from which they can recover over time.

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.

Antigen-specific tolerance as a therapy for experimental autoimmune encephalomyelitis

The effects of neuroantigen-specific tolerance on the induction and effector stages of EAE were examined. Tolerance induced by the i.v. injection of syngeneic splenocytes coupled with purified neuroantigens or encephalitogenic peptides of MBP and PLP using ethylene carbodiimide was extremely effective in both prevention and treatment of acute and relapsing forms of EAE in Lewis rats and SJL/J mice. The unresponsiveness is rapidly-induced, dose-dependent, long-lasting, efficient, MHC class II-restricted, and exquisitely antigen-specific. This procedure targets only effector cells bearing clonotypic receptors specific for the autoantigen/autoepitope and thus does not depend upon the autoimmune response being dominated by a restricted T cell repertoire. Moreover, it does not require that the response to the autoantigen be dominated by recognition of a specific epitope(s) within a particular autoantigen, or even the identification of the specific autoantigen. The results also demonstrate the usefulness of peripheral tolerance induced by antigen-coupled syngeneic splenocytes for identifying the fine specificity of autoimmune T cell responses which appear to change during the progression of relapsing EAE. Thus, this technique offers major advantages over many other currently employed immunoregulatory strategies and is therefore relevant for establishment of therapeutic protocols for the antigen-specific treatment of human T cell-dependent autoimmune disorders.

Reconstitution of cytolytic alloreactivity with N-[4-[(4-fluorophenyl) sulfonyl]phenyl]acetamide (CL 259,763) in animals immunocompromised by cyclophosphamide

A novel synthetic immunopotentiator, i.e. N-[4-[(4-fluorophenyl)sulfonyl]phenyl]acetamide (CL 259,763), was investigated for its potential in reconstituting the cell-mediated immune response of animals whose immunologic system had been severely depressed by cytoreductive agents. It was demonstrated that lymphocytes from mice which had received 300 mg/kg of cyclophosphamide (CY) immediately following antigen sensitization had a reduced capability of responding to alloantigens in mixed lymphocyte culture and failed to generate effective cytolytic T-lymphocytes (CTL) capable of destroying appropriate tumor target cells in a cytotoxicity assay. However, treatment of these immunocompromised animals with CL 259,763 produced a significant restoration of alloreactivity, as evidenced by an enhancement of the CTL response. Although effective doses of CL 259,763 ranged from 20 to 300 mg/kg, the optimal effect was observed at 75 mg/kg. Findings from a time course study indicated that the maximum restoration occurred when CL 259,763 was given to mice 2-5 days after, but not before or simultaneously with, CY treatment. Both the immunoimpairment by CY and its reversal by CL 259,763 appeared not to be antigen specific. The lessened immunoreactivity of CY-treated mice was explicable by the presence of suppressor cells in their spleens. These suppressors were able to adhere to plastic and resisted treatment with anti-Thy 1.2 antibody, indicating a macrophage characteristic. Flow cytometric analysis indicated a quantitative depletion of all T-lymphocytes, including Thy-1.2(+), Lyt-1(+), Lyt-2(+) and L3T4(+) subsets in the spleens of CY-treated mice; however, a population of Mac-1(+) cells was markedly expanded.(ABSTRACT TRUNCATED AT 250 WORDS)

Cyclosporin A enhances the pulmonary granuloma response induced by Schistosoma mansoni eggs

The modulating effect of cyclosporin A (CsA) was studied in the immune-based pulmonary granuloma response to Schistosoma mansoni eggs. The extent of the S. mansoni egg-induced inflammation was quantitated biochemically by measuring total units of N-acetyl-beta-D-glucosaminidase (NAG) and total lung DNA. The enzyme NAG was used as a marker for the activity of inflammatory cells such as macrophages and DNA levels were used to quantify the increased cellularity of the lungs. In this model, the inflammatory response is maximal approximately 2 weeks after egg injection. Daily oral administration of CsA at 50 mg/kg during the first 2 weeks of the response dramatically enhanced the levels of pulmonary inflammation. Similar augmentation of the granuloma response was seen when CsA was given from days 0 to 7 but not when dosed from days 8 to 14. The enhancing of CsA was seen in the high-responder strains C57BL/10, B10.BR and CBA and in a lower-responder strain, Balb/c. Both the S. mansoni egg-induced granuloma response and the CsA-induced enhancement were dependent on functional T cells: athymic C57BL/6 nude (nu/nu) mice developed minimal responses to S. mansoni eggs which CsA did not augment, while heterozygous (nu/+) euthymic B6 mice responded to S. mansoni eggs and CsA. It appears in this model system that CsA may inhibit the activity of suppressor inducer or suppressor T cells. Cyclophosphamide, a drug known to reduce suppressor cell function, augmented the egg-induced inflammatory response similar to CsA. The enhancing activities of CsA and cyclophosphamide were not additive, suggesting effects on a common pathway of biologic activity, the generation of suppressor cells. While CsA and cyclophosphamide augmented the inflammatory process, conventional immunosuppressive drug therapies, dexamethasone and BW755c, quantifiably reduced the levels of NAG and DNA. These results demonstrate that CsA, rather than being immunosuppressive, augments this immune-based model of inflammation. In addition, this study shows that pulmonary granulomatous inflammation can be quantified biochemically with assays for both NAG and DNA.

Mechanisms of genetic control of immune responses. II. Nonresponsiveness in BALB/c GT-specific cell-mediated immune responses does not correlate with the absence of functional T cells or the induction of suppressor T cells

The mechanisms underlying Ir gene control of CMI were addressed by examining the DTH and Tprlf responses specific for the synthetic polymers GT, GAT, and GA. We show that BALB/c mice (GAT/GA responders, GT nonresponders) primed with GT fail to develop DTH and Tprlf responses specific for GT, GAT, or GA. GAT immunization resulted in DTH responses that could be elicited not only with GAT and GA but also with GT, demonstrating that GT-specific TDH are present in nonresponder mice. GT-specific DTH was transferred with Thy-1+ Lyt-1+2-, H-2 I-restricted, nylon wool nonadherent cells. GA-primed BALB/c mice developed GAT- and GA-, but not GT-specific DTH responses, indicating that GA and GT do not cross-react at the T-cell level. The ability of GAT [but not a mixture of GA plus GT, or GT electrostatically complexed to the immunogenic carrier MBSA (GT-MBSA)] to induce GT-specific DTH suggested a requirement for covalent linkage of stimulatory 'GA' and nonstimulatory 'GT' determinants present on the GAT molecule. Similarly, GT-specific in vitro Tprlf responses could be demonstrated in GAT-primed mice exhibiting significant levels of GT-specific DTH but not in GT- or GT-MBSA-primed mice. Tolerization experiments also suggested that GT-specific Th were involved in the development of GT-specific DTH in GAT-primed mice. The GT nonresponsiveness of BALB/c mice for DTH and Tprlf responses could not be reversed by treatments designed to abrogate Ts activity (priming with GT-MBSA and CY injection), nor could GT-primed cells be shown to inhibit the development or elicitation of GT-specific CMI in GAT-primed mice during the afferent and/or efferent stages of DTH. Our results suggest that GT nonresponsiveness does not result from the absence of GT-specific T cells or preferential induction of Ts. The results are discussed in the context of hole-in-the-repertoire and antigen presentation (determinant selection) models of Ir gene control.

Features of KLH-induced suppression in vivo: characterization of two pathways of suppression

Keyhole limpet hemocyanin (KLH) given at high dose (4 mg ip) in mice induced a state of unresponsiveness related to the activation of suppressor T cells. An early pathway of suppression is observed within the first 24 hr following KLH injection and is characterized by its cyclophosphamide (CPM) sensitivity and by the specificity of its effector phase, at the level of KLH helper T cells. A late pathway of suppression occurs at Day 3 following KLH injection and is characterized by its CPM resistance and the nonspecificity of its effector phase acting at the B-cell level. Indeed the anti-FLu antibody response to FLu Ovalbumin or thymus-independent antigen FLu LPS were found altered when these antigens were given with TNP KLH. These two pathways of suppression were found to last 8 months. These results suggest that KLH can trigger in an independent manner two pathways of suppression characterized by different CPM sensitivity and different target cells.

Immune response to the p-azobenzenearsonate-L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT) conjugate. III. Mechanisms of Ir gene-controlled phenotype conversion

Immunization of GT (random copolymer of L-glutamic acid51-L-tyrosine49) nonresponder animals with p-azobenzenearsonate (ABA) GT conjugates elicits an antibody response to both ABA and GT epitopes which is induced by ABA-specific T helper cells. Expression of these hapten-specific helpers is under the control of an I region gene which also regulates the proliferative T cell response to ABA. Conversion of the unresponsive phenotype to GT is, therefore, dependent on the ABA Ir gene and escapes the influence of the GT-specific I region-controlled suppressive pathway. Studies on the influence of ABA/polymer coupling ratio on T and B cell responses suggest that ABA-specific T cells, like conventional carrier-specific helpers, require linked interactions with B lymphocytes to provide helper signals. GAT (terpolymer of L-glutamic acid60-L-alanine30-L-tyrosine10) nonresponder animals immunized with ABA-GAT conjugates also develop an antibody response to ABA which is induced by ABA-specific T helper cells. Comparison of antibody affinity, specificity, isotypes and idiotypes in different mouse strains demonstrates that hapten-specific helper cells stimulate antibody responses to ABA which are qualitatively similar to those induced by GAT-specific helpers. However, ABA-specific helper cells do not permit the conversion of the I region gene-controlled nonresponder phenotype to GAT. The data suggests that high ABA density, which is required for optimal ABA help expression, extinguishes the immunogenicity of GAT determinants at both T and B cell levels.

Modulation of bleomycin-induced pulmonary fibrosis in the BALB/c mouse by cyclophosphamide-sensitive T cells

Endotracheal bleomycin treatment is an effective inducer of pneumonitis and pulmonary fibrosis. Certain strains of mice, however, develop only minimal or no pulmonary fibrosis after treatment with bleomycin. The mechanism of unresponsiveness or low responsiveness in the BALB/c strain of mice is examined in this article. Pretreatment with cyclophosphamide (100 mg/kg) 2 days prior to bleomycin instillation significantly augmented the fibrotic response in these mice. Treatment by cyclophosphamide alone at the same dosage caused no significant pulmonary disease or fibrosis. Furthermore, suppression of fibrosis in the cyclophosphamide-pretreated animals could be reconstituted with spleen cells from normal untreated donor mice. If the donor spleen cells were depleted of T cells by cytotoxic anti-Thy-1.2 antisera prior to infusion into recipient animals, no such reconstitution was observed, suggesting that a population of splenic T cells was responsible for the effect. Since this dose of cyclophosphamide is known to be cytotoxic for suppressor T cells, these data would signify that the intensity of the lung fibrogenic response to bleomycin in BALB/c mice can be modulated by a population of this T cell subset. Furthermore, the cell reconstitution data would exclude the possibility that cyclophosphamide augments the bleomycin response by non-T-cell-mediated synergistic effects on lung injury. Nevertheless, the results conclusively demonstrate the ability of T cells to modulate pulmonary fibrosis in vivo, at least in the BALB/c mouse.

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.

Immunoregulatory pathways in adult responder mice. I. Induction of GAT-specific tolerance and suppressor T cells for cellular and humoral responses

This report describes the alteration of helper-suppressor balances in an immune response (Ir) gene-controlled system by varying the route and form of antigen injection. Adult responder BALB/c mice develop Lyt 1+2-, T cells for delayed-type hypersensitivity (DTH), and T-cell proliferative (Tprlf) responses to subcutaneous injection of either poly(Glu60Ala30Tyr10) (GAT)-coupled syngeneic spleen cells (GAT-SP) or GAT emulsified in complete Freund's adjuvant. In contrast, intravenous injection of adult responders with GAT-SP results in specific unresponsiveness for DTH, Tprlf, interleukin-2, and plaque-forming cell (PFC) responses. This tolerance is mediated by both suppressor T cells (Ts) and a functional clonal inhibition. Lyt 1-2+ Ts suppress the induction (afferent limb) of GAT-specific DTH and PFC but not Tprlf responses. The reduced T-cell proliferation observed in GAT-tolerant mice is due to a non-transferable mechanism(s), possibly functional clonal inhibition. Our data are compatible with a multi-step pathway involving both proliferating and non-proliferating helper T (Th) cells. In addition, the fine specificity of tolerance induction for DTH and Tprlf responses was examined by using the related antigens poly(Glu60Ala40) (GA) and poly(Glu50Tyr50) (GT). Tolerance is exquisitely specific, as GA tolerizes responses to GA and GAT, whereas GT tolerizes GAT but not GA responses. Thus, both the route and form of antigen administration are important to the induction and regulation of immune response in Ir gene-controlled systems. Possible mechanisms governing the Th/Ts balance and the induction of GAT-specific tolerance and suppression for cellular and humoral responses in adult responders are discussed.

Phase I study of the adoptive immunotherapy of human cancer with lectin activated autologous mononuclear cells

In previous in vitro studies, the authors showed that phytohemagglutinin (PHA) stimulated peripheral blood lymphocytes (PBL) from cancer patients to generate cells that were lytic for fresh autologous tumor but not for lymphocytes or lymphoblasts. Thus, after IRB approval, a phase I clinical protocol was instituted in cancer patients who had failed all other therapy to determine the toxicity and effects, in vivo, of the infusion of large numbers of such PHA activated autologous PBL. Ten patients were treated on the protocol, six with sarcoma, one with melanoma, and three with colorectal cancer. Up to a total of 1.7 X 10(11) PBL were obtained from 7 to 15 successive leukaphereses, the cells from each leukapheresis being incubated in vitro in medium containing PHA and human AB serum for 2 days and then reinfused following the next leukapheresis 2 days later. Toxicity encountered included fever and chills in 10/10 patients, headaches in 5/10, nausea and vomiting in 3/10, and requirement for erythrocyte transfusion in 8/10. No evidence for autoimmune disease, abnormal serum chemical or coagulation studies, or pulmonary emboli was found. 111Indium trafficing studies showed distribution of infused cells mainly to the spleen and liver, with some accumulation in the lungs and tumor especially after repeated infusions. In 9/10 patients, activated PBL were detected in the peripheral circulation by the sixth leukapheresis. Evidence for this was found by assaying the incorporation of tritiated thymidine (3H-Tdr) into, and lysis of fresh tumor cells by, unstimulated PBL from successive leukaphereses. No tumor regression was seen in these patients with bulk disease. These studies demonstrated that large numbers of PHA-activated PBL can be safely obtained and infused into humans, achieving an increase in the number of circulating activated cells with evidence of migration of cells to tumor, lungs, liver and spleen. Further studies of the use of activated lymphocyte infusion in conjunction with chemotherapy in humans are in progress.

Mechanisms of genetic control of immune responses. I. Evidence for distinct multi-step helper T-cell pathways in cellular and humoral responses to GAT

We examined multiple genetically regulated humoral and cell-mediated immune (CMI) responses to poly( glu60ala30tyr10 ) (GAT) using a panel of mouse strains. We show that assignment of responder/nonresponder status depends upon the assay method. In addition, two distinct categories of nonresponder mice were found: (1) those which are unresponsive by all parameters tested (H-2q and H-2s haplotypes) and (2) those which are partially nonresponsive [H-2bm12 mutant strain--a low/nonresponder by splenic plaque-forming cell (PFC) and delayed-type hypersensitivity (DTH) responses, but exhibits B6 parental levels of high GAT-specific T-cell proliferation ( Tprlf ) and interleukin-2 production]. The distinction between these two nonresponder types was confirmed by complementation tests in which significant GAT-specific PFC and DTH responses were seen in (H-2q X H-2bm12)F1 hybrids, but not in (H-2q X H-2s)F1 hybrids. Suppressor T cells (Ts) also play a selective role in nonresponsiveness to GAT. Cyclophosphamide treatment of nonresponders (to eliminate Ts activity) as well as immunization with GAT coupled to the immunogenic carrier MBSA result in the development of GAT-specific humoral, but not CMI responses. Our results indicate that the T cell is the cellular site of Ir gene expression and that Tprlf responses do not correlate with functional helper T-cell activity and suggest distinct, multi-step Th/Ts regulatory pathways in the development of humoral and CMI effector functions.

Absence of suppression in natural and induced tolerance to F antigen

The role of suppression in natural and induced tolerance to F antigen was investigated in two sets of experiments. In the first, CBA mice were submitted to pretreatments which decrease suppression and the antibody response to self- or allo-F type was investigated. The second set of experiments involved the transfer of spleen cells from tolerized or from naturally tolerant mice into normal mice which were then primed with allo-F, as well as the co-transfer of tolerant and primed lymphocytes into normal mice, to test whether tolerant lymphocytes present suppressor cells. The results indicate that the immune response against allo-F antigen is normally kept in a low level by a suppressive mechanism, and that F-specific suppressor T cells are absent from tolerant mice.

Detection in vivo 6 hours after immunization of a mediator with possible antisuppressor activity

Immunization of mice with foreign proteins or particulate antigen induces the formation of immunoglobulin (Ig)-antigen complexes which are strongly cytophilic for T cells and have been shown recently to markedly enhance the 7 S antibody response. In this report we demonstrate that pretreatment of the animals with cyclophosphamide or anti-I-J antiserum eliminates the difference in the antibody response between the mice injected with the complexes and the controls, in other words, the enhancement. Six hours after allogeneic stimulation the serum of mice contains also a cytophilic (for T cells) Ig which most likely represents, as in the case of the foreign antigens, complexes of Ig with alloantigens. The allogeneically induced 6-h serum (6HS) contains a factor which enhances the cytotoxic T lymphocyte(s) (CTL) response in vivo. As with the 7S antibody response, pretreatment of mice with cyclophosphamide, in doses known to eliminate suppressor cell expression, "masks" the CTL enhancement of the allogeneically induced 6HS. The same result was also observed with the anti-I-J antiserum. In conclusion, the 6-h complexes in cyclophosphamide- and anti-I-J-treated mice do not produce a 7 S antibody or CTL response above that produced by the control group (no complexes). Using heat-treated allogeneic tumor cells, known to induce suppressor cells in vivo, we have shown that for a low dose of tumor cells, the allogeneically induced 6HS did not block the induction of suppressor cells, but completely blocked their function. These results suggest that the enhancement of both humoral and cell-mediated immunity by the 6HS (complexes) is likely to be due to interference with normal suppressor cell function, that is, an antisuppressor mechanism.

Induction of delayed type hypersensitivity against ultrasonicated Mycobacterium lepraemurium bacilli without simultaneous local reactivity against live bacilli or protective immunity

Delayed type hypersensitivity (DTH) was induced in C3H mice by subcutaneous immunization with Mycobacterium lepraemurium (MLM) antigens in Freund's complete (FCA) or Freund's incomplete (FIA) adjuvant. The total ultrasonicate (MLMSon-P) of MLM bacilli as well as the water soluble fraction (MLMSon-S) of this ultrasonicate was found effective. MLMSon-S was used as the test antigen. Specific DTH also developed after immunization with heat-killed MLM bacilli in FIA, but not with heat-killed bacilli in saline. Some mice were pre-treated with cyclophosphamide (CY) or splenectomized to augment the effect of immunization. In no instance was DTH to MLMSon-S accompanied by detectable local reactivity to live MLM bacilli measured as swelling of the infected footpad or by reduced multiplication or dissemination of the bacilli during the first 11 weeks after inoculation. As determined by testing in the infected footpad 8 weeks after inoculation, MLM infection did not induce DTH to MLMSon-S in non-immunized mice, and MLM infection was found to neither augment nor suppress established DTH to MLMSon-S. The experiments thus demonstrated a clear dissociation between DTH to MLMSon-S and local reactivity to live MLM bacilli, as well as between DTH to MLMSon-S and protective immunity to MLM infection.

Inhibition of antigen-specific T lymphocyte activation by structurally related Ir gene-controlled polymers. Evidence of specific competition for accessory cell antigen presentation

The interaction of nominal Ag with major histocompatibility complex (MHC)-restricted T cells and accessory cells was studied by analyzing the effect of structurally related antigens on the response of antigen-specific MHC-restricted T cell hybridomas. The copolymer L-glutamic acid50-L-tyrosine50 (GT) completely inhibits the response of L-glutamic acid60-L-alanine40-L-tyrosine10 (GAT)-specific, I-Ad-restricted T cell hybridomas to GAT plus accessory cells. This inhibition is specific, as hybridomas of other specificities are not inhibited under identical conditions, and is unique to the GT antigen, as other similar copolymers are not inhibitory. The inhibitory effect is reversible by adding increasing amounts of GAT. Antigen-pulsing experiments localized the inhibition to the level of antigen-presenting cell (APC). GT-prepulsed APC are not inhibitory in cell-mixing experiments and can present other antigens. GT only inhibits the nominal antigen-directed component of a GAT-specific, autoreactive hybrid's response. Together these findings suggest that GT causes inhibition by competing for GAT association at the accessory cell. GT interferes with GAT presentation by an I-Adxb F1 APC to a BALB/c, I-Ad-restricted, but not B10, I-Ab-restricted, T cell hybridoma, and GT inhibits presentation by GAT-prepulsed APC. The implications of these findings for MHC-restricted presentation of antigen are discussed.

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

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

Polymorphism of T- and B-cell sensitization by aggregate-freed heterologous gamma-globulin

Female A/J, C57BL/6J, SJL/J, MRL/MpJ-+/+, MRL/MpJ-lpr/lpr, NZB/BINJ and male BXSB/MpJ mice were injected at various ages with a tolerogenic form of rabbit gamma-globulin, or were left untreated and all were then immunized with dinitrophenylated rabbit gamma-globulin. We could distinguish 4 types of responsiveness to sRGG: (1) persistent T-cell tolerance (A/J, MRL/MpJ-+/+); (2) persistent T-cell tolerance and age-dependent resistance and sensitization of B-cells to tolerance induction (C57BL/6J, NZB/BINJ); (3) decreasing T- and B-cell tolerance (SJL/J, male BXSB/MpJ); and (4) T-cell sensitization in older animals (MRL/MpJ-lpr/lpr). Suppressor capacity and its regeneration was examined in terms of colchicine and cyclophosphamide treatment. Colchicine increased the immune response to a much greater extent in 10-week-old than in 6-week-old MRL/MpJ-lpr/lpr mice and had little effect on MRL/MpJ-+/+ mice. It had a relatively small effect on 15-week-old NZB/B1NJ and a much greater effect on 6-week-old animals. The reason for these differences are discussed.

Characterization of a concanavalin A-induced amplifier T cell which augments in vitro antibody responses to DNP-Ficoll

The addition of the T-cell mitogen concanavalin A (Con A) on Day 2 of a 4-day in vitro culture of murine spleen cells with the thymus-independent (TI) antigen DNP39-Ficoll resulted in significant enhancement of the direct antitrinitrophenyl (TNP) plaque-forming cell (PFC) response. This enhancement was mediated by a nylon wool- and antiimmunoglobulin-nonadherent amplifier T cell (TA). TA activity was not eliminated by in vitro treatment of T cells with anti-Thy 1.2 and complement (C). TA activity could be eliminated by pretreatment of mice with antilymphocyte serum (ALS) in vivo, followed by in vitro treatment of T cells with anti-Thy 1.2 + C. Thus, TA appear to bear a low surface density of Thy-1 antigen. These TA were relatively resistant to ALS used alone, to cyclophosphamide, and to low dose in vitro irradiation. TA were still present in the spleen 14 weeks after adult thymectomy (ATx). They were I-J positive and apparently belonged to the Lyt 1+2- T-cell subset.

Immunology of metastasis. Can the immune response cope with disseminated tumor?

The application of immunologic methods to the treatment of neoplasia has been a goal of research in tumor immunology. Unfortunately, no clearly defined success for such therapy has been achieved. However, the most recent advances in tumor biology have provided for a more valid conceptual framework upon which to plan further research in this area. The more general awareness of tumor progression and heterogeneity, particularly in the context of tumor metastasis, while imposing a sense of gloom regarding all therapeutic modalities, shifted immunologic thinking toward the development of nonspecific modalities. We herein propose that this 'shift' may be premature and that immunotherapy using cytolygic T cells could still be feasible. Our views are based on newer approaches for selecting immunogenic variants of malignant tumors and a better understanding of the relationship of the immune response to metastases.

Delayed hypersensitivity responses to human IgG and methylated bovine serum albumin are regulated by different mechanisms

We found marked differences in in vitro and in vivo delayed hypersensitivity (DH) responses to human IgG (human gamma-globulin, HGG) and methylated bovine serum albumin (MeBSA). Lymph node cells (LNC) from cyclophosphamide (CY) pretreated, antigen-adjuvant immunized mice exhibited increased HGG-induced and decreased MeBSA-induced proliferative responses in vitro compared with LNC from similarly immunized but non-CY-pretreated animals. These effects were antigen-specific. Further, treatment of CY-HGG-adjuvant immunized mice with aqueous (aq) HGG either before or after immunization markedly suppressed HGG-specific in vitro proliferation and in vivo DH responses. Therefore, induction of suppression by aqHGG did not appear to depend on CY-sensitive cells either as a possible source of suppressor cell precursors or as participants in the regulatory events. In contrast, in vivo DH reactivity to MeBSA was unaffected by administration of aqMeBSA either before or after mice were immunized with CY-MeBSA-adjuvant. Our results suggest that DH responses to HGG and MeBSA are regulated by distinct mechanisms which influence the induction and the development of sensitivity.

Antigenic competition in IgE antibody production. II. Effect of cyclophosphamide

The effects of cyclophosphamide (CY) on antigenic competition in IgE antibody production were studied in mice treated with the drug on different days and immunized with a mixture of two non-related antigens. Injection of 100 mg of CY/kg of body weight 3 days before or 6 days after immunization resulted in a partial or total recovery of the IgE, but not of the IgGl antibody response to the test antigen. In contrast, when the same dose was given together or 3 days after immunization both responses were much more suppressed than in untreated animals. This same effect was obtained when a higher concentration (200 mg/kg) of cyclophosphamide was injected on day--3. When a different antigenic system was tested, the suppressive effects of competition in IgGl antibody production were also abolished after CY treatment. These results seem to provide further evidence for an important role of suppressor T cells in the mechanism of antigenic competition.

Conversion of immunity to suppression by in vivo administration of I-A subregion-specific antibodies

The in vivo administration of antibodies specific for gene products of the I-A subregion represents an immunologically specific approach to the manipulation of Ly-1+ T cell responses to antigen. This has been demonstrated previously by the capacity of anti-I-A antibody treatment to abrogate T cell-mediated delayed-type hypersensitivity (DTH) responses to syngeneic tumor antigen, hapten, and non-H-2 histocompatibility antigens. Evidence obtained in these studies suggested that the primary action of antibody was related to its ability to interfere with macrophage-T cell interactions during antigen presentation, consistent with the demonstration that similar antibodies inhibit T cell binding to antigen-pulsed macrophages in vitro. Results presented in this report provide evidence for an additional consequence of in vivo antibody administration that may be secondary to any direct effects on I-A-restricted antigen presentation. Thus, animals treated with I-A subregion-specific antibodies also develop a population of antigen-specific suppressor T cells (Ts) capable of inhibiting recipient Ly-1+ T cell responses to tumor antigen. The induction of suppression appeared to be an essential component of the total biological activity of these antibodies, because elimination of Ts precursors by cyclophosphamide also abrogated the antibody-mediated inhibition of DTH responsiveness. These results are discussed with respect to the possible mechanisms of Ts activation by anti-I-A antibody administration, and the general applicability of this approach as a means of clinical immunotherapy to limit inappropriate T cell responses in human disease.

The in vivo effects of interleukin 2 (TCGF)

This brief review of our experiments concerning the in vivo activity of crude Il-2 led us to the following conclusion: The first is the existence, in vivo, of a cyclophosphamide-sensitive T-cell controlling the activity of a serum born Il-2 inhibitor in thymus-bearing normal mice. Under in vivo conditions which are characterized by high Il-2 inhibitor activities, locally applied Il-2 administered along with antigen amplified in vivo CTL-responsiveness, yet the effect observed was poor. Crude Il-2 proved to be a potent immuno-enhancing agent in the athymic (nu/nu) mouse, which lacks Il-2 inhibitor activity. It was found that together with antigen administration of Il-2 to nude mice results in the generation of highly reactive T-helper cells, as well as in the generation of alloreactive CTL.

Age dependent differential effects of cyclophosphamide on natural antibody levels in chickens

Administration of 5 mg of cyclophosphamide per day for 4 days into neonatal chicks resulted in suppression of natural agglutinin titers up to at least 12 weeks of age. When the administration of cyclophosphamide was delayed until 7 days post-hatching suppression was found up to 8 weeks but titers rose to normal by 10 weeks after initial injections. Injections of cyclophosphamide after 21 days of age did not suppress natural agglutinin titers unless the drug was administered daily for 2 or more weeks.

In vitro effects of 4-hydroperoxycyclophosphamide on human immunoregulatory T subset function. I. Selective effects on lymphocyte function in T-B cell collaboration

The alkylating agent cyclophosphamide may suppress or enhance immune responses in vivo but is inactive in vitro unless metabolized by microsomal enzyme activation. 4-hydroperoxycyclophosphamide (4-HC) is a synthetic compound that is spontaneously converted in aqueous solution to the active metabolites. In this report, we examined the in vitro sensitivity of functional human T cell subsets to 4-HC in a polyclonal B cell differentiation assay and in the generation of mitogen-induced suppressor cells for effector B cell function. Con A-induced T suppression of B cell differentiation is completely abrogated by a 1-h pretreatment of T cells at very low concentrations of between 10(-2) and 20 nmol/ml, whereas inducer T cell function is sensitive only to concentrations in greater than 40 nmol/ml. The effects of 4-HC on suppressor T cells appear to occur at concentrations that do not result in DNA cross-linking or decreased blastogenesis. Con A-induced T suppressors are generated from within the OKT4+, OKT8- subset and are sensitive to low-dose 4-HC only before activation, whereas differentiated suppressor cells are resistant to concentrations in greater than 80 nmol/ml. Low-dose 4-HC pretreatment of the B cell population results in abrogation of immunoglobulin secretion when treated B cells are cocultured with unfractionated T cells, however, this effect is completely reversible if pretreated B cells are cocultured with T cells devoid of suppressor activity. These results demonstrate that human presuppressor cells for B-effector function differentiate in response to Con A from the OKT4+, OKT8- subset and are exquisitely sensitive to low concentrations of CYP whereas mature suppressor and inducer functions are resistant to all but very high concentrations in vitro. The differential sensitivity of functional T and B cell subsets to 4-HC in vitro can be a very useful probe in dissecting immunoregulatory interactions with man.

Selective action of alkylating agents against cells participating in suppression of antibody responses

The effect of several alkylating agents on the induction and expression of specific suppressor cell activity induced by supraoptimal immunization (SOI) with (4 x 10(9) ) SRBC was studied. Splenocytes taken 8-28 days after SOI and transferred to normal syngeneic recipients together with optimal dose of (3 x 10(8) ) SRBC caused 70-90% suppression. By contrast splenocytes harvested 2 days after SOI did not exert a significant suppressive effect. Treatment of donor mice with 30 mg/kg BCNU, CCNU, or MeCCNU, 8 mg/kg Melphalan or as much as 200 mg/kg Cy 2 days before SOI uniformly had no effect on the subsequent development of suppressor cells. By contrast, different drugs had diverse effects when injected after SOI: both BCNU and Cy injected 2 days post SOI alleviated suppression, whereas CCNU, MeCCNU and Melphalan injected 2 days post SOI were without effect. Another diversity between BCNU and Cy was noticed when the administration of drugs was delayed further. While Cy alleviated suppression 12 days post SOI, BCNU was ineffective at this time. Dose response and time course studies revealed that the effect of Cy was most severe when injected 2 days post SOI and gradually diminished with the passage of time after SOI. These results have been discussed in the light of the current concepts of multiple cell participation in the induction and expression of suppressor cell function.

Two distinct high immune response phenotypes are both controlled by H-2 genes mapping K or I-A

Murine responses to immunization with 2, 4, 6-trinitrophenyl (TNP) conjugated to autogenous mouse serum albumin (MSA) in complete Freund's adjuvant (CFA) are controlled by a gene(s) in the K or I-A region of H-2 complex. High immune responses of both H-2d and H-2b mice have been mapped to this region of the major histocompatibility complex. No modifying effects were observed from genes to the right of I-A in either responder haplotype. High responsiveness controlled by Kb or I-Ab is inherited with complete or partial recessivity, depending on the route of immunization and the sex of the responder. However, high responsiveness controlled by Kd or I-Ad is inherited dominantly. This unusual pattern of inheritance of immune responsiveness to TNP-MSA is consistent with the genetic mapping to K or I-A. TNP-MSA-specific T-cell reactivity following immunization with TNP-MSA in vivo was examined utilizing a T-cell-dependent proliferation assay in vitro with cells obtained from high or low responder mice. Genetic mapping and mode of inheritance in this assay for antigen-specific T-cell reactivity corresponded with results obtained from a plaque-forming cell (PFC) assay measuring antibody production by B cells. Both the proliferative and PFC responses are probably under the same Ir gene control. Both gene dosage effects and Ir-gene-product interaction could influence the generation of specific immune responsiveness in F1 hybrids between high and low responders to TNP-MSA.

B and T cell involvement in anti-acetylcholine receptor antibody formation in myasthenia gravis

The in vitro method of antibody production was applied to ascertain the contribution of B and T cells to the formation of anti-acetylcholine receptor (AChR) antibody. The anti-AChR antibody in the culture supernatant was estimated by radioimmunoassay, and the anti-AChR antibody-forming cells from cultures were detected by autoradiography of the antigen-binding cells. Thymic B cells from myasthenia gravis (MG) patients formed antibody when they were cultured with thymic T cells from MG patients and stimulated with AChR antigen. The antibody formation was more vigorous with thymic B cells, which contained more germinal centres. The antibody was also formed from the B and T cell combination of peripheral blood lymphocytes, although the amount was less than that produced by thymic lymphocytes from MG patients. The antibody produced by lymphocytes from MG patients. The antibody produced by lymphocytes from MG patients was suppressed by the addition of T cells from the culture supernatant of normal individuals, but not by autologous or allogeneic T cells from MG patients. The suppression by T cells from normal individuals was abolished when the cells were treated with mitomycin C. These observations indicated that AChR-specific B cells and helper T cells are active, while the suppressor T cells, which are usually present in normal individuals, are defective in MG patients.

Suppressor pathways in tumor immunity: a requirement for Qa-1 positive tumor-bearer spleen T cells in suppression of the afferent immune response to tumor antigens

Spleen cells from mice bearing large methylcholanthrene (MCA)-induced sarcomas were injected intravenously into mice challenged in the hind footpads with heavily-irradiated cells from the same or a different sarcoma. As measured by [3H]-thymidine incorporation on day 5 or 6, cellular proliferation in the draining popliteal lymph nodes of these mice was significantly depressed as compared to control animals receiving normal spleen cells or medium intravenously. The suppression was found to be mediated by a Qa-1-positive, Thy-1 positive cell. It was relatively resistant to cyclophosphamide treatment (100 mg/kg). Furthermore, it had both antigen-specific and non-specific components. The findings are discussed in relation to a suppressor activator cell-suppressor acceptor cell pathway in the immunoregulation of tumor immunity.

Lyt-23+ cyclophosphamide-sensitive T cells regulate the activity of an interleukin 2 inhibitor in vivo

Sera of thymus-bearing normal mice contain high levels of Interleukin 2 (II-2) inhibitor, whereas sera of athymic nu/nu mice do not. Evidence is presented that cyclophosphamide-sensitive Lyt-23+ T cells induce high II-2 inhibitor activity in the recipient nu/nu mice in the course of a graft-vs.-host reaction. The II-2 inhibitor has an approximately 50,000 mol wt. Its function is neither antigen specific nor H-2 restricted. During ontogeny, its activity parallels the development of T cell reactivity, i.e., it is absent both in the amniotic fluid and in sera of unborn mice, but increases to high levels during the early postnatal phase. The II-2 inhibitor described is viewed as an example of a T cell-dependent, in vivo regulatory mechanism able to effectively counteract the nonspecific activity of the Lyt-1+ helper T cell-derived II-2. Because the II-2 inhibitor activity is rather high in vivo, II-2 activity will exist only in close proximity to its producer cell, thereby maintaining specificity during the in vivo induction of cytotoxic T lymphocytes

On the nature of susceptibility to cancer. The presidential address

The most prominent factor determining susceptibility to cancer is age. However, there is little evidence that the aging process per se increases susceptibility to cancer. Rather, age provides the time necessary for the accumulation of cellular events required for the development of neoplasia. The variations in the patterns of cancer incidence rates seen with age can be explained by alterations in conditions of exposure to carcinogenic stimuli. There is no evidence that the pool of susceptible individuals in a population is limited. Cancer occurs as a random event in a population with greater or lesser frequency according to the presence of risk factors. In populations with an increased frequency of cancer such as those with genetic abnormalities, immune deficiency syndromes, or altered hormonal states, the risk of developing cancer is never generalized to all tissues but is characteristic of particular tissues at risk. Any circumstance of internal or external origin that disturbs homeostasis of particular tissues at risk. Any circumstance of internal or external origin that disturbs homeostasis over a prolonged period of time increases the susceptibility to cancer for the tissue concerned. Susceptibility to cancer does not mean that cancer is inevitable. Only a small number of those susceptible to cancer by virtue of a special risk factor develop the disease. Furthermore, most patients who develop cancer have no determinable risk factors. Although all evidence points to a multifactorial, multistage process, the rate of somatic mutation appears to be the key determinant factor in susceptibility to cancer. This concept is supported by research studies showing that the onset of atherosclerosis is initiated by somatic mutations, and the finding that the same chemical mutagens can advance the development of both diseases.

Antigen-specific T cell-mediated suppression. V. H-2-linked genetic control of distinct antigen-specific defects in the production and activity of L-glutamic acid50-L-tyrosine50 suppressor factor

The occurrence of distinct genetic defects affecting the generation of T cell-derived suppressor factor (TsF) or the suppressive activity of such TsF was investigated. For the synthetic polypeptide L-glutamic acid50-L-tyrosine50 (GT), it could be shown that the nonsuppressor strain A/J fails to produce suppressor T cells (Ts1) capable of GT-TsF generation upon challenge with GT. Conversely, B6, another nonsuppressor strain, produces GT-TsF active on other allogeneic strains such as A/J, but itself fails to be suppressed by this material. (B6A)F1 mice both make GT-TsF, and are suppressed by it. Further experiments revealed that the production of GT-TsF and the ability to be suppressed by GT-TsF are under the control of H-2-linked genes. Finally, the defect in GT-TsF activity in B6 mice was shown to be exquisitely antigen specific, in that this strain can be suppressed by a closely related TsF specific for L-glutamic acid60-L-alanine30-L-tyrosine10. It is suggested that H-2 (I) control of suppressor T cell (Ts) activity may reflect the involvement of I-A and I-C gene products in antigen presentation to Ts in analog with other T cell subsets, and that TsF function might also involve such presentation, in this case of the idiotypic structures of the TsF-combining site. Predictions deriving from this hypothesis are discussed, including the possibility that H-2 linked immune response genes regulate auto-anti-idiotypic responses in immune networks.

Effect of 1-beta-D-ribofuranosyl-1,2,4-triazole-3-carboxamide (ribavirin) on tolerance induction in SJL mice

The effect of 1-beta-D-ribofuranosyl-1,2,4-triazole-3-carboxamide (ribavirin) on tolerance induction with rabbit gamma globulin (RGG) was investigated. The treatment with ribavirin, initiated on the 4th and 17th day of life, did not reduce the immune response significantly, but provided a much more profound level of tolerance than could be achieved in animals not treated with ribavirin. When treatment with ribavirin was initiated at the age of 50 or 65 days, the response of immunized animals was reduced and the response of tolerized-immunized animals was increased. The mechanism, underlying the drug action, was discussed in terms of an effect or ribavirin on the balance between help and suppression; the possibility that a virus may be involved in age-dependent changes and that ribavirin prevents it proliferation, was considered.