Depression of the antibody response in Pseudomonas aeruginosa-injected mice.

Heat-killed Pseudomonas aeruginosa inhibit antibody response in C57BL/6 mice. The depression of this response is dependent on the dose of bacteria injected, on the time interval between microorganism injection and antigen administration, and on the nature of the antigen used. Cell transfer experiments provide evidence that suppressor cells are not operative in this model. Furthermore, the results show that P. aeruginosa induces a marked dose-dependent proliferation of spleen cells in vivo, and the in vitro targets of this proliferative effect are B lymphocytes. It is suggested that whole, heat-killed P. aeruginosa in vivo also behave as cell mitogens on B lymphocytes which, when strongly stimulated to proliferate, temporarily lose their capacity to mount a normal antibody response.     

Depression of contact sensitivity and enhancement of antibody response in Pseudomonas aeruginosa-infected mice.

The effect of Pseudomonas aeruginosa infection on contact sensitivity to 2-phenyl-4-ethoximethylene-oxazolone (oxazolone) and on antibody response to sheep erythrocytes, horse erythrocytes, and Escherichia coli 0111:B4 lipopolysacharide was investigated in outbred C57BL/6 mice. Injection of 0.5 and 0.2 median lethal doses significantly depressed contact sensitivity to oxazolone, whereas injection of 0.5 median lethal dose of heat-killed microorganisms did not. The filtrate of a 24-h broth culture did not affect contact sensitivity as well. Antibody production against sheep erythrocytes, horse erythrocytes, and lipopolysaccharide (evaluated as plaque-forming cells and circulating hemagglutinin and hemolysin titers) was found to be significantly enhanced both in animals injected with living bacteria and in those which received heat-killed microorganisms. The simultaneous occurrence of depression of cell-mediated immunity and potentiation of humoral response suggests that P. aeruginosa might interfere at different levels of the host immunological responsiveness.     

Pseudomonas aeruginosa infection depresses contact sensitivity to oxazolone by enhancing suppressor cell activity

The depression of contact sensitivity to oxazolone in mice infected withPseudomonas aeruginosa was studied. In oxazolone-sensitized mice,P. aeruginosa infection affects cell proliferation in the lymph nodes draining the site of sensitization. This impaired cell proliferation does not seem to be due to an altered lymphocyte reactivity, since lymph node and spleen cells from infected animals show a normal mitotic responsiveness to both T and B cell mitogens. In addition, the draining lymph nodes and spleens of mice exhibiting a depressed response to oxazolone contain a cell population able actively to suppress the response to the same antigen of syngeneic recipients sensitized immediately before the cell transfer. These suppressor cells require antigenic stimulation and appear to act on the induction phase of contact sensitivity.     

Depression of contact sensitivity by Pseudomonas aeruginosa-induced suppressor cells which affect the induction phase of immune response.

The cellular basis of depression of contact sensitivity to oxazolone in mice injected with Pseudomonas aeruginosa was studied. Cells from draining lymph nodes of mice sensitized with oxazolone 18 h previously were able to induce contact sensitivity to normal mice when administered in their footpads. In contrast, cells from draining lymph nodes of P. aeruginosa-injected and oxazolone-sensitized donors failed to induce contact sensitivity when injected in the footpad of normal mice and were capable of actively blocking the immunizing process brought about by lymph node cells from sensitized mice when injected together in the footpad of normal recipients. The P. aeruginosa-induced suppressor cells required antigenic stimulation, had precursors sensitive to cyclophosphamide, and did not affect the effector mechanisms of contact sensitivity. Thus, the results suggest that P. aeurginosa depresses contact sensitivity to oxazolone by enhancing the activity of suppressor cells which normally arise during the sensitization process and which affect the afferent limb of the immune response, probably by inhibiting the normal recruitment of T lymphocytes in the draining lymph nodes.     

Staphylococcus aureus inhibits contact sensitivity to oxazolone by activating suppressor B cells in mice

Killed Staphylococcus aureus strain Cowan I cells inhibit contact sensitivity to oxazolone in mice, when given intravenously 24-72 h before sensitization. With transfer experiments it was found that the cells responsible for the suppression are antigen-specific, nylon-adherent, resistant to antitheta serum + C, and sensitive to anti-mouse Ig serum + C. These suppressor B cells bear anti-oxazolone immunoglobulins and appear to exert their suppressive activity by preventing the contact sensitizer from reaching the specific reactive T cells.     

Specific and non-specific suppressor cell activity in NZB mice.

Non-specific and specific suppressor cell activity has been examined in both young and old NZB mice and compared to normal CBA mice. Both young and old NZB mice are shown to be able to generate antigen non-specific and specific suppressor cells in response to Con A and rat RBC respectively. In addition, antigen-specific suppressor cells which suppress the experimental induction of red cell autoantibodies do not influence the spontaneous development or course of autoimmune haemolytic anaemia. Subsequent experiments showed that this is probably due to differences in specificity of induced and spontaneous autoantibodies.     

Analysis of the T suppressor cell circuit which regulates contact sensitivity in mice infected with the virus of Newcastle disease.

The interaction between the virus of Newcastle disease (NDV) and the different cellular elements involved in the T suppressor cell circuit which regulates the expression phase of contact sensitivity has been investigated. NDV does not interfere with the production of the antigen-specific T suppressor factor (TsF) but inhibits its binding to T acceptor cells (Tacc). This cell when armed with TsF and exposed to the antigen corresponding to TsF releases a non-specific inhibitor of the transfer of contact sensitivity. More detailed analysis of the effect of NDV on the Tacc system showed that not only Tacc activity is impaired by NDV, but also the ability of antigen presenting cells (APC) to trigger Tacc armed with TsF is inhibited. The impairment of APC activity by NDV has been also investigated using another system, such as the induction of contact sensitivity by footpad cell transfer. The possibility that a virus-induced membrane modification might be responsible for the effect of NDV on the regulation of contact sensitivity is discussed.     

Pharmacological modulation of suppressor cell activity in mice with disseminated histoplasmosis.

Indomethacin and cyclophosphamide (CY) were used in an attempt to modify the suppressive effects of spleen cell populations from mice with disseminated histoplasmosis at 1 week of infection. In vitro addition of indomethacin did not alter the depressed plaque-forming cell response to sheep erythrocytes of normal spleen cells cocultured with unfractionated or nylon wool-fractionated spleen cells from infected mice. Likewise, indomethacin given intraperitoneally did not enhance the subnormal in vivo plaque-forming cell response of spleen cells from infected mice. Conversely, 20 mg of CY per kg given intraperitoneally 2 days before or 6 h after the inoculation with Histoplasma capsulatum partially reversed the suppression effected by splenic T cells (nylon wool passed) in vitro, whereas 50 mg of CY per kg given intraperitoneally 6 h after the injection of H. capsulatum ablated suppressor T cell activity in vitro; neither dosage of CY altered the suppression mediated by unseparated or nylon wool-adherent spleen cells. Furthermore, the administration of 50 mg of CY per kg failed to improve the depressed footpad responses of mice infected for 1 week to sheep erythrocytes in sheep erythrocyte-sensitized mice or to histoplasmin. These findings indicate that in experimental disseminated histoplasmosis, suppression effected by splenic T cells can be alleviated by CY; however, there is a persistent immunosuppressor mechanism(s) that cannot be counteracted by either indomethacin or CY.     

Inhibitory effects of interferon-gamma on the T suppressor cell circuit in contact sensitivity

The effects of a partially purified, splenocyte-derived murine interferon (MuIFN-gamma N) and a recombinant IFN-gamma (MuIFN-gamma R) on the T suppressor pathway and on the T effector cells of delayed type hypersensitivity were investigated in a 2,4-dinitrofluorobenzene contact sensitivity model. Various T cell subpopulations, suppressor T cells of afferent and efferent types, and an auxiliary T suppressor cells as well as a T effector cell of delayed type hypersensitivity were induced and the functions assessed in transfer experiments. Confirming the results of earlier experiments obtained with IFN-alpha, beta, the MuIFN-gamma N preparation and the rec. MuIFN-gamma R: enhanced the decreased response in animals sensitized with an antigen overload to an optimal response; inhibited the afferent-acting T suppressor cell in vivo and in vitro; inhibited the Ts-eff response; blocked the auxiliary T suppressor cell response after intravenous injection to recipients of Ts-eff cells on day 0 and 1; and did not suppress the activity of the T effector cell of delayed type hypersensitivity in vivo and in vitro (the MuIFN-gamma R was not tested). We conclude that IFN-gamma preferentially inhibited the T suppressor cell circuit of contact allergy. These results are similar to our observations on the inhibitory effects of a pure interferon-alpha, beta on the regulatory T suppressor cell circuit in contact allergy. Selective suppression of different T subpopulations by IFN-gamma may be an important regulatory mechanism in delayed type hypersensitivity.     

雷公藤片诱导小鼠脾脏抑制细胞活性的研究

本文从体内及体外两方面探讨了雷公藤片对小鼠脾脏抑制细胞活性的影响。雷公藤片0.2克/日/只灌胃5天及9天后,小鼠脾脏抑制细胞活性明显增高,达26.9±23.9%及37.9±22.7%;与正常对照组相比(-14.4±37.9%)差异非常显著(P<0.01)。而给药12及15天后抑制细胞活性则有的明显增高,有的明显降低。给药5天后脾细胞对ConA应答明显降低。停药后7天,小鼠脾细胞对ConA应答已部分恢复,但抑制细胞活性仍然保持在较高水平。雷公藤片体外诱导2天后的脾细胞可明显抑制正常脾细胞对ConA的应答,抑制率达47.0±14.8%。本文还对雷公藤片的作用机理加以初步探讨。     

Macrophage suppressor factor in contact sensitivity. Mechanisms of its release and action.

An antigen-specific suppressor factor (TSF) produced by mouse T lymphocytes prevents immune cells from conferring adoptive immunity on normal recipients. This TSF attaches easily to the macrophage surface, and these 'armed' macrophages in the presence of a corresponding antigen manufacture (in vitro) a non-specific macrophage suppressor factor (MSF) which impairs the activity of cells sensitized to homologous or heterologous antigens. Our experiments show that MSF is temperature- and trypsin-sensitive, and is not a prostaglandin. Its molecular weight is in the range of 10 kD. MSF is synthesized by macrophages de novo subsequent to triggering by TSF and antigen. MSF impairs only the activity of cells mediating contact sensitivity reaction (Ly 1) but has no influence on T-suppressor cells (Ly 23). The possibility that MSF is an enzyme is discussed.     

Central and peripheral action of suppressor cells in contact sensitivity in the guinea-pig.

Suppressor cells were demonstrated in the spleen of guinea-pigs made specifically unresponsive to dinitrofluorobenzene (DNFB) with dinitrobenzene sulphonic acid (DNBSO3). Transfusion of these cells at the same time as sensitization with DNFB, produced a significant reduction in the immunoblasts proliferating in the draining lymph node 4 days later. Transfusion on the day of skin testing produced no greater suppression of skin reactivity than cells taken from animals made hypo-reactive to DNFB by contact with dinitrothiocyanate benzene (DNTB). It is concluded that there are at least two sites that suppressor cells can act. In the case of total unresponsiveness induced by DNBSO3, action is both central and in the periphery. In the case of hyporeactivity induced by DNTB, in which there is no defect in proliferation of T cells in response to antigen, the action of these cells is confined to the periphery. results of spleen weight studies suggest that suppressor cells homing in the spleen respond by proliferation to epicutaneously applied DNFB.     

Nonspecific macrophage suppressor factor: its role in the inhibition of contact sensitivity to picryl chloride by specific T suppressor factor.

Anti-picryl T suppressor factor was produced by culturing lymphoid cells from mice which were first injected with picryl sulfonic acid and then painted with picryl chloride. The supernatant was harvested at 48 h. Macrophage suppressor factor was produced by incubating peritoneal exudate cells (PEC) in T suppressor factor, washing and then adding antigen and taking the supernatant after incubation for 1 h. Immune cells incubated in the supernatant lost the ability to transfer contact sensitivity. The supernatant (macrophage suppressor factor) was nonspecific and inhibited the passive transfer of contact sensitivity to picryl chloride and oxazolone to a similar extent. Macrophage suppressor factor was only produced when PEC were incubated in anti-picryl T suppressor factor and then exposed to picrylated antigen. Syngeneic thymocytes picrylated in vitro were the best source of antigen. Allogeneic thymocytes and regional lymph node cells picrylated in vivo by painting with picryl chloride were less effective. Picrylated mouse red blood cells and picrylated mouse gamma globulin were least effective. Macrophage suppressor factor differed from T suppressor factor in several ways. It was nonspecific, its molecular weight was lower (10000–20000 daltons), and it failed to bind to PEC. It also failed to bind to immune cells at 0°C. Although macrophage suppressor factor inhibited passive transfer when the mice were tested immediately afterwards (Chase-Landsteiner transfer), it did not affect passive transfer when testing was delayed for a week. It is proposed that macrophage suppressor factor amplifies the effect of T suppressor factor.     

Antigenic competition in the induction of contact sensitivity in mice.

Antigenic competition in contact sensitivity was found to occur between DNFB and PCl and also between some other pairs of non-cross reacting sensitizers. When mice were painted with DNFB 0-7 days before the sensitization with PCl, the responsiveness to PCl was suppressed completely, whereas when DNFB was painted after sensitization with PCl, the responsiveness to PCl was affected. The prior application of DNFB resulted in the reduction of DNA synthesis in the draining lymph nodes of PCl-sensitization. This indicated that the suppression by painting with DNFB was not attributable to the inactivation of PCl-specific effector T cells which had already been generated by the sensitization with PCl, but to the inhibition of the generation of PCl-specific effector T cells. The antigenic competition occurred even when two contact sensitizing agents were applied to different lymphoid regions of mice. The suppressive effect of DNFB on the PCl-sensitization was observed also in the mice which had been made tolerant to DNFB. These results seem to imply that the antigenic competition in the present experimental system is the phenomenon which may not be mediated by effector T cells but rather by other cells, possibly suppressor cells.     

Inhibition of contact sensitivity by interferon in mice infected with lactic dehydrogenase virus.

The effect of acute lactic dehydrogenase virus (LDV) infection was studied with respect to contact sensitivity (CS) to 2,4-dinitrofluorobenzene (DNFB). CS reaction was severely inhibited in the acute phase but not in the chronic phase of infection. The role of interferon (IFN) was studied to understand further the inhibition of CS during LDV infection. IFN in the blood was detected only in the acute phase, but not in the chronic phase of infection. When anti-IFN (alpha/beta) was administered to infected mice, no inhibition of CS was seen. CS was inhibited in uninfected mice treated with IFN (alpha/beta). These results suggest that IFN production in the blood may be responsible, at least in part, for inhibition of CS observed in the acute phase of LDV infection.     

Reduction of contact sensitivity reactions to oxazolone in mite-infested mice.

Oxazolone-sensitized mite-infested (SWR-M) and mite-free (SWR-J) mice were challenged with oxazolone on the skin of the neck and shoulder. The migration of radioactively labeled cells to the site of contact sensitivity reaction to oxazolone was significantly less in SWR-M than in SWR-J mice. Serum obtained from SWR-M mice suppressed the extravasation of cells into the skin site of SWR-J mice challenged with oxazolone. The decrease in cellular influx in SWR-M mice occurred in areas of mite infestation (skin of neck and shoulder) as well as in areas not infested with mites (the ears). SWR-M mice also gave evidence of enhanced vascular permeability. A possible role for histamine in the inhibition of contact sensitivity in mite-infested mice is discussed.     

Sex differences in regulation of contact sensitivity reaction in mice. 1. Influence of sex on the generation of contrasuppressor and afferent suppressor cells

It is well known that humoral and cell-mediated immune responses are better in females than in males. Females also develop autoimmunity more easily than males. Contact sensitivity, one of the forms of cell-mediated immunity, is controlled at the afferent and efferent phases by complex interactions of regulatory T cells. Our present experiments indicate that T suppressor afferent (Ts-aff) and T contrasuppressor cells (Tcs) are generated in the mouse in a sex-dependent fashion. These two types of regulatory cells are induced by antigen-antibody complexes containing various immunoglobulin isotypes. Females require fewer antigen (Ag)-IgG1 complexes to produce Tcs cells, but more Tcs cells after antigenic stimulation in females tips the balance toward better immune responsiveness. It remains to be established whether the peculiarities in generation of regulatory cells in female mice are relevant to the pathogenesis of autoimmune diseases which predominantly affect females.     

Circulating suppressor factors in mice subjected to ultraviolet irradiation and contact sensitization.

BALB/c mice subjected to a single dose of UV-B radiation showed suppressed contact hypersensitivity to trinitrochlorobenzene. The in vitro antigen reactivity of peritoneal cells from these mice was investigated using the leucocyte-adherence inhibition assay. These cells showed a high degree of reactivity with specific antigen. However, this reactivity, but not the reactivity of cells from non-irradiated sensitized mice, could be suppressed by serum from UV-treated sensitized mice. The suppressive effect of this serum could also be demonstrated on other syngeneic systems with unrelated antigens and was partially effective with allogeneic cells, indicating a lack of antigen specificity and genetic restriction. Suppressive properties were also found in serum taken from mice 3-5 days (but not at other times) after irradiation without subsequent sensitization.     

Decreased suppressor cell activity in inflammatory bowel disease.

Studies were performed on eleven patients with inflammatory bowel disease to determine if there was an alteration in concanavalin A (Con A) induced suppressor cell activity. Similar investigations were also performed on twenty-one control subjects and five patients with other inflammatory conditions. Supressor cells were generated by pre-incubation of peripheral blood mononuclear cells with a mitogenic concentration of Con A, followed by treatment with mitomycin C and alpha-methyl mannoside. Under these conditions, cells obtained from normal individuals are then capable of suppressing the Con A-stimulated blast transformation responses of fresh allogeneic lymphocytes in new cultures. We found that in twenty out of twenty-one control subjects, and all five patients with other inflammatory disorders, Con A-stimulated suppressor cell activity was demonstrable. Four patients with inflammatory bowel disease, whose disease was mildly active or was in clinical remission, had elicitable suppressor cell activity which fell within the normal range. In contrast, suppressor cell activity was markedly diminished or absent in seven patients with severe and active inflammatory bowel disease. These studies suggest that an alternation in Con A-stimulated suppressor cells exists in patients with active inflammatory bowel disease, which may contribute, in part, to the persistent inflammation in the gastrointestinal tract.