Effect of aging on autoimmune response to rat male accessory glands: young, but not aged, antigen-presenting cells efficiently induce suppression in aged rats.

The present report analyzes the suppressor cell system of aged rats in an experimental model of autoimmunity to rat male accessory glands (RAG). A state of specific suppression to RAG was induced when young rats are pretreated with peritoneal cells (PC) obtained from syngeneic young rats i.p. injected 2 h previously with chromatographic fraction I (Sephadex G-100) (FI) of RAG (yFI-PC). Although the yFI-PC injection diminished the DTH in aged rats the autoimmune response remained positive. Peritoneal cells obtained from aged rats injected with FI of RAG (oFI-PC) did not suppress the DTH response in either aged or young rats. In both young and aged, pretreatment with yFI-PC stimulates spleen cells capable of inducing suppression (inductor-phase suppressor cells) when they are transferred to young recipients. However, the spleen inductor-phase suppressor cells of 12-month-old rats are unable to suppress the autoimmune response in their own aged environment. To obtain effective suppression in 12-month-old rats, the injection of yFI-PC was necessary prior to and subsequent to immunization. In this work we observe that 12-month-old rats could efficiently induce inducer phase and effector-phase suppressor cells when the adequate young antigen-presenting cells were present to stimulate them.

Adoptive transfer of suppression of the autoimmune response to rat male accessory glands: characterization of the suppressor cells.

We have examined the mechanism of suppression of autoimmunity to rat male accessory glands (RAG) by T suppressor cells. This suppression was accomplished by transfer to syngeneic rats of spleen mononuclear (SpM) cells from rats rendered unresponsive by pretreatment with low doses of a purified fraction of RAG (containing the autoantigen). The experiments demonstrated that the suppressor cells that act on the inducer phase of the suppression are cyclophosphamide (Cy) sensitive and that they can be positively selected on antigen-coated plates. On the other hand, the inducer phase T suppressor cells present on spleens coming from antigen-pretreated rats did not suppress the autoimmune response in normal recipients that had been irradiated (850 rad 137Cs) just prior to receiving the cells or injected with Cy 14 days after transfer. The results indicate that the regulation of immune response to the autoantigen of RAG is complex and that it involves the interaction of many cell types.

Antigen-induced inhibition of the autoimmune response to rat male accessory glands: bone marrow dependence of the enhancement of IA+ but not IE+ antigen-presenting cells.

IE+ peritoneal cells (PC), involved in the induction of suppression of autoimmune response to rat male accessory glands (RAG), are obtained from rats 2 h after i.p. injection of a purified fraction (FI) of RAG (FI-PC2h). In contrast, IA+ PC, involved in the induction of autoimmune response to RAG, are obtained from rats 24 h after FI of RAG injection (FI-PC24h). The present report analyzes the effect of irradiation or irradiation/bone marrow reconstitution on the induction of both populations of PC. Peritoneal cell donor rats were irradiated in a telegamma therapeutic Cs137. Twenty hours later half of them were i.v. reconstituted with 40 x 10(7) bone marrow cells. Six days later rats were i.p. injected with 200 micrograms of FI of RAG and 10(7) resident PC. The PC were harvested 2 h or 24 h later. The ability of resident PC to yield IE+ FI-PC2h involved in the induction of suppression is not impaired by irradiation, but the ability of resident PC to yield IA+ FI-PC24h involved in the induction of a positive response is impaired by irradiation and restored by bone marrow reconstitution of irradiated rats. Culture of normal PC with FI of RAG for 2 h or 24 h shows a selective increase in IE+ cells able to induce suppression to RAG.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of thymus supernatants on the phenotype of different subsets of peritoneum antigen-presenting cells.

Peritoneal cells (PC) obtained 2 h subsequent to intraperitoneal (i.p.) injection of low doses (200 micrograms) of a purified fraction of rat male accessory glands (FI-RAG) are phenotypically and functionally different from those obtained 24 h after i.p. injection. In fast, PC obtained 2 h after FI-RAG injection are mainly IE+ and are involved in inducing specific suppression to RAG. In contrast, PC obtained 24 h after FI-RAG injection are mainly IA+ and capable of inducing specific response to RAG. For their induction, IA+ PC require cells within or recently derived from bone marrow. In order to analyze the mechanisms involved in IA+ bone marrow-dependent cell generation in the peritoneum, we studied the distribution of FI-RAG following i.p. injection. It was established that FI-RAG is found mainly in the thymus 2 h after injection and remains there for at least 24 h. Subsequently, we analyzed, in 4 groups of rats, the influence of thymic culture supernatants on the phenotype of cells appearing in the peritoneal cavity 2 h after FI-RAG injection. An increase in IA+ PC was observed 2 h after i.p. injection of FI-RAG in animals that had received either supernatants from normal thymic cells cultured with FI-RAG or those from thymic cells taken from animals injected with FI-RAG 2 h prior to being killed. Supernatants of thymic cells from animals injected with FI-RAG 24 h prior to being killed or from normal thymic cells do not increase the percentage of IA+ PC.(ABSTRACT TRUNCATED AT 250 WORDS)

Enhanced myocardial lesions in chronically Trypanosoma cruzi-infected rats subjected to adult thymectomy.

Control animals and rats infected 90 days earlier, by inoculation of 1 x 10(6) trypomastigotes of Trypanosoma cruzi at weaning, were subjected to adult thymectomy (ATx) or sham operation (S-ATx) and assessed 3 months later for the presence of myocardial lesions and levels of lymph node and spleen T-cell populations. Chronic focal myocarditis (CFM) developed in 78% and 84% of S-ATx or ATx infected rats, respectively. While the two groups of infected rats did not differ as to the occurrence of myocardial lesions, large foci of CFM were more prevalent in ATx infected rats. Chronic T. cruzi (Tc) infection resulted in decreased CD4+ and increased CD8+ lymph node and spleen cell, with CD8+ lymphocytes being lowered to normal values in the spleen of the ATx infected group. It is suggested that ATx might act by interfering with a down-regulating immunoregulatory mechanism, leading to an exacerbation of autoimmune reactions believed to be involved in the generation of myocardial damage.

Antigen-induced inhibition of autoimmune response to rat male accessory glands. Role of macrophages in the induction of suppressor cells.

The present paper describes a mechanism responsible for the induction of inducer-phase suppressor cells effective to suppress the autoimmune response to rat male accessory glands (RAG). In fact, we reported here that marked suppression of delayed type hypersensitivity (DTH) reaction and humoral response to chemically modified rat male accessory glands (MRAG) can be obtained when previously to be immunized with MRAG in complete Freund's adjuvant (CFA) syngeneic rats were pretreated with peritoneal cells (PC) coupled with a purified fraction of RAG (containing the autoantigen). The involvement of MRAG-specific inducer-phase suppressor cells was demonstrated by adoptive transfer experiments of spleen mononuclear cells from unresponsive donors to normal syngeneic rats 24 h prior to immunization of the recipients with MRAG-CFA. The PC used to treat the animals show a large proportion of non-specific-esterase positive, Ox-41 bearing macrophage-like cells. Moreover, the antigen-coupled PC able to trigger the suppressor cells showed the presence of the autoantigen of RAG on their surface. The role of the antigen presenting cells in the induction of MRAG-specific inducer-phase suppressor cells is discussed.

Potentiation of autoimmune response in rats infected with Toxoplasma gondii. Inhibition of suppressor system and impairment of thymic cellular populations.

In the present work we studied the influence that an infection with Toxoplasma gondii in thymus proximity produces on the suppression of autoimmune response to autoantigen of rat male accessory glands (RAG). The suppression was achieved injecting syngeneic animals with low doses of autoantigen of RAG previous to the immunization with chemically modified rat male accessory glands (MRAG). Rats were infected in thymus proximity with 3 x 10(3) trophozoites of T. gondii before or after to be suppressed. Controls were rats only infected or only suppressed. The delayed hypersensitivity response against MRAG, (DTH test), was significantly potentiated in rats only infected and in the animals suppressed before the infection (p less than 0.001). The suppression was not inhibited in the animals suppressed after infection. The suppression of humoral response against MRAG studied by ELISA and passive hemagglutination test was prevented in rats infected before as well as in rats infected after the induction of suppression (p less than 0.001). Decrease of CD4+ CD8+ and Ox18+ (class I MHC antigen) and increase of CD4+ CD8- and CD4- CD8- thymocytes was observed in the rats where the DTH response was potentiated. These results indicate that the infection with T. gondii in thymus proximity was able to inhibit the suppression of response to autoantigen of RAG producing selective impairment in thymic suppressor influence.

Antigen induced inhibition of autoimmune response to rat male accessory glands: role of thymocytes on the efferent phase of the suppression.

In the present study, we report that Cy-sensitive, MRAG-adherent spleen mononuclear (SpM) inductor-phase T suppressor (Ts) cells obtained from rats pretreated with low doses of a purified fraction (FI) of rat male accessory gland antigens (RAG) are mainly OX19+ and W3/25+. Furthermore, thymocytes from rats pretreated with FI of RAG restore the suppression of the autoimmune response to RAG autoantigens in irradiated recipients of SpM inductor-phase Ts cells. In contrast, thymocytes from rats pretreated with rat heart saline extract (unrelated antigen) did not recuperate the suppression of the autoimmune response detected by macrophage migration inhibitory factor (MIF) and delayed-type hypersensitivity. The suppressor thymocytes did not directly exert their inhibitory effect because they were not effective to suppress the autoimmune response to RAG autoantigens when irradiated recipients did not receive SpM inductor-phase Ts cells. The effect of these thymocytes was found in PNA--but not in PNA+ thymic cell population. The perithymic injection of Toxoplasma gondii did block their suppressor activity. The present report clearly shows an active participation of thymus in the efferent phase of the suppressor circuit that controls the autoimmune response to MRAG. The implications of these findings are discussed.

Effect of gangliosides in the autoimmune response induced by liposome-associated antigens.

A model of autoimmunity to rat male accessory glands (RAG) was recently developed by intraperitoneal administration of three doses of native RAG associated with liposomes. In this work we analysed the effects of gangliosides in the cellular response to RAG when they were intraperitoneally administrated prior to the second dose of liposome-associated RAG. Results show that the ganglioside treatment could modify an established DTH response. Also, gangliosides markedly reduced the number of Ia antigen-positive peritoneal exudated cells (PEC). However, they modified neither the processing of liposomes through PEC nor their viability. Moreover, we obtained cellular response by transferring PEC from immunized donors into naive receptors.

Delayed hypersensitivity and lesions following isoimmunization with modified rat male accessory glands: kinetics of induction.

The kinetics of the cellular immune response to rat male accessory glands were studied in Wistar rats isoimmunized with modified rat male accessory glands extract and complete Freund's adjuvant at 0, 30 and 45 days. The animals were divided into seven groups, and each group was sacrificed weekly. One immunization was sufficient for the induction of 2-, 6- and 24-h footpad reactivity. The reaction increased until 21 days post-immunization. After the second injection the reaction decreased and was negative 12 days later. Migration inhibitory factor (MIF) activity monitored by a mixed-direct assay was demonstrated in rats from all groups except in the animals studied at day 42 in which macrophage migration was markedly stimulated. The absence of MIF activity correlated with a lack of delayed type hypersensitivity (DTH) response. The humoral response was studied and detected by passive hemagglutination in a few sera after the first immunization. A second injection was necessary to obtain a more frequent occurrence and higher titres of antibodies. Histological modifications in the target organs started to appear in the group of animals studied at 35 days and were characterized by a mononuclear infiltrate in the prostate, coagulating glands and seminal vesicles. In several cases there was also infiltration of polymorphonuclear cells. Specimens obtained at 35 days showed the most severe lesions.

Specific neonatally-induced tolerance to rat male accessory glands antigens. Transference of specific suppression by spleen mononuclear cells.

The immune response of infant rats was studied following (1) immunization of their mothers with modified rat male accessory glands (MRAG) emulsified in complete Freund's adjuvant (CFA), (5 mg/ml or 25 mg/ml) or with human serum albumin (HSA), (5 mg/ml or 25 mg/ml) and (2) intradermal immunization of the offspring at 21 days of age with 5 mg of MRAG-CFA and 5 mg of HSA-CFA. Antibodies to MRAG or to HSA were observed in the sera obtained 20 days after the birth of the offspring. Delayed hypersensitivity (DTH) against MRAG studied 13 days after immunization was significantly reduced in the male offspring born to mothers immunized with 5 mg of MRAG-CFA compared with that of males born to mothers immunized with the same dose of HSA-CFA (P less than 0.0005). In contrast, when 25 mg of MRAG-CFA were used to immunize the mothers, the lack of DTH response to MRAG was observed in male and female offspring (P less than 0.0005 for both groups). In all cases, the DTH response to HSA was positive. The spleen mononuclear (SpM) cells transferred from rats unresponsive to MRAG to normal rats 24 h before the immunization with MRAG-CFA and HSA-CFA did not suppress the immune response whereas transference of SpM cells from suppressed animals to animals previously immunized depressed the DTH response to MRAG (suppression of the expression). The response to HSA was not affected. We can conclude that the suppression is antigen specific.

Adoptive transfer of suppression of autoimmune response to rat male accessory glands with spleen mononuclear cells from antigen-pretreated rats.

The injection of the spleen mononuclear (SpM) cells, obtained from rats rendered unresponsive to autoantigen of rat male accessory glands (RAG) by pretreatment with low doses of purified fraction of RAG (containing the autoantigen), into normal syngeneic recipients markedly prevented the development of delayed type hypersensitivity (DTH) reaction to the autoantigen (suppression of the induction) (p less than 0.001). The humoral response was not altered. The control animals were rat receptors of spleen mononuclear cells from donor rats pretreated with rat lung saline extract or 0.15 M NaCl. In contrast, the transference of SpM cells from donor rats pretreated with low doses of autoantigen prior to the immunization to rats previously immunized, did not modify the expression of the immune response against the autoantigen when compared with control rats. The suppression of the induction of DTH response was also obtained when prior to the immunization, the recipients received T-cell-enriched SpM cell population from unresponsive animals (p less than 0.001), but not when they were injected with B-cell-enriched SpM cells. These results suggest that suppressor T cells capable of controlling induction of the autoimmune response against RAG autoantigen might be one of the immunoregulatory mechanisms that are activated when soluble autoantigen of RAG enter into circulation.

Antigen-induced inhibition of autoimmune response to rat male accessory glands.

Pretreatment of rats with low doses of purified fraction of rat male accessory glands (containing the autoantigen) markedly reduced the immune response to autoantigen when animals were subsequently challenged with modified rat male accessory glands in complete Freund's adjuvant. The rats pretreated with low doses of antigen prior to immunization showed marked suppression of delayed-type hypersensitivity reaction (P less than 0.001) when compared to control animals (pretreated with rat lung saline extract or 0.15 M NaCl). There was also enhancement of migration of macrophages in test male rats, whereas the migration was inhibited in control male rats (P less than 0.01). The stimulation of migration found in the male rats in which the response was inhibited would suggest the presence of a migration stimulation factor, which is considered a marker of suppressor cell activity. Humoral immunity was also reduced. Pretreatment of rats with low doses of the antigen markedly reduced the immune response, probably because of the induction of suppressor cells.

Potentiation of autoimmune response in rats infected with Toxoplasma gondii.

The influence that an infection with Toxoplasma gondii in thymus proximity produces on the autoimmune response was studied. Rats infected with 3 X 10(3) trophozoites of T. gondii in thymus proximity were immunized with 5 mg/ml of chemically modified rat male accessory glands saline extract (MRAG) and/or human serum albumin (HSA) emulsified in complete Freund's adjuvant (CFA) at 6 days after infection. A second immunization was performed 30 days later. Four experimental groups were made: group 1-rats were immunized with MRAG-CFA and HSA-CFA; group 2-rats were infected and immunized with MRAG-CFA and HSA-CFA; group 3-rats were infected and immunized with MRAG-CFA; group 4-rats were infected and immunized with HSA-CFA. The cellular immune response was evaluated at 15 days after first immunization by delayed type hypersensitivity (DTH) test and the humoral response was studied by passive haemagglutination test at 45 days after first immunization. The results indicate that the cellular and humoral immune response against MRAG were significantly potentiated in infected rats (p less than 0.02, p less than 0.05, respectively). The response to HSA did not show significant differences between the infected and uninfected groups. Concomitantly, the histopathological alterations produced by T. gondii in thymus gland were studied at 6 and 52 days after infection. Cortical depletion and presence of parasites in the thymic cortex were detected in both cases. Involution thymic was demonstrated in infected rats killed at 52 days after infection. The possible participation of the thymus gland in the enhancement of the autoimmune response to MRAG is discussed.

Administration of interferon-g to pregnant rats reverses the depressed adjuvant-induced arthritis of their chronically Trypanosoma cruzi-infected offspring.

We demonstrated that administration of interferon gamma (IFN-gamma) to the inbred "I" strain of pregnant rats conferred partial resistance on their offspring to challenge with Trypanosoma cruzi. We now examine if this intervention also modifies the reportedly immunodepressed cellular responses which occur during chronic infection. Offspring were born to mothers undergoing one of the following procedures during gestation: subcutaneous injections of recombinant rat IFN-gamma, 50,000 IU/rat, five times/week for 3 weeks, which was started on the day of mating (IFN-Mo); infection with 10(6) trypomastigotes of T. cruzi at 7, 14, and 21 days after mating plus IFN-gamma treatment as given to the former group (TcIFN-Mo); the same protocol except that physiological saline was injected instead of IFN-gamma (Te-Mo); injection of physiological saline only (control-Mo). All offspring groups (N = 8-10/group) were infected at weaning and were assessed 90 days later for their adjuvant-induced arthritic response or levels of major T cell subsets in spleen and lymph nodes. TcIFN-Mo and IFN-Mo offspring showed a reestablished arthritic response, which remained within the range seen in controls. Immunolabeling studies on parallel groups of 90-day-infected offspring showed that the inverse CD4/CD8 cell ratio that is usually seen in lymphoid organs from these chronically infected rats (median 0.61) appeared to have recovered in the TcIFN-Mo and IFN-Mo groups (median 1.66 and 1.78, respectively) and was not different from uninfected controls (1.96). These studies indicate that early stimulation with IFN-gamma is able to reverse the immunosuppressive state that is usually present during the chronic period of the experimental infection.

[Regulation of the autoimmune response against antigens of male accessory glands of rats]. / Estudio de la regulación de la respuesta autoinmune contra antígenos de glándulas sexuales accesorias masculinas de rata.

Rats immunized with chemically modified rat male accessory glands (MRAG) elicit organ and species specific autoimmune response. We have developed suppression of autoimmunity to MRAG injecting syngeneic rats, previous to immunization with MRAG-CFA, with low doses of the same antigen. The unresponsiveness was mediated, by inducer phase, cyclophosphamide (Cy)-sensitive, antigen specific, T suppressor lymphocytes and effector phase, Cy and irradiation sensitive T lymphocytes. Moreover, we demonstrated that macrophages could play a role in the induction of these MRAG-specific suppressor T lymphocytes. On the other hand, we studied the influence of an infection with Toxoplasma gondii on rats immunized with MRAG-CFA. The cellular and humoral immune responses to MRAG were selectively potentiated in animals infected in thymus proximity, whereas the infection did not modify the response to an heteroantigen, human serum albumin (HSA). The i.p. infection did not alter the cellular response. The potentiation of cellular autoimmune response was correlated with thymic involution and proliferation of lymphocytes and plasma cells. A decrease of Ox-8, Ox-18 and Ox-17 surface markers in thymic cellular population and an increase of immature thymocytes (PNA+) were observed in these animals in correlation with the blockage of the effector phase of suppressor cell circuit. In another study we found that the male kits born to mothers immunized with 5 mg of MRAG-CFA showed significantly reduced DTH response to MRAG. When the mothers were immunized with 25 mg of MRAG-CFA the lack of DTH response was observed in male and female kits. In all cases, the DTH response to HSA was positive.(ABSTRACT TRUNCATED AT 250 WORDS)

[Aortic insufficiency due to quadricuspid aortic valve]. / Insuficiência aórtica por valva aórtica quadricúspide.

In a 45 year old patient with clinic diagnosis of aortic regurgitation the two-dimensional echocardiography demonstrated a quadricuspid aortic valve and severe aortic regurgitation by Doppler. The quadricuspid aortic valve is a rare pathology, usually not associated with other cardiovascular pathologies and in which there is evolution with aortic regurgitation due to malposition of the four cusps.

Antigen-induced inhibition of autoimmune response to rat male accessory glands: distinct role of I-A and I-E-positive peritoneal cells.

The present report describes the structural and functional characteristics of the population of peritoneal cells (PC) from rats injected intraperitoneally (i.p.) 2 h or 24 h previously with a suppressor dose of a purified fraction (FI) of rat male accessory glands (RAG: FI-PC2h and FI-PC24h, respectively). Both populations of PC showed the presence of the autoantigens of RAG on their membrane. The study of cell surface marker showed increase of OX17 (I-E) in FI-PC2h and OX6 (I-A) in FI-PC24h. I.p. injection of FI-PC2h 10 and 3 days prior to immunization with chemically modified (diazotized arsanilic and sulfanilic acid) RAG (MRAG) in complete Freund's adjuvant induced suppression of the delayed-type hypersensitivity (DTH) response to MRAG, whereas the i.p. injection of FI-PC24h induced potentiation of DTH response to MRAG when compared with controls (animals injected 10 and 3 days prior to immunization with PC from rats injected i.p. with an unrelated antigen). The treatment of FI-PC2h with OX17 and FI-PC24h with OX6 prior to the transfer blocked the suppression and potentiation described above. These findings show that the i.p. injection of an FI of RAG at a suppressor dose induces PC with immunologically opposite characteristics, depending on the time of obtention.

Potentiation of autoimmune response in rats infected with Toxoplasma gondii. Effect of the infection route.

The aim of this report is to describe the influence of the way of infection with 3 X 10(3) trophozoites of Toxoplasma gondii on the auto- and heteroimmune responses of rats immunized with chemically modified rat male accessory glands (MRAG) and human serum albumin (HSA) 6 and 36 days after infection. The delayed hypersensitivity (DTH) response to MRAG was potentiated in rats infected in thymus proximity (p less than 0.02) when compared with rats only immunized. The parasites introduced intraperitoneally did not modify the cellular autoimmune response. The titers of hemagglutinating antibodies to MRAG were increased in animals infected by both ways (p less than 0.05). The response to HSA did not show significant difference between the infected and uninfected rats. Thymic involution and proliferation of lymphocytes and plasma cells were observed at 6 and 52 days post-infection only in rats infected in thymus proximity (p less than 0.05). A correlation between the potentiation of cellular autoimmune response and the injection of parasites in thymus proximity was observed.

Effect of aging on the autoimmune response to rat male accessory glands: deficit of I-E-positive peritoneal cells capable of inducing suppression.

The present report analyzes the ability to induce suppression to rat male accessory gland (RAG) autoantigens and the characteristics of T suppressor (Ts)-inducer peritoneal cells (PC) in old rats which show increased autoimmune responses. The injection of young rats with a purified fraction (FI) of RAG 10 and 3 days prior to immunization with chemically modified RAG (MRAG) markedly reduced the immune response to RAG autoantigens when compared with young rats which had only been immunized (controls), while the pretreatment of old rats did not block the delayed-type hypersensitivity reaction to MRAG when compared with control old rats. The study of cell surface markers on PC from rats injected i.p. 2 h previously with FI of RAG (FI-PC) showed an increase of OX-6 (I-A) and a decrease of OX-17 (I-E) in FI-PC of old rats with respect to FI-PC of young animals, which showed a selective increase of I-E+ Ts-inducer PC. The i.p. injection of FI-PC from old rats into young recipients, 10 and 3 days prior to immunization with MRAG in complete Freund's adjuvant, did not modify the autoimmune response when compared with controls. By contrast, the injection of young and old rats with FI-PC from young animals induced a significant suppression of the autoimmune response. The reduced percentage of I-E+ suppressor-inducer PC provides an explanation for the diminished ability to induce suppression to RAG autoantigens in old rats.