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Biomedical subjects

C M Riera

Publications and source records attributed to C M Riera.

At least 73 records · Page 4Linked to original sources
PubMed1986

Experimental coccidioidomycosis: effects of cyclophosphamide in immunologic responses.

Rats were infected with Coccidioides immitis and injected with cyclophosphamide three days pre or post infection. Administration of the drug before the infection caused enhancement of DTH response and decrease of the colony forming units (CFU). Conversely, injection of the drug three days post infection produced contrary effects, indicating that a normal T-cell function is essential as a defense mechanism in C. immitis infection.

Agglutination Tests↗
PubMed1986

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.

Animals↗
PubMed1986

Characterization of an antigen from rat male accessory glands.

An isolated soluble antigen involved in the autoimmune response against rat male accessory glands migrated as a double band when it was submitted to analytical disc polyacrylamide gel electrophoresis and as a homogeneous molecular species in SDS electrophoresis. The purified antigen had a molecular weight of approximately 78 K by SDS electrophoresis and 80 K by gel filtration chromatography. The antigen was identified as a protein and displays androgen dependency. The purified fraction was pathogenically active in microgram doses and induced humoral and delayed-type hypersensitivity responses. Besides, lesions were observed in the target organ. The cellular infiltration was located in prostate glands according to the localization of antigen by immunofluorescence findings.

Age Factors↗
PubMed1986

Humoral autoimmune response to rat male accessory glands. Comparative specificity studies of auto and heteroantibodies.

A comparison of specific antibodies induced by a saline extract of chemically modified rat male accessory glands (MRAG) in isologous (male and female rats) and heterologous animals (rabbits and a goat) was made. This study was focused on the specificity of the antibodies confronted with saline extract of rat male accessory glands (RAG), their Sephadex G-100 fractions and autoantigen fragments. Specificity studies with Sephadex G-100 fractions of RAG showed that whereas in male rats only the antibodies reactive with Fraction 1 containing autoantigens were detected, one additional population of antibody with different specificity was revealed in female sera. In contrast, antibodies against several other macromolecules were present in heterologous sera. When analyzed for the serum specificity against three enzymatic fragments of autoantigen, the main specificities of male and female sera were different.

Animals↗
PubMed1985

Secretory IgA and secretory component in women affected by recidivant vaginal candidiasis.

Local immunity was evaluated in 47 patients affected by recidivant vaginal candidiasis and 33 control women. IgG, IgA, IgM and secretory component (SC) were determined by single radial immunodiffusion in samples of cervicovaginal secretion. IgG in dosable levels was detected in 17/47 samples (36.2%) and IgA in 15/47 patients (31.9%) whereas in the controls, the incidence was 31/33 (93.9%) for IgG and 24/33 (72.7%) for IgA. The difference was significative (P less than 0.001) for both immunoglobulins. Significant differences were not obtained for IgM. The SC was detected in 4/47 cervicovaginal secretions of patients affected by candidiasis (8.5%) whereas in the control samples the incidence was 21/33 (63.6%) (P less than 0.001). In only 2/15 patients with dosable levels of IgA (13%) the secretory nature of this immunoglobulin could be shown by its reaction with anti-SC serum. In the control group, secretory IgA was detected in 19/24 cases (79%) (P less than 0.001). Serum immunoglobulins levels were normal. The lack of secretory IgA and SC in the secretion could be related to the adherence capacity of the Candida albicans to epithelial cells.

Adhesiveness↗
PubMed1985

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.

Animals↗
PubMed1984

Effect of cyclophosphamide on rats experimentally infected with Cryptococcus neoformans.

This study was undertaken to establish the function of T-lymphocytes in protective immunity against a cryptococcal infection in animals treated with Cyclophosphamide (Cy) pre or post infection and to determine how they relate to the progression of the disease. Inbred Suquia rats were infected either intranasally (i.n.) or intraperitoneally (i.p.) with 10(5) viable Cryptococcus neoformans cells. The infected rats were divided in three groups. One of the groups (group I) was utilized as a control. The second group (group II) was treated with Cy 3 days before the infection. The third group (group III) was treated with Cy 3 days after the infection. At approximately 22 days post infection, C. neoformans growth in selected organs of all animals were determined. In addition, humoral and delayed-type hypersensitivity (DTH) response were assayed in the rats. When the Cy was applied after the infection the DTH was significantly diminished and inverse to the colony forming unit (CFU) which increased leading to the animals death. On the other hand, injection of the drug 3 days before infection did not modify the response, that was comparable in both treated and the control animals. In this study it were found haemagglutinating antibodies in sera from i.n. and i.p. infected rats although at minimal levels and were not present in all animals. The results show that with a low T-cell function induced as a consequence of injecting Cy after the infection, rats did not develop a normal DTH response to cryptococcal infections and were not able to control a cryptococcal infection as well as animals with normal T-cell function.

Animals↗
PubMed1984

Study of HLA system in a Mataco population: a geographically isolated American Indian tribe.

A search for antigens of the HLA system has been carried out in 53 Mataco Indians of Argentina living in a geographically isolated area in the northeast of the country. Samples were mostly collected from adults of both sexes who were not directly related. Lymphocyte typing was performed using the microcytotoxicity technique of NIH. 118 sera specific for 15 antigens of the first HLA locus, 22 antigens of the second and 6 of the third were used. The most frequently found alleles were HLA-A28, Aw31 and A2 for the first locus; B15 and B40 for the second; and Cw3 and Cw4 for the third. In addition to previously published investigations on South American Indians, our typing work shows a remarkable homogeneous gene pool and a restricted range of polymorphism; therefore, a further set of haplotypes rendered us also restricted. The most frequent haplotypes that showed a significant statistical linkage disequilibrium were: A2-Cw4, A28-Bx, A2-Cw3, Aw31-Bw16, Aw24-Cw3, B15-Cw3, Bw16-Cw3 and A28-B5. Some of these haplotypes have also been found in other indian populations.

Adult↗
PubMed1984

Humoral autoimmune response to rat male accessory glands. Effect of castration on the humoral response.

The ability to induce antibodies to rat male accessory glands in male and female rats was demonstrated, but a higher response with wider specificity was revealed in female animals. In order to investigate whether this different response may be influenced by sexual hormones we castrated male and female rats at 4 or 30 days after birth. After that we studied the course and specificity of their humoral response to male accessory glands comparing them with that of sham-operated, sex-matched, littermate controls. Orchidectomy in male or oophorectomy in female rats changed neither the course nor specificity of humoral immune response. We conclude, therefore, that hormonal factors do not play any important role in the experimental model under study.

Animals↗
PubMed1984

Study of autoimmune response to rat male accessory glands in rats born to immune mothers.

Passive transfer of antibody across the placenta or in milk has been thought to have a regulatory effect on the immune responsiveness of young animals. The effect of maternal antibody against rat male accessory glands (MRAG) on the systemic autoimmune responses of rat kits was studied. Serum obtained during the nursing period from female rats immunized with 5 mg/0.5 ml of MRAG or human serum albumin (HSA) emulsified in Freund's complete adjuvant before and during pregnancy contained anti-MRAG or anti-HSA, respectively. Kits born to MRAG-immunized dams were intradermally immunized with 5 mg/0.5 ml of MRAG-CFA at 21 and 51 days of age. Control kits from dams immunized with 5 mg/0.5 ml of human serum albumin emulsified in Freund's complete adjuvant (HSA-FCA) were similarly immunized with MRAG-FCA. Delayed-type hypersensitivity (DTH) studied 13 days after immunization with MRAG given at 21 days of age was significantly reduced only in the male kits born to MRAG-immunized dams compared with that of male kits from HSA-immunized dams (P less than 0.005). This hyporesponsiveness was not found in female kits from dams immunized with MRAG-FCA. The titre of circulating anti-MRAG studied at 65 days of age in kits born to MRAG-immunized dams approximated that in control kits. Antibodies against MRAG passively acquired from MRAG-immunized mothers did not alter the humoral autoimmune response of their kits.

Animals↗
PubMed1983

Experimental cryptococcosis in guinea pigs.

A guinea pig model was used to evaluate immune response to Cryptococcus neoformans. This model shared characteristics with cryptococcosis in humans. Twenty five guinea pigs injected intraperitoneally with 10(7) viable C. neoformans cells developed disseminated disease. Forty days after infection all guinea pigs were killed and autopsy performed. C. neoformans growth in the lungs, brains, livers and spleen of the infected animals were determined. Furthermore, the immune response was characterized by moderate degree of delayed-type hypersensitivity and humoral response. In some organs was observed neutrophil and lymphocyte infiltration with presence of cryptococci cells. The infiltration observed in the organs was probably a consequence of an immune reaction.

Animals↗
PubMed1983

Evaluation of the immunosuppression in an experimental model of autoimmunity: suppressor activity of spleen cells from cyclophosphamide-treated rats.

Rats immunized with chemically modified rat male accessory glands (MRAG) and injected 3 days later with cyclophosphamide (CY) were unable to develop humoral and cellular immune response to the autoantigen of MRAG. The present report demonstrates that the spleen mononuclear (SpM) cells transference from rats injected with CY 3 days after the antigen to normal male or female syngeneic animals before immunization with MRAG did not suppress the immune response to this antigen, whereas the transference of SpM cells from suppressed animals to animals previously immunized, depressed the delayed type hypersensitivity (DTH) response against MRAG (suppression of the expression) only in male rats. Similar results were obtained by transference of purified T cells. SpM cells did not suppress an established humoral immune response induced in male or female rats. The results suggest that non-adherent cells present in the spleen of male suppressed rats might be one of the responsible mechanisms for suppression of the efferent phase of the cellular autoimmune response to MRAG.

Animals↗
PubMed1983

The effect of cyclophosphamide on autoimmune response to rats immunized with modified accessory glands.

It was found that the organ specific hemagglutinating autoantibodies to rat male accessory glands can be suppressed by the injection of a single dose of cyclophosphamide applied 3 days after the first immunization. On the other hand, injection of the drug 3 days before immunization did not modify the response, that is, there were comparable incidence and titers in both treated and the control animals. Cyclophosphamide did not appear to act on the homocytotropic antibodies. These results indicate that cyclophosphamide acts only when it is administered after antigenic stimulation, to suppress hemagglutinating antibodies production.

Animals↗
PubMed1983

Isolation of rat male accessory glands autoantigens by affinity chromatography.

The autoantigens of rat male accessory glands were isolated by a short procedure which involved 1) immunization of rats with chemically modified rat male accessory glands' saline extract; 2) purification of immunoglobulin G (IgG) from the autoantisera by chromatography on DEAE-Sephadex A-50;3) coupling of rat IgG anti-rat male accessory glands with 4-B activated Sepharose; 4) addition of rat male accessory glands' saline extract and removal of autoantigens by glycine-HCl, pH 2.9. The purity of the eluted autoantigens was determined by polyacrylamide disc gel electrophoresis (PAGE). These components retained their immunologic activity as demonstrated by inhibition of tanned cell hemagglutination and double immunodiffusion gel precipitation.

Animals↗
PubMed1983

Specific suppression of humoral and delayed hypersensitivity responses by cyclophosphamide in an experimental model of autoimmunity.

The aim of this report is to investigate the effect of cyclophosphamide (CY) in an experimental model of autoimmunity to rat male accessory glands. The results indicated that 100 mg/kg of this drug suppressed humoral immune response that persisted for at least 45 days when administered 3 days after the first immunization of rats with modified rat male accessory glands (MRAG) in complete Freund's adjuvant (CFA). Administration of the drug 3 days before ID injection of antigen caused a shorter suppression of antibody formation. Delayed type hypersensitivity (DTH) studied 13 days after the first immunization was suppressed only in the animals that were administered CY after the antigen. The specificity of the immunosuppression was studied in rats treated with CY after the first immunization with MRAG using aggregated human gamma-globulin (AHGG) as an unrelated antigen. The studies demonstrated significant suppression of DTH (p less than 0.005) and humoral immunity only against MRAG. On the contrary, the response to AHGG was not significantly modified.

Animals↗
PubMed1980

Detection of autoimmune response to rabbit epididymal and seminal spermatozoa.

Conventional and anaphylactic autoantibodies to rabbit epididymal and seminal spermatozoa were detected in sera of rabbits autoimmunized by several procedures. Antibodies against epididymal spermatozoa were found in 85% of rabbits showing lesions of varying degrees in testes. When the comparison was made with antibodies to antigens of spermatozoa from semen, the correlation was markedly lower. The data prove the importance of a proper selection of the antigenic material when looking for antibodies to spermatozoa in studies of autoimmunity and fertility.

Animals↗