Biomedical subjects

H M Serra

Publications and source records attributed to H M Serra.

24 records · Page 2Linked to original sources

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

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

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

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↗

PubMedDate not supplied

Seroprevalence of human herpesvirus 6 in Andino Puneños (Argentina).

We carried out a seroepidemiological survey to define the prevalence of human herpesvirus 6 (HHV6) infection in an aboriginal population (Andino Puneños) from a remote region in north-west Argentina. Antibodies against HHV6 (total IgG and the 4 subclasses of IgG) were studied in 84 serum samples (collected in 1995 and stored at -70 degrees C), using core blood mononuclear cells infected with HHV6 in an immunofluorescence assay. Of the 84 samples, 70 (83%; 95% confidence interval, 75-91%) exhibited IgG antibodies against HHV6. No significant differences in the frequency of humoral immunity were found among the 4 age-groups studied (mean ages 13, 31, 47 and 70 years) namely, 75%, 89.7%, 79.2% and 100%, respectively. HHV6-specific IgG1 was found in all the positive serum samples tested but none of them contained specific IgG2, IgG3 and IgG4. These results confirmed a high rate of infection with HHV6 within this aboriginal group in Argentina and an IgG1 anti-HHV6 activity compatible with a maintenance of immunity.

Adolescent↗