Fatores imunogenéticos de risco na infecção por toxoplasma Gondii em doadores de sangue

Abstract

The etiological agent of toxoplasmosis, Toxoplasma gondii, is an obligatory intracellular protozoan with a wide geographic distribution and a high prevalence worldwide that uses the human gastrointestinal tract as one of the routes of infection. In this tract the ABH glycoconjugates of the ABO System are also expressed. The highly polymorphic HLA genes control the adaptive immune responses against T. gondii. Associations between ABH glycoconjugates and HLA alleles raise attention to their potential influences on susceptibility and resistance to human toxoplasmosis. Aim. To investigate ABH glycoconjugates and HLA class I and II alleles as host immunogenic factors that contribute to the risk of T. gondii infection in blood donors. Material and Method. A total of 1,729 blood donors, both genders, and elegible for donation from Hemocentro of São José do Rio Preto, were selected. Blood donors were classified according to reactive and non-reagent serology for anti-T.gondii antibodies of the classes (IgG and IgM) by the (ELISA) method. A subgroup with 348 donors was evaluated for HLA class I and II alleles. The ABO phenotypes were performed by hemagglutination method in tubes and HLA class I (HLA-A and HLA-B) and class II (HLA-DRB1) genotyping was performed by the PCR-SSOP method (Luminex®). The t-test and the chi-square test were used to compare the proportions (p≤0.05). Harlequin software (3.11) was used to analyze HLA alleles and haplotypes. Odds Ratio values and the 95% confidence interval were also calculated. Results. Out of the 1,729 donors, 835 (48.3%) were reagents and 894 (51.7%) were non-reactive for anti-T gondii antibodies. No statistically significant differences were observed in the prevalence of infection between genders as well as among the four ABO phenotypes. The frequencies of the HLA class I and II alleles also did not differ for reactive and non-reactive serology. No statistically significant differences were found between the frequencies of the HLA-A, HLA-B and HLA-DRB1 alleles in the donor groups with and without infection. The frequencies of the allelic groups were in Hardy-Weinberg equilibrium, and the HLA-DRB1 * 13 allele was not associated with the risk of infection after the Bonferroni correction. The HLA-A * 02_HLA-DRB1 * 13 haplotype was associated with the presence of anti-T gondii antibodies. Conclusions. The frequency of T. gondii infection in blood donors from the northwest region is high, and the ABO phenotypes and HLA class I and II alleles are not risk factors for the acquisition of T. gondii infection alone. However, the haplotype HLA-A * 02_HLA-DRB1 * 13 was shown to be associated with T. gondii infection.