[Autoantibody profile among Kaingang and Guarani tribe Indians in Southern Brazil].

This study investigated the autoantibody profile of 241 blood samples from 176 Kaingang and 65 Guarani Indians from three populations living on the Rio das Cobras and Ivaí reservations, in the state of Paraná, in southern Brazil. The presence of antimitochondrial, anti-smooth muscle, antinuclear, anti-parietal cell, and anti-liver-kidney microsome antibodies was determined by indirect immunofluorescence. These results were compared with samples from 100 healthy Caucasian individuals from the general population of the state. Total positivity was 9% for the indigenous population and 4% for the control population. The prevalence of anti-smooth muscle antibodies was significantly higher among the Guarani and Kaingang individuals from the Rio das Cobras reservation (P = 0.03). It is likely that the increased exposure that these indigenous Brazilians have to infectious diseases that were previously unknown to them comes from more contact with non-native populations, growing acculturation, and cultural practices that include scarification and tattooing. The presence of auto-antibodies in these Brazilian Indians may be related to mechanisms of molecular mimicry with viral or bacterial antigens.