Heterophil nature of EVI antibody in Trypanosoma cruzi infection.

Previous findings implying the autoreactive capability of circulating complement-fixing (EVI) antibodies in patients with Chagas' disease (American trypanosomiasis), under both in vitro and in vivo conditions have been irreproducible. The presence of the tissue antigens involved in the reactivity with EVI antibodies is exclusively confined to nonhuman substrates, suggesting the heterophil nature of these antibodies which, on the other hand, have also been described in human sera collected in areas free from Chagas' disease. This would preclude any direct pathogenic effect of EVI antibodies when present in the circulation, though they may be useful immunological markers of unsuspected Trypanosoma cruzi infection in endemic areas.