[Levels of anti-Gal antibodies in persons infected and non-infected with Trypanosoma cruzi. Probably induced by bacteria and by the parasite].

Antibodies levels against Gal alpha 1,3 Gal epitopes were studied in 407 human sera (92 chagasic and 315 non-chagasic), by means of hemagglutination with rabbit erytrocytes reactivity of serum having high titres of anti-Gal antibodies in presence of Escherichia coli and Serratia marcescens antigen was studied by immunoelectrotransference. Finally, using a purified anti-Gal antibody, Gal alpha 1,3 Gal epitopes were identified in metacyclic forms from 12 high Andean Chilean strains of Trypanosoma cruzi. Among the chagasic sera, it was demonstrated that in 63 (68.5%) were detected antibodies anti-Gal at the same or higher titer than 1:1,600; while i the non chagasic sera only 49 (15.6%) showed and anti-Gal response at similar titers. Immunoelectrotransference showed that the sera of people infected with T. cruzi recognize antibodies present in E. coli and S. marcescens, which reinforces the idea that at least in part, these bacterias would be capable of stimulating these responses. The autoradiographic analysis using purified anti-Gal antibodies, showed differences in the Gal alpha 1,3 Gal epitopes expressed in the different strains of T. cruzi. These results suggest that anti-Gal antibodies could have a real significance on the natural immunity mechanisms and protection of human infection with T. cruzi.