Antibodies from Chagas patients serum bind to the gut epithelial cell surface of Triatoma infestans.

Serum of chagasic patients with a high title of specific antibodies against T. cruzi antigens, binds epitopes in the midgut and hindgut of the insect vector Triatoma infestans free of parasites. These antigens were recognized at ultrastructural level by immunocytochemistry with serum of chagasic patients as first antibody and protein "A"-gold as marker. Controls with normal human serum were negative. The positive reaction occurs principally in the apical epithelial portion (microvilli and peritrophic membrane) of the midgut and in the cuticular layer and adjacent cytoplasm of the hindgut. In vectors infected with trypanosomes, the antigen-antibody reaction occurs similarly in the epithelium and also in the trypanosomes present in the lumen. These results suggest that there are antigenic factors in the vector gut that are incorporated by the parasite and are recognized by the immunitary system of the human patient with production of specific antibodies.