DISTRIBUTION OF ALPHA-GALACTOSYL-CONTAINING EPITOPES ON TRYPANOSOMA-CRUZI TRYPOMASTIGOTE AND AMASTIGOTE FORMS FROM INFECTED VERO CELLS DETECTED BY CHAGASIC ANTIBODIES

Reactivity of different Trypanosoma cruzi developmental forms with pur ified Chagasic anti-alpha-galactosyl antibodies (anti-Gal) was studied using epimastigotes from axenic cultures, trypomastigotes and amastig otes from infected Vero cell cultures, and an immunogold labeling meth od as observed by electron microscopy. Epimastigotes were poorly label ed, whereas extracellular trypomastigotes and amastigotes bound hetero geneously to the antibody with many cells being intensely labeled at t he cell surface, including the membrane lining the cell body, the flag ellum and the flagellar pocket. Parasites with poor labeling at the ce ll surface generally had several gold particles within the cell, mostl y in cytoplasmic vacuoles. The Golgi complex of trypomastigotes was st rongly labeled. Intracellular parasites were labeled at the parasite c ell surface or within vacuolar structures. The expression in T. cruzi- infected Vero cells of alpha-galactosyl antigenic structures acquired from the parasite was shown by moderate labeling viith Chagasic anti-G al of the membrane lining parasite-free outward cell projections. The reactivity with purified anti-Gal from healthy individuals at the same concentrations of Chagasic anti-Gal was poor, with gold particles app earing in the nucleus and cytoplasm but not at the cell surface. It pa ralleled the labeling with Bandeireae simplicifolia IB-3 lectin. The r esults provide a basis for autoimmune reactions involving anti-Gal fro m chronic Chagasic patients.