Trypanosoma cruzi: Antibody-induced mobility of surface antigens

Antibody induces mobility of surface antigens of live blood forms of Trypanosoma cruzi when these cells are incubated with human or animal antisera. Parasites of one strain (Y) showed aggregation of surface antigens to form an anterior or more frequently a posterior cap. The proportion of cap forming trypomastigotes increased with time and was dependent on temperature and amount of antiserum. Cap formation was inhibited by sodium azide or iodoacetamide. Crosslinking of surface antigens by antibodies causing agglutination of trypomastigotes decreased antigenic mobility and capping. Capping was not affected by treatment of the parasites with colchicine or cytochalasin B. Antigen mobility was not related to the presence of antibodies against parasite and host tissue cross-reacting antigens. Aggregation of surface membrane antigens was also observed in parasites which survive after immune lysis. Results of light and electron microscopic studies suggested that at least part of the aggregated antigens was eliminated from the trypomastigote's surface. Cap formation was strain and stage dependent. It was not observed when Y-strain epimastigotes were used and it occurred less frequently in CL than in Y-strain trypomastigotes.