Biological activity of chronic phase antibodies eluted from sensitized Trypanosoma cruzi trypomastigotes

Chronic infection with Trypanosoma cruzi induces high levels of antibodies that have lytic and clearance activities on bloodstream trypomastigote forms. These two activities were tested with antibodies eluted from parasites sensitized with serum obtained from mice in the chronic phase of infection. Parasites submitted to treatment for antibody elution were also tested. Our results show that antibodies eluted from the parasites are very efficient to induce lysis but unable to induce clearance. In addition, we observed that after being submitted to treatment for antibody elution the parasites still presented a slower but significant clearance and a high lytic activity. These results allow us to suggest that clearance inducing antibodies are mostly high affinity antibodies that could not be eluted from the parasites in our experimental conditions.