Role of complement in immune lysis of Trypanosoma cruzi.

Studies were performed on the mechanism of immune lysis of culture forms of Trypanosoma (Schizotrypanum) cruzi. Antibody-mediated lysis is caused by complement, which is activated via the classical pathway. The properdin system is not required. The kinetics of the reaction is similar to that followed by immune lysis of sensitized sheep erythrocytes, as is the concentration of divalent cations required for optimal lysis (0.15 mm Ca(2+) and 0.5 mm Mg(2+)), the occurrence of cell membrane uptake of the complement components C3 and C4, and the development of characteristic ultrastructural modifications on the cell membrane.