Comparative studies on epimastigote and metacyclic stages of Trypanosoma cruzi. II. Selective lysis by rodent sera.

In a series of immunological studies on Trypanosoma cruzi, the lytic titers of epimastigotes and metacyclic trypomastigotes by sera obtained from normal and infected rodents were compared. Lysis of culture forms of T. cruzi by normal mouse or rat serum was restricted to the epimastigote form. Freezing reduced the lytic titers of rodent sera. This serum lytic activity was also depressed during the acute infection phase. Metacyclic trypomastigotes were more resistant than epimastigotes to both nonspecific and specific lysis by sera, However, provided with fresh complement, antisera collected from mice or rats lysed 12-26% of metacyclic trypomastigotes.