LYTIC ANTIBODIES IN TRYPANOSOMA CRUZI–INFECTED PERSONS WITH

Abstract. An antibody-dependent, complement-mediated lysis test performed with three Chilean trypomastigote strains used as target cells revealed strain dependence in the detection of lytic antibodies in chronic chagasic sera. The highest percentage of lytic sera was observed when MF or V115 strains were used as target cells (90 % and 71%, respectively) in the chronic chagasic group with negative xenodiagnosis results. No significant statistical as-sociation was observed between lytic activity in chronic chagasic sera and the presence or absence of cardiopathy (P. 0.01). Western blot analysis showed that lytic sera recognize different antigens depending on the strain used and nonlytic sera had a weaker capacity to detect them. Various antibodies against Trypanosoma cruzi elicited by an active infection may have different functional activities. The lytic function that these antibodies can perform during the course of infection with T. cruzi and what relationship they may have with the level of circulating parasites is the subject of this report. Antibodies that bind to live trypomas-tigote forms and lyse them in conjunction with complement in an in vitro reaction have been linked to active infection. These lytic antibodies, detected by the complement-mediate