Cellular immunity in Chagas' disease patients. Lymphoproliferative response to subcellular fractions of Trypanosoma cruzi.

The ability of peripheral mononuclear cells from Chagas' disease patients (CDP) to generate specific proliferative responses in vitro to whole homogenate (WH) and subcellular fractions of T. cruzi was investigated. Flagellar (F), microsomal (Mc) and cell sap (CS) fractions were isolated from a WH obtained by disruption by pressure-depressure. Parasite-free human peripheral mononuclear cells were isolated by centrifugation of leukocyte-rich plasma over discontinuous gradients of Ficoll-Hypaque and cultured for 6 days in the presence of the different fractions of T. cruzi. Eighty-six percent (54/63) of the CDP showed good capacity to respond to at least one of the fractions assayed while only 18% (4/22) of the controls reacted. The Mc fraction showed the best specificity as well as the maximal stimulating effect in CDP (37/55 vs 0/18 in controls) while WH (62% vs 10%), F (54% vs 16%) and CS (52% vs 6%) showed a lesser antigenic capacity. These results suggest that recognition mechanisms and proliferative responses are functional in CDP. No correlation was found between the stimulating capacity of fractions in vitro and their immunogenic capacity previously observed in vivo.