Influence of parasite presence on the immunologic profile of peripheral blood mononuclear cells from chagasic patients after specific drug therapy

The aim of this study is to evaluate the effects of parasite clearance on the immunological profile of peripheral blood mononuclear cells (PBMC) from chagasic patients submitted to specific drug therapy. PBMC were examined by flow cytometry and proliferative responsiveness to Trypanosoma cruzi-related stimuli. Three groups of patients were studied: not treated (NT), treated not cured (TNC) and cured (C). All data were compared to values from uninfected individuals (NI). NT displayed a lower percentage of CD3(+) cells as compared to NI, while TNC and C had mean values that were between those from NI and NT. Infected patients had double the percent of CD3(+) HLA-DR(+) cells, independent of the efficacy of the treatment. Thus, absence of circulating parasites did not reduce T cell activation in Chagas' disease. NT displayed a higher percentage of CD5(+) B cells as compared to NI, while TNC and C had mean values between those from NI and NT. In contrast to the phenotypic data, the in vitro mean proliferative responses to parasite-related stimuli of PBMC from C were reduced to the low mean levels observed in NI. These striking differences were statistically different from the high responses seen in NT and TNC. Our data suggest that proliferative responses of PBMC from C reflect immunological changes due elimination of parasite. However, successful treatment did not alter the levels of peripheral T cell activation.