Fig. 3. : immunophenotypic profile and cytokine patterns [interferon (INF)-γ and interleukin (IL)-4] of CD4+ and CD8+ T-lymphocyte present in peripheral blood before infection (0), nine, 60, 90 and 240 days after infection with Y strain (Y) or Colombian strain (Col) of Trypanosoma cruzi. T-cells subsets were identified by flow cytometric immunostaining as described in Materials and Methods. Data were expressed as the index, i.e., the mean percentage of positive cells of cultures stimulated/mean percentage of positive cells of unstimulated cultures, within gated lymphocytes. A-D: index of cytokine production by CD4+ or CD8+ in culture stimulated with epimastigote antigens of the Y strain; E-H: index of cytokine production by CD4+ or CD8+ in culture stimulated with epimastigote antigens of the Col strain. The results are expressed as index ± standard error. Significant differences at p < 0.05 are indicated by letters a, b and c for comparisons with days 9, 60 and 90, respectively. #: differences between the non-infected group (NI) and infected groups (Y or Col).