FIG. 6.

Large CD4⁺ T lymphocytes are the main source of IFN-γ in PBMC from patients with Chagas' disease. Representative histograms show frequencies of various T-cell populations in PBMC from one out of three Chagas' disease patients after 20 h of culture with either PFR, EPI-Ag, or medium alone. Frequencies of cells expressing the indicated surface markers and intracellular cytokines were determined by use of antibodies directly conjugated with either FITC (x axis) or PE (y axis) as described in Materials and Methods. Top left histogram represents forward- and side-scatter gates for R1 (small lymphocytes) and R2 (large lymphocytes).