FIG. 3.

IFN-γ and IL-4 production by peripheral T cells. Peripheral blood mononuclear cells were isolated from heparinized blood of a healthy donor by using a Ficoll-Hypaque density gradient. The cells were cultured in Click’s medium for two weeks in the presence of recombinant human IL-2 (10 U/ml) and recombinant human IL-4 (20 U/ml). Thereafter, the cells were left untreated (left) or stimulated (right), and intracellular staining of CD4, IFN-γ, and IL-4 was performed as described in the text. Gating was restricted to CD4⁺ cells according to staining with anti-CD4 CyChrome. x axes, staining with FITC-conjugated anti-IFN-γ Ab; y axes, staining with PE-conjugated anti-IL-4 Ab.