Induction of IFN-γ secretion in human resting Th cells by inflammatory cytokines. (A) Th cells were stimulated with the cytokine cocktail (IL-1β, IL-6, IL-7, IL-8, IL-12, IL-15, IL-17, IL-18, TNF-α, and MIP-1α). After 72 hours, supernatants were analyzed for secreted IL-2, IL-4, IL-5, IL-10, and IFN-γ by cytometric bead enzyme-linked immunosorbent assay. (B-D) Th cells were stimulated as indicated. Frequencies of (B) IFN-γ–, (C) IFN-γ– and TNF-α–, or (D) IFN-γ– and IL-17–expressing cells were analyzed at different time points intracellularly by FACS. (E) Th cells were stimulated for 36 hours with different cytokines or for 12 hours with αCD3 + αCD28 and assessed intracellularly for IFN-γ and TNF-α as before. One experiment of 3 (A,D) or 5 (B,C,E) is shown.