FTI treatment suppresses T-cell lineage–specific cytokine production. Th1 (A) and Th2 (B) T cells were preincubated with varying concentrations (0-10 μM) of FTI CP 390392 for 24 hours followed by stimulation with beads coated with anti-CD3 (2C11, 1 μg/mL) plus anti-CD28 (PV1, 1 μg/mL) antibodies or PMA/ionomycin. Cell activation took place in the presence of indicated concentrations of FTI during the whole culture period. After an additional 18 hours, culture supernatants were analyzed by ELISA for lineage-specific cytokine content (IL-2, IL-4, IL-5, IFN-γ). Stimulations at distinct concentrations were performed in triplicate. Error bars are SD. Cytokine levels were undetectable in the absence of stimulation (data not shown).