Induction of macrophage TNF-α by cytokine-stimulated T cells (Tck) is differentially regulated by PI3K and p70S6K. Tck were added in co-culture with M-CSF-primed macrophages at a T : macrophage ratio of 5:1. Macrophages were pretreated for 1 hour with indicated concentration of PI3K inhibitors LY294002 (a) or wortmannin (b) or with the p70S6K inhibitor rapamycin (c) before co-culture for 24 hours at 37°C/5% CO2, after which supernatants were harvested and stored at -20°C until ELISA. Bars show mean TNF-α in triplicate culture supernatants ± SD, for a representative of N = 3 replicate experiments. M-CSF = macrophage-colony-stimulating factor; p70S6K = p70 S6-kinase; PI3K = phosphatidylinositol 3-kinase; T:M = ratio of Tck to M-CSF-primed macrophages; TNF = tumour necrosis factor. *P < 0.05, **P < 0.01, ***P < 0.001.