HDAC inhibition interferes with IL-2 expression blockade in anergic Th1 cells. (A) Th1 cells were treated with ionomycin in the presence or absence of TSA. Untreated and TSA-treated cells were used as controls. After a 16-hour treatment, cells were allowed to rest for 4 hours and then restimulated with anti-CD3 and anti-CD28 (right) or PMA and ionomycin (left). IL-2 production was determined by ELISA. Bars show mean + SEM of 3 experiments. (B) After a 16-hour treatment with ionomycin, Th1 cells were allowed to rest for 4 hours and then restimulated with anti-CD3 and anti-CD28 in the presence or absence of TSA. IL-2 production was measured by ELISA. Graphs show either IL-2 values from one representative experiment (mean + SEM from 3 different samples per condition; left) or IL-2 production relative to control stimulated Th1 cells from 4 independent experiments (mean + SEM; right).