IL-2–induced IL-5 production and proliferation of T-cell clones were suppressed by dexamethasone. (A) A total of 10⁵ T-cell clones ([○] HK5; [▵] YA5; [□] HK2; [•] YA8) were cultured in 96-well round-bottom culture plates with human rIL-2 (100 U/mL). Designated concentrations of dexamethasone were included from the start of some cultures. Culture supernatants were harvested after 24 hours and assayed for IL-5 by a specific ELISA. Data are expressed as the mean of triplicate cultures ± SEM. IL-5 production in the unstimulated cultures was always below the detection limit of the ELISA system (<1 pg/mL). (B) For proliferation assays, cells were cultured for 72 hours. ³H-Thymidine (0.5 μCi/well) was pulsed for the last 16 hours. Data are expressed as the mean of triplicate cultures ± SEM. ³H-Thymidine incorporation of unstimulated HK5, YA5, HK2, and YA8 cells was 362 ± 154, 526 ± 193, 759 ± 227, and 668 ± 149, respectively.