HC effect on apoptosis and proliferation of IL-15–activated CD56⁺CD3^– and CD56⁺CD3⁺ cells. (A) Total CD56⁺ cells were cultured with IL-15 in the absence or presence of 10^–4 M HC for 7 days and analyzed by FACS, on CD3^– and CD3⁺ gated cells, for 7AAD (dead cells) and annexin V (apoptotic or undergoing apoptosis cells) staining. Results from one representative donor of 3 tested are shown. Numbers in the quadrants represent percentage of positive cells. (B) Sorted CD56⁺CD3^– and (C) CD56⁺CD3⁺ cells were cultured with IL-15 for a period of 20 days in the absence (♦) or presence (⋄) of 10^–4 M HC. Proliferation of the 2 populations was estimated by [³H]TdR incorporation at the indicated time points. Results represent mean plus or minus SD of triplicate cultures from 2 different donors.