HC does not affect the killing capacity of CD56⁺ cells. Isolated CD56⁺ cells cultured for 20 days with IL-15 in the absence or presence of HC, at concentrations ranging from 10^–8 M to 10^–4 M, were tested for their cytolytic activity against (A) NK-sensitive (K562) and (B) LAK-sensitive (Daudi) targets in a 4-hour chromium release assay at different effector-to-target (E/T) ratios. NK (C) and LAK (D) activities of the cultured cells were tested throughout the whole culture period at the indicated time points (E/T ratio 1:1). Results from 4 (A and B) and 3 (C and D) healthy donors (mean ± SD) are presented.