Gene transcription is required for the induction of natural cytotoxicity and CD38-dependent lysis. PBLs from 2 separate donors were activated for 3.5 days in medium containing 200 U/mL IL-2 and the indicated concentrations of actinomycin D. Cells were then tested for the ability to mediate natural cytotoxicity (No Ab) or cytotoxicity directed by anti-CD38 or anti-CD16 MoAbs.