Cytolysis mediated by cytokine-activated NK cells and inhibition by concanamycin A. (A) Lymphoma cells were coincubated with cytokine-activated NK cells at various effector-target ratios for 4 hours. Means and SEM of 3 experiments are shown. (B) Lymphoma cells were coincubated with cytokine-activated NK cells (solid lines) and resting NK cells (broken lines; experiments with SUP M2 and K562 only) for 4 hours without (♦) or with (⋄) 50 nM concanamycin A. One out of 2 experiments is shown. Concordant results were obtained in both experiments. Specific cytolysis was determined by propidium iodide.