Cytolysis mediated by resting allogeneic NK cells and degranulation of NK cells. (A) Lymphoma cells were coincubated with resting NK cells for 4 hours. Specific cytolysis was determined by propidium iodide assay. Means and SEM of 3 experiments are shown. (B) Degranulation of resting NK cells was determined by CD107a staining after coincubation with lymphoma cells for 5 hours. The degranulation of NK cells was performed with NK cells of the same donor as in the cytolysis assays shown in panel A. Means and SEM for 3 experiments are shown.