CD56⁺CD3⁺ cells can kill NK-sensitive and NK-insensitive targets. The ability of CD8⁺ (▵), CD56⁺CD3^- (□) and CD56⁺CD3⁺ (○) cells to kill NK-resistant Raji cells (A) and NK-sensitive U937 cells (B) was assessed at different E/T ratios. Cells were incubated together for 4 hours, and apoptotic cells were identified by Annexin V-PE and 7-Amino-Actinomycin D staining after gating the targets by forward and side scatter. Data shown are the mean ± SEM of duplicates from 2 different donors.