NADPH-oxidase-dependent inhibition of NK-cell cytotoxicity by nonmalignant GR.

One hundred thousand NK cell-enriched lymphocytes were admixed with GR and assayed for cytotoxicity against K562 cells (10⁴cells/well) in a 16-hour assay. The cell cultures were treated with culture medium (control, ○) or fMLF (0.1 μmol/L, ▴), added at 15 minutes after the onset of incubation. Data are cell lysis percent ± SEM of sextuplicate determinations. The inset shows a corresponding experiment in which cells were treated with culture medium (med), histamine (H; 10 μmol/L), or catalase (C; 100 U/mL).