Effect of NK cell depletion on KM871-mediated ADCC. Freshly purified PBMCs (Panels A and B; 23.9% CD3-/CD56+/CD16+) and NK cell-depleted PBMCs (Panels C and D; 6.49% CD3-/CD56+/CD16+) were cultured for 7 days with the cytokines IL-2 (10 ng/ml), IL-12 (100 ng/ml), or media alone (control). ADCC activities were determined on days 1 (Panels A and C) and 7 (Panels B and D) at an E:T ratio of 25:1 and with 1 µg/ml KM871 mAb (open bars). Control isotype-matched mAb (//) and medium only (\\) were included. The data, expressed as the mean % cytotoxicity of triplicate samples with error bars denoting standard deviation, is representative of 2 experiments.