KM871-mediated ADCC activity of PBMCs cultured in the presence of individual cytokines. PBMCs (2.5 x 10⁵/well) were cultured for 1 to 10 days at 37°C with (A) medium alone, (B) 10 ng/ml IL-2, (C) 100 ng/ml IL-12, or (D) 500 ng/ml GM-CSF. ADCC activities were assayed at each time point at an E:T ratio of 25:1 and with 1 µg/ml KM871 mAb (open bars). Control mAb KM966 (//) and medium only (\\) were also included. The data, expressed as the mean % cytotoxicity of triplicate samples with error bars denoting standard deviation, is representative of over 3 experiments conducted.