Specific ADCC mediated by 1 µg/ml KM871. Specific ADCC was determined by subtracting the background LAK cytotoxicity from that observed with 1 µg/ml KM871. The KM871-specific release of ⁵¹Cr effected by PBMCs precultured with the cytokines IL-2 (10 ng/ml), IL-12 (100 ng/ml) or GM-CSF (500 ng/ml) individually or in combination is presented for days 1, 3, 5 and 10 as the mean percent cytotoxicity, with standard errors, for triplicate samples.