ADCC activity of chCLL-1 and fusion proteins. MoAb or fusion protein (1 μg/mL) was cultured with ARH-77 human myeloma target cells and human mononuclear effector cells at varying effector:target cell ratios as indicated. (A) Comparison between ADCC mediated by muLym-2 and chCLL-1. (B) Comparison between ADCC mediated by chCLL-1 and chCLL-1/IL-2. (C) Comparison between ADCC mediated by chCLL-1 and chCLL-1/GM-CSF. Specific lysis with the isotype-matched negative control (chTNT-1) was <5% (data not shown). Expressed as mean ± SD. At each effector:target cell ratio, the difference between pairs is significant (P < .001).