Lenalidomide treatment of B-CLL cells resulted in diminished ADCC mediated by rituximab. (A) ADCC was measured using freshly isolated NK cells from normal volunteers and lenalidomide- (0.5 μM) or vehicle control–treated B-CLL cells at 12.5:1 and 25:1 E/T in the presence or absence of 10 μg/mL rituximab or trastuzumab. Columns, average of triplicate wells, were representative of 5 independent experiments; bars represent SD. The overall lenalidomide- versus vehicle rituximab-mediated ADCC was significantly lower for lenalidomide (P < .05). (B) ADCC was measured using untreated NK and lenalidomide- or vehicle-treated B cells from CLL patients at 12.5:1 and 25:1 E/T in the presence or absence of 10 μg/mL rituximab or trastuzumab. Columns, average of triplicate wells, were representative of 2 independent experiments; bars represent SD (N = 2, P < .05). (C) ADCC was measured using lenalidomide- or vehicle control–treated NK and B cells from CLL patients at 12.5:1 and 25:1 E/T in the presence or absence of 10 μg/mL rituximab or trastuzumab. Columns, average of triplicate wells, were representative of 2 independent experiments; bars represent SD (N = 2, P = .02).