Myeloma patient NK cell function cannot be enhanced by ex vivo treatment with lenalidomide. (A) Patient PBMCs (n = 4) were collected at both baseline and cycle 6 and treated with dexamethasone, lenalidomide, both lenalidomide and dexamethasone, dexamethasone with high-dose IL-2 (500 U/mL), or no drugs. The PBMCs were used as effectors at 50:1 target ratio against K562 as target cells, and (B) U266 targets. (C) To assess why lenalidomide could not enhance NK function, supernatants from the experiments described above were collected and assessed for IL-2 by cytokine bead array. Data are pooled from 4 separate experiments.