Lenalidomide modulates cytokine production by T cells and NKT cells in vitro. Peripheral blood mononuclear cells (PBMCs) from healthy donors were stimulated with 100 ng/ml αGalCer and cultured for 7 days with 1 μM lenalidomide or an equivalent volume of vehicle. Cells were then restimulated with phorbol 12-myristate 13-acetate (PMA) and ionomycin for 4 h and stained for intracellular interferon-γ (IFN-γ), tumor necrosis factor (TNF) and interleukin (IL)-4 for analysis by fluorescence-activated cell sorting (FACS). Graphs depict the paired comparison of the proportion of T cells (a–c) or NKT cells (d–f) producing IFN-γ (T-cell P-value<0.01; NKT cell P-value<0.0001, Wilcoxon test), TNF (T-cell P-value<0.005; NKT cell P-value<0.0001, Wilcoxon test) and IL-4 (T-cell P-value<0.01; NKT cell P-value<0.001, Wilcoxon test) from cultures supplemented with lenalidomide or vehicle. Each pair of symbols represents the outcomes of the two culture conditions for each healthy donor (20 in total). Pooled data from the individual samples are shown in bar graphs. Error bars represent the standard error of the mean. Samples were analyzed over five independent experiments.