Lenalidomide induces down-regulation of CD20 in CLL B cells. CD19⁺ cells were incubated with lenalidomide (0.5 μM) or vehicle control. (A) CD20 surface expression was analyzed by flow cytometer after 48 hours of treatment. The graphs show fold change in percentage of CD20⁺ cells (left panel) or mean fluorescence intensity (right panel). n = 18; * indicates P < .001; and **P = .001. (B) Results for CD20, CD19, CD5, and CD3 surface expression from a representative experiment. Gray line indicates lenalidomide-treated cells; dark line, vehicle-treated cells. Control IgG1k-PE and forward scatter/side scatter plot are shown. (C) Dose- and time-response curves. The effect of a wider dose range of lenalidomide (0.05-3 μM) on the CD20 and CD52 expression on CLL cells was evaluated at 24, 48, and 72 hours. (D) Lenalidomide induces up-regulation of CD23 and CD38 in CLL cells. CD19⁺ cells were incubated with lenalidomide (0.5 μM) or vehicle control. CD23 and CD38 surface expression was analyzed by flow cytometer after 48 hours of treatment. The graphs show fold change in percentage of CD23⁺ (left) and CD38⁺ (right) cells. n = 6; * P = .001, ** P < .05. (E) Lenalidomide induced modulation of CD20 mRNA transcripts in CLL B cells.