Frequencies of T- and NK-cell subsets during the first cycle of lenalidomide maintenance. Indicated PBMC samples in the x-axes (c indicates cycle; and d, day) were stained with fluorescent-conjugated antibodies to determine the frequencies of CD3⁺ T cells (A), HLA-DR⁺ T-cell subsets (B), CD3⁻CD56/CD16⁺ NK cells (C), and the CD56^dim NK cells (D) by fluorescence-activated cell sorter. Solid lines in the scatter plots indicate the mean values; and dotted lines in the graphs, the mean value found in healthy persons (n = 7).