Biomarker assays at baseline and 6 months of pomalidomide treatment. (A) CD4, Treg CD4, CD8, natural killer (NK), and B lymphocyte subsets during the time course of pomalidomide treatment. Medians are marked in red. Circled numerals indicate numbers of subjects with ≤1 B cells/µL. (B) Flow cytometry of blood CD3⁺CD4⁺ Treg cells, identifying gating of FoxP3⁺CD25⁺ cells. (C) Changes in the percentage of CD25⁺⁺CD127^dim Treg within CD4⁺ T cells (Wilcoxon paired comparison of 21 subjects evaluated at both time points). (D) IL-2 levels in healthy persons, non-cGVHD patients, and pomalidomide-treated subjects at baseline and 6 months. Mann-Whitney nonparametric comparison of baseline and 6 months shown. (E) IL-2 levels in individual pomalidomide-treated subjects. Wilcoxon paired comparison of 20 subjects evaluated at both time points. (F) Flow cytometry of CD19⁺ B cells at baseline and 6 months identifying gating of CD19⁺⁺CD21^– and of CD11c⁺CD21^– cells. (G) Changes in the percentages of CD19⁺⁺CD21^– B cells. Wilcoxon paired comparison of 12 subjects evaluated at both time points. B, baseline; m, months.