Correlation between CD3⁺CD8⁺ and CD4⁺CD25⁺ T cells in active cGVHD. (A) Percent CD3⁺CD8⁺ in PBLs was measured by flow cytometry in patient and donor samples. Lines represent median values. (B) Percent CD4⁺CD25⁺ and CD3⁺CD8⁺ T cells in total PBLs are shown for patients with cGVHD. Correlation between the 2 variables was calculated using a rank-based Spearman test (r_s = -0.81, P < .001).