T_reg reconstitution after SCT. Using flow-based frequency enumeration and absolute lymphocyte counts acquired from a complete blood count obtained on the same day, relative and absolute numbers of CD4⁺CD3⁺, CD4⁺FOXP3^–, and CD4⁺FOXP3⁺ were calculated for healthy donors (n = 21) (○), patients with leukemia at baseline, prior to allogeneic transplantation (n = 21) (pre; □), and patients after SCT (n = 21) at regular intervals: days +30 (▾), +45 (♦), +60 (•), +90 (▪), and +120 (▴). Bars indicate median values. Samples obtained following DLI are presented as symbols in red. Compared to healthy donors, on day 30 after SCT, circulating CD4⁺ and CD4⁺FOXP3^– T-cell compartments were significantly reduced (A-B, D-E), whereas the percent of CD4⁺ subset composed of FOXP3⁺ cells was significantly increased (C). Bars represent median values.