Increased natural Tregs after AHSCT correlate with thymic function and are associated with clinical response. (A) Percentage of CD4⁺CD25^highFoxP3⁺ Tregs within CD3⁺CD4⁺ T cells and (B) Treg absolute values at baseline (0 months, pretransplant) and following time points in the transplanted patients immunophenotyped by flow cytometry. N = 26 transplanted patients at baseline, n = 15 at 6 and 12 months, and n = 11 at 18, 24, and >24 months. The boundaries of the boxes indicate the 25th and 75th percentiles; lines within the boxes indicate the median, and the whiskers mark the 10th and the 90th percentiles. Plots show mean ± SE. *P < .05; **P < .01 comparing posttransplant values to baseline (Wilcoxon’s). (C) Correlation between the absolute values of RTEs and Tregs (Spearman’s). (D) GITR (left) and CTLA-4 (right) median of fluorescence intensity (MFI) expression by CD4⁺CD25^high Tregs at baseline (Pre-Tx) and 12 months posttransplant. *P < .05; **P < .01 comparing posttransplant values to baseline (Wilcoxon’s). (E) Median (± IQR) baseline percentage of (left) CD4⁺CD25^hiFoxP3⁺ Tregs and (right) FoxP3 expression by CD4⁺CD25^hi Tregs in nonresponder patients (red) after AHSCT or in responder patients (blue). *P < .05 comparing groups (Mann-Whitney U test). (F) Median (± IQR) baseline and 12-month Treg counts and GITR/CTLA-4 expressions by CD4⁺CD25^hi Tregs in nonresponder patients after AHSCT or in responder patients. *P < .05 comparing groups (Mann-Whitney U test) and *P < .05 comparing posttransplant values to baseline (Wilcoxon’s).