Patients treated with vorinostat have increased Tregs with greater suppressive function and increased acetylation of STAT-3 and IDO expression after allo-HCT. Triangles and black bars denote patients who received vorinostat. Circles and open bars denote control patients. All plots include, or are representative of, data from at least 2 independent experiments. Mean values ± SEM are plotted in B and F. Median values ± interquartile range are plotted in all other panels. (A-B) CD25⁺CD127⁻ cells within the CD4⁺ population of PBMCs 30, 100, and 180 days after allo-HCT. Day 30: control, n = 22; study, n = 36. Day 100: control, n = 11; study, n = 16. Day 180: control, n = 6; study, n = 8. *Control vs study, P = .01; **P = .007; ***P = .06. (C) Foxp3 expression in PBMCs 100 and 180 days after allo-HCT. Data are expressed relative to glyceraldehyde-3-phosphate dehydrogenase copy number. Day 100: control, n = 6; study, n = 6. Day 180: study, n = 9. (D) Methylation of the Foxp3 TSDR in purified CD4⁺CD25⁻ conventional (Tconv, open icons) and CD4⁺CD25⁺ regulatory (Treg, black icons) T cells 100 days after allo-HCT. Control, n = 9; study, n = 11. (E) CD4⁺CD25⁺CD45RA⁺CD31⁺ RTE 100 days after allo-HCT. Control, n = 5; study, n = 6. (F) Suppression of effector Tconv proliferation to anti-CD3 and anti-CD28 stimulation by autologous Tregs 100 days after allo-HCT. Control, n = 8; study, n = 10. *P = .04; **P = .07. (G) Levels of Ac- and phosphorylated (P)-STAT-3 30 and 100 days after allo-HCT. Ac- and P-STAT-3 levels normalized to total STAT-3. Day 30, control, n = 3 to 6; study, n = 5; Day 100: study, n = 6. (H) IDO messenger RNA (mRNA) expression 100 days after allo-HCT. Values are expressed relative to glyceraldehyde-3-phosphate dehydrogenase mRNA copy number. Control, n = 6; study, n = 6.