Immunologic responses to low-dose decitabine in patients with ITP. (A-E) Percentages of Treg, Th1, Th17, Th2, and Th22 cells in peripheral blood were analyzed by using flow cytometry. Treg cells (n = 22), Th1 cells (n = 17), Th17 cells (n = 15), Th2 cells (n = 8), and Th22 cells (n = 16) in CD4⁺ T cells before and after decitabine treatment are shown. (F) Ex vivo suppression assays were performed to examine the suppressive activity of Treg cells obtained from patients with ITP before and after decitabine treatment. CFSE-labeled CD4⁺CD25^– Teff cells were stimulated and cocultured with Treg cells from each patient. Representative histograms show proliferation of CD4⁺ Teff cells with or without Treg cells before (above) or after (below) decitabine treatment. (G-H) Treg cell–mediated suppression of CD4⁺ Teff cell proliferation was measured using division index before and after decitabine treatment (n = 14). (I) Decitabine enhanced immunosuppressive function of Treg cells. *P < .05, **P < .01, ****P < .0001. NR, nonresponders; R, responders.