Low-dose decitabine had no influence on the apoptosis of PBMCs from patients with ITP or healthy control subjects, but significantly elevated the percentage of Treg cells in patients with ITP without changing the percentage of CD4⁺ T cells in PBMCs. (A) Representative dot plots of flow cytometry analysis of apoptosis in PBMCs from patients with ITP. The percentage of Annexin-positive and propidium iodide (PI)-negative cells in PBMCs showed the cell apoptosis rate. (B,C) Decitabine induced apoptosis of PBMCs from healthy control subjects and patients with ITP at doses of 1 μM and 10 μM (n = 6). (D-F) Percentages of Treg cells in CD4⁺ T cells were significantly increased by decitabine at the doses of 10 nM and 100 nM in patients with ITP (n = 11). (G-I) In cultured isolated CD4⁺ T cells, low-dose decitabine (100 nM) significantly increased the percentage of Treg cells in patients with ITP (I; n = 7), but not in healthy control subjects (H; n = 8). *P < .05, **P < .01. Dec, decitabine; HC, healthy controls; ns, not significant.