Frequency of Tregs in CML patients at diagnosis, pre-MMR, MMR, MR^4.5, TFR, and in HD. (A) (i) CD4⁺CD25^hiCD127⁻FoxP3⁺ Treg gating. (ii) Treg percentage as a proportion of CD4⁺ T cells. (iii) Representative patient (of 8 patient samples) showing the absolute number of Tregs per microliter (blue) against BCR-ABL1 (red) over time. (B) (i) Effector memory (EM), central memory (CM), naïve (N), terminally differentiated effector memory (TDEM) Treg subset gating. (ii) Percent EM, CM, N, and TDEM subsets in CML patients at diagnosis (n = 18), MMR (n = 25), and MR^4.5 (n = 22) and in HD (n = 5) as a proportion of CD4⁺ T cells. Bars denote the median. ***P ≤ .001; **P ≤ .01; *P ≤ .05.