CD4⁺and CD8⁺T-cell PD-1 expression in CML patients at diagnosis, pre-MMR, MMR, MR^4.5, TFR, and in HD. (A) CD3⁺/CD4⁺/CD8⁺ T-cell gating to assess PD-1 expression. CD4⁺ and CD8⁺ T-cell PD-1⁺ expression is shown as a percentage of total lymphocytes. (B) Representative patient (of 8 patient samples) showing the absolute number of CD4⁺PD-1⁺ (blue) and CD8⁺PD-1⁺ (green) T cells per microliter against BCR-ABL1 (red) over time. Bars denote the median. ***P ≤ .001; **P ≤ .01; *P ≤ .05.