Donor-derived T_SCM lymphocytes are selectively enriched early after haploidentical HSCT. (A) Flow cytometric plots of CD8⁺ T-cell phenotype from a representative patient (UPN#15) within the LP and at different points after HSCT, as labeled. Top row plots depict the expression of CD45RA and CD62L, which allows the identification of T_CM (CD45RA⁻CD62L⁺), T_EM (CD45RA⁻CD62L⁻), and T_EMRA (CD45RA⁺CD62L⁻). Quadrant frequencies are indicated. To discriminate between T_N and T_SCM, which are both CD45RA⁺CD62L⁺, double-positive cells are gated and CD95 expression is shown in the bottom row plots. T_SCM are identified as CD95⁺, and T_N as CD95⁻. The percentages of T_SCM gated on CD45RA⁺ CD62L⁺ CD8⁺ T lymphocytes are shown. (B) Summary of CD8⁺ T-cell subset distributions, expressed as percentages on total CD8⁺ T cells, at the indicated points post-HSCT. (C) Comparison of CD8⁺ T-cell subset frequencies at day 8 post HSCT. Each dot represents a single patient. (D) Comparison of the absolute numbers of circulating CD8⁺ T cell subsets at day 8 post-HSCT. (E) Comparison of T_SCM frequencies among LP and day 8 post-HSCT. Data are shown as mean values ± SEM of the 20 patients included in the study. (F) Linear regression analysis between CD8⁺ T_SCM counts at day 8 post-HSCT and the serum level of IL-7 measured at day 1 post-HSCT (n = 13). Gray line denotes the best-fit line of the linear regression analysis, whereas black dashed lines indicate the 95% confidence interval. The r² and P value of the slope are reported in the upper-right part of the panel.