CD4⁺ T_SCM preferentially retain CD31 expression by day 8 post-HSCT. (A) Box plots depict the differential expression of CD31 on CD4⁺ T-cell subsets (T_N, T_SCM, T_CM, and T_EM) from healthy subjects (n = 25). (B) Flow cytometry plots of CD31 expression on CD4⁺ T_N, T_SCM, T_CM, and T_EM from a representative patient (UPN#4) at different points after HSCT, as labeled. (C) Kinetics of representation of T_N and T_SCM, expressed as percentage on the total circulating CD4⁺ cells at the indicated points post-HSCT. T_CM and T_EM kinetics are also depicted (gray dashed lines). (D) Box plots show CD31 expression on CD4⁺ T_N, T_SCM, T_CM, and T_EM at the labeled points. Data are shown as average values from the 20 patients included in the study. n.e.: not evaluable.