Patients with aGVHD had: a) before SCT, higher percentages of CD4+TCM (49 vs 41; p = 0.02) and unswitched memory B cells (4 vs 2; p = 0.04) and lower values of KRECs (p = 0.04); b) at GVHD onset, higher values of RTE, naïve CD4+, CD4+TCM, CD4+TEMRA cells, and all Treg subtypes (p<0.05), and an increased percentage of CD4+ (49 vs 28; p = 0.006) and CD8+TCM cells (7 vs 4; p = 0.04). Here, CD8A is linked to graft versus host disease.