PDCD1 and infection: These results indicated that the higher level of these cells plays dual functions, especially in the susceptible period of aGVHD and infection.9 The mean of PD-1+CD8+ TSCM-like regulatory cell counts was also calculated, with results similar to the change in proportion (PB: 4986, 2023, 247.3/mL respectively 0–2, 2–4, 4–8 months after HSCT; BM: 8073, 861.7, 136.7, 225.7/mL respectively 0–100, 101–200, 201–400, > 400 days after HSCT).