PDCD1 and neoplasm: Studies have shown that the combination of PD-L1 highly expressed on AML cells and PD-1 on the surface of T lymphocytes can induce them to differentiate and expand into Tregs that highly express Foxp3 and PD-1, and these Tregs release suppressive cytokines, including IL-10 and IL-35, enabling tumor cell immune escape [41].