Impact of the signal path PD-1/PD-L1 on Treg cells and tumor cells

Programmed death-1 (PD-1) and its ligand PD-L1 are the major members of inhibitory costimulatory molecules and express high in a variety of tumor cells and their associated cells surface,while the proportion of regulatory T cells (Tregs) are abnormally elevated in tumor infiltrating T lymphocytes cells.PD-L1 combined with PD-1 and Treg help tumors evade immune clearance,weaken immune responses and induce immune tolerance.New researches find that PD-L1 plays an important role in the development and function maintenance of inducible Treg (iTreg),and PD-L1 signal can change initial CD4 + CD25-T cells into iTreg to play a role of immunosuppression.Research on PD-1 signaling pathway can provide a new theoretical basis for the inhibition of tumor immune escape in clinical application of immunotherapy and better treatments. Key words: Neoplasms;  T-lymphocytes;  Tumor escape;  Programmed cell death 1 receptor