Programmed death-1（PD-1）/programmed death-ligand 1（PD-L1）, as the important member of B7- CD28 family, is a newly identified negative co-stimulatory pathway. It may play a critical immunoregulatory role, through inhibiting T cells activation and proliferation as well as cytokines production, in chronic diseases such as autoimmune diseases, chronic infections and tumors. Besides discussing the biological characteristics and functions of PD-1/PD-L1, this review mainly explores its regulation on oral chronic diseases including oral lichen planus, chronic periodontitis as well as oral malignant tumors and the therapeutic potential of PD-1/PD-L1 modulation in this filed.
