PD-1/PDL-1 Signaling Pathway

1. PD-1/PDL-1 Signaling Pathway Programmed cell death protein 1, also known as PD-1 and CD279, is a cell surface receptor that plays an important role in down-regulating the immune system and promoting self-tolerance by suppressing T cell inflammatory activity. In humans, it is encoded by the PDCD1 gene. PD-1 is a member of the immunoglobulin superfamily and is expressed on T-cells and pro-B cells. As a receptor, PD-1 has two ligands, PD-L1 (B7-H1) and PD-L2 (B7-DC). When PD-1 binds its ligands, it will induce a dual mechanism of promoting apoptosis (programmed cell death) in antigen-specific T-cells in lymph nodes while simultaneously reducing apoptosis in regulatory T-cells (anti-inflammatory, suppressive T-cells). Depending upon the previous study, we find PD-L1 is responsible for tumor immune modulation. Because the binding affinity of PD-1 with PD-L1 is 3 times greater than the affinity between PD-1 for PD-L2 and PD-L1 expressions in tumor cells and hematopoietic cells are determined by the stimulation of pro-inflammatory cytokines such as IFN-γ and TNF-α. While PD-L1 is expressed in a wide range of hematopoietic and non-hematopoietic cells, PD-L2 has restricted expression on macrophages, dendritic cells (DCs) and mast cells in the secretion of IL-4 and IFN – γ . It has been recently reported that PD-L2 interacts with repulsive guidance molecule B (RGMB) of macrophage (M8) proteins. Although, there are several reports on PD-L2, little information is available about its role in cancer immunosuppression. https://www.creative-diagnostics.com/pd-1-pd-l1-signaling-pathway.htm