Mouse Programmed Cell Death Protein 1 (PDCD1) Protein

Background

Programmed cell death 1 (PDCD1), commonly referred to as PD-1, is a transmembrane protein and immune checkpoint receptor expressed primarily on the surface of T cells, B cells, and some myeloid cells. PD-1 is encoded by the PDCD1 gene and plays a pivotal role in regulating immune responses by inhibiting T-cell activation, particularly in peripheral tissues during inflammation. It serves as a checkpoint receptor that, when engaged, dampens the immune response, promoting self-tolerance and preventing autoimmune reactions. PD-1 binds to its ligands, PD-L1 (CD274) and PD-L2 (PDCD1LG2), which are expressed on antigen-presenting cells (APCs) and various tissue cells, particularly in inflamed or tumor environments. The PD-1 pathway is critical for maintaining immune homeostasis, particularly in contexts where a controlled immune response is necessary, such as in infection and inflammation, and in preventing autoimmunity. PD-1 is often upregulated in chronic infections and cancer, where it contributes to immune exhaustion by inhibiting the function of T cells that would otherwise target infected or malignant cells. Given its role, PD-1 and its ligands have become significant targets for immunotherapy, especially in oncology, where blocking the PD-1/PD-L1 interaction can reinvigorate anti-tumor immunity.