Programmed cell death protein 1

Programmed cell death protein 1 (also known as PD-1 and CD279 (cluster of differentiation 279)) is a protein that in humans is encoded by the PDCD1 gene. PD-1 is a cell surface receptor that belongs to the immunoglobulin superfamily and is expressed on T cells and pro-B cells. It functions as an immune checkpoint and plays a major role in down regulating the immune system by preventing the activation of T-cells, which in turn reduces autoimmunity and promotes self-tolerance. The inhibitory effect of PD-1 is accomplished through 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 (suppressor T cells).

Function

PD-1 is an immune checkpoint receptor that is expressed on the surface of activated T cells, B cells, and myeloid cells. The primary function of PD-1 is to limit the activity of T cells in peripheral tissues during an inflammatory response to infection and to limit autoimmunity.

Clinical significance

PD-1 and its ligands, PD-L1 and PD-L2, are often upregulated in cancer cells and the surrounding microenvironment. This upregulation often leads to the inhibition of T cells that would otherwise recognize and destroy cancer cells. Inhibition of PD-1 or its ligands can restore the cytotoxic activity of T cells against cancer cells, providing the basis for the development of PD-1 inhibitors as cancer therapeutics.

PD-1 inhibitors

PD-1 inhibitors are a type of immunotherapy that block the interaction between PD-1 and its ligands, thereby enhancing the immune system's anti-tumor response. These drugs have shown significant clinical benefits in the treatment of a variety of cancers, including melanoma, non-small cell lung cancer, kidney cancer, bladder cancer, and head and neck cancers.

See also

• Programmed cell death
• Immune checkpoint
• Immunotherapy
• Cancer

References

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• File:Negative, low and high PD-L1 expression by immunohistochemistry.png