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Tuesday 7 June 2016


Definition: Programmed cell death protein-1, also known as PD-1 and CD279, 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. PD-1 binds two ligands, PD-L1 and PD-L2.

PD-1, functioning as an immune checkpoint, plays an important 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).

Targeted therapy

A new class of drugs that block PD-1, the PD-1 inhibitors , activate the immune system to attack tumors and are therefore used with varying success to treat some types of cancer.

See also

- immune checkpoint
- PD-1 inhibitors
- PD-L1