- Human pathology

Home > A. Molecular pathology > PD-L1


Friday 20 October 2006

B7-H1; CD274; Programmed cell death protein 1; PDL1


Definition: PD-L1 (also called B7-H1 ), a cell-surface molecule that is widely distributed in tissues.

Programmed death-ligand 1 (PD-L1) is a 40kDa type 1 transmembrane protein that has been speculated to play a major role in suppressing the immune system during particular events such as pregnancy, tissue allografts, autoimmune disease and other disease states such as hepatitis.

Normally the immune system reacts to foreign antigens where there is some accumulation in the lymph nodes or spleen which triggers a proliferation of antigen-specific CD8+ T cell.

The formation of PD-1 receptor / PD-L1 or B7.1 receptor /PD-L1 ligand complex transmits an inhibitory signal which reduces the proliferation of these CD8+ T cells at the lymph nodes and supplementary to that PD-1 is also able to control the accumulation of foreign antigen specific T cells in the lymph nodes through apoptosis which is further mediated by a lower regulation of the gene Bcl-2.


PD-L1, the ligand for PD-1 , is highly expressed in several cancers and hence the role of PD-1 in cancer immune evasion is well established. (PMID 26562159, PMID 26408403, PMID 24647569 , PMID 24217091 and PMID 23676558)

Monoclonal antibodies targeting PD-1 that boost the immune system are being developed for the treatment of cancer. Many tumor cells express PD-L1, an immunosuppressive PD-1 ligand.

Inhibition of the interaction between PD-1 and PD-L1 can enhance T-cell responses in vitro and mediate preclinical antitumor activity. This is known as " immune checkpoint blockade ".

See also : PD-L1 study in pathology

See also

- PD-1
- immune checkpoint

Paywall References

- Oncologists await historic first: a pan-tumor predictive marker, for immunotherapy.

- Yao S, Chen L. Reviving exhausted T lymphocytes during chronic virus infection by B7-H1 blockade. Trends Mol Med. 2006 Jun;12(6):244-6. PMID: 16650803