Natural killer cell lectin-like receptor subfamily C member 1 (NKG2A)

Natural killer cell lectin-like receptor subfamily C member 1 (NKG2A) is an inhibitory immune checkpoint receptor predominantly expressed as a heterodimer with CD94 on natural killer (NK) cells and some CD8+ T cells. NKG2A recognizes the non-classical MHC class I molecule HLA-E (in humans), which presents conserved signal peptides from other HLA-I molecules. Engagement of NKG2A/CD94 by HLA-E transmits inhibitory signals via ITIM motifs in its cytoplasmic tail, reducing NK cell activation and cytotoxicity. This interaction maintains self-tolerance, regulates immune responses in health and disease (notably cancers and infections), and supports homeostasis by preventing excessive proliferation and activation-induced cell death. NKG2A is a validated immunotherapeutic target; monoclonal antibodies blocking NKG2A (such as monalizumab) are under clinical investigation to enhance anti-tumor and anti-viral immunity. The receptor’s function must be contextually balanced to avoid immune pathology, especially following blockade in cancer or transplantation settings.

Other names

CD159aKLR C1CD94/NKG2ANKG2A receptorKLRK1A

Drugs (e.g., monalizumab) block inhibitory signaling by preventing NKG2A from recognizing HLA-E on target cells, thereby enabling increased NK cell (and some CD8 T cell) cytotoxicity against cancer or virally infected cells. Immune checkpoint blockade mechanism, similar in concept to anti-PD-1/PD-L1 agents