NKG2A/CD159a

NKG2A (CD159a), encoded by KLRC1, is an inhibitory C-type lectin receptor that forms obligate heterodimers with CD94 on NK cells and CD8 T cells. The CD94/NKG2A complex recognizes the non-classical MHC class I molecule HLA-E presenting signal peptides derived from classical HLA leaders, and the cytoplasmic ITIM of NKG2A delivers inhibitory signals via SHP phosphatases, protecting healthy HLA-E-expressing cells from NK attack. Elevated NKG2A expression on tumor-infiltrating NK and CD8 T cells is associated with impaired antitumor immunity, and the blocking antibody monalizumab is in clinical development, including combinations with EGFR-directed therapy in head and neck cancer.