[NK cell receptors and related ligands]

NK cell has antigen-non-specific receptors on its surface. Based on the molecular structure, NK cell receptors can be divided into two types, including Ig superfamily and C-type lectin superfamily. Based on function, NK cell receptors can be divided into activation receptors (NKAR) and inhibition receptors (NKIR). NKAR includes CD16 mediating antibody dependent cytotoxicity, NKR-P1 mediating natural cytotoxicity, KAR conjugated with DAP12 and co-stimulatory receptor. They transduce signal through the ITAM motif in their cytoplasmic region. NKIR mainly include KIR and CD94/NKG2. Their ligands are MHC-I molecules. They are closely related to the recognition of auto cells by NK cells. Inhibition of NKAR activation and cytotoxic effect of NK cells by NKIR are carried out through the ITIM motif and require co-aggregation of NKAR and NKIR.