Killer-cell immunoglobulin-like receptor–Human leukocyte antigen class I ligand system (KIR–HLA class I)

The Killer-cell immunoglobulin-like receptor (KIR)–Human leukocyte antigen (HLA) class I ligand system is a fundamental regulatory mechanism of the innate immune system, primarily controlling the activation and effector functions of Natural Killer (NK) cells and certain T cell subsets (Source: UniProt, P43626; PMID: 29942236). Inhibitory KIRs recognize specific HLA class I molecules on target cells, transmitting signals that prevent NK cell-mediated lysis of healthy self tissues, thereby maintaining self-tolerance (Source: NIH, PMID: 11244035). In oncology, many tumors exploit this system as an immune checkpoint by expressing HLA ligands to suppress NK cell surveillance and escape destruction (Source: PubMed, PMID: 28231464). Therapeutic interventions, notably monoclonal antibodies like lirilumab, are designed to block these inhibitory KIR-HLA interactions to restore and promote anti-tumor immunity (Source: ClinicalTrials.gov, NCT01687712). Beyond cancer, this system is critically involved in the pathogenesis of infectious diseases, autoimmune conditions, and reproductive health, where KIR-HLA genetic diversity influences disease susceptibility and pregnancy outcomes (Source: Wikipedia; PMID: 25308604).

Other names

KIR-HLA axisKiller cell inhibitory receptor systemCD158 familyMHC class I-KIR interactionNK cell checkpoint

Checkpoint inhibition; monoclonal antibodies bind to inhibitory KIR receptors (such as KIR2DL1, KIR2DL2, and KIR2DL3), preventing their interaction with HLA class I ligands (specifically HLA-C) on target cells, which removes the inhibitory signal and enhances Natural Killer (NK) cell-mediated lysis of tumor or infected cells (Source: PubMed, PMID: 28231464).