Natural cytotoxicity receptor ligand (NCRL) (NCRL)

Natural cytotoxicity receptor (NCR) ligands are a heterogeneous group of molecules expressed on the surface of tumor cells or virally infected cells that bind to and activate the NCRs—NKp30 (NCR3), NKp44 (NCR2), and NKp46 (NCR1)—on Natural Killer (NK) cells. These interactions are fundamental to the innate immune system's ability to recognize and eliminate transformed or stressed cells without prior antigen exposure (Kruse et al., 2014; Moretta et al., 2001). Key ligands include B7-H6 and BAG6 for NKp30, a specific isoform of MLL5 and cell-surface PCNA for NKp44, and viral hemagglutinins or heparan sulfate proteoglycans for NKp46 (Brandt et al., 2009; Baychelier et al., 2013; Mandelboim et al., 2001). In oncology, the upregulation of these ligands, particularly B7-H6, makes them attractive targets for chimeric antigen receptor (CAR) T-cell therapy and multi-specific NK cell engagers (Wu et al., 2015; Gauthier et al., 2019). However, tumors often employ evasion strategies, such as shedding these ligands into a soluble form that acts as a decoy, thereby inhibiting NK cell function and promoting immune escape (Schlecker et al., 2010). Therapeutic strategies currently focus on using multi-specific NK cell engagers (BiKEs and TriKEs) that bind to NCRs like NKp46 to potently activate NK cells against ligand-expressing tumor cells (Gauthier et al., 2019).

Other names

NCR ligandsNKp30 ligandsNKp44 ligandsNKp46 ligandsB7-H6NCR3LG1BAG6BAT3MLL5KMT2EPCNAViral hemagglutinin

Activation of Natural Killer (NK) cells through binding to Natural Cytotoxicity Receptors (NKp30, NKp44, NKp46), triggering degranulation and lysis of target cells.