Natural Killer cell receptor ligand (NKRL)

Natural Killer (NK) cell receptor ligands are a diverse group of proteins expressed on the surface of target cells, such as tumor-transformed or virus-infected cells, that serve as recognition signals for NK cells. These ligands include activating molecules like MICA, MICB, and ULBPs (which bind the NKG2D receptor) and CD155 and CD112 (which bind the DNAM-1 receptor), as well as inhibitory molecules like MHC class I proteins. In healthy tissues, activating ligands are typically absent or expressed at low levels, but they are upregulated in response to cellular stress, DNA damage, or malignant transformation, a process known as "induced-self" recognition. Conversely, many tumors downregulate these ligands or shed them from the cell surface to evade immune surveillance. Therapeutic strategies targeting these ligands include the use of monoclonal antibodies to block ligand shedding, the administration of drugs like HDAC inhibitors to upregulate ligand expression, and the development of bispecific or trispecific NK-cell engagers that bridge these ligands to activating receptors on NK cells to enhance anti-tumor cytotoxicity.

Other names

NK receptor ligandsNKG2D ligandsDNAM-1 ligandsStress-induced ligandsNK cell activating ligandsMICA/BULBPsNKG2DL

Upregulation of activating ligand expression on tumor cells to enhance NK cell recognition; blocking of ligand shedding from the cell surface to prevent immune evasion; bridging of ligands to activating receptors on NK cells via multi-specific engagers.