Natural killer group 2 member D ligand (NKG2DL) [1.1.1, 1.2.1] (NKG2DL [1.2.1])

Natural killer group 2 member D ligands (NKG2DLs) are a diverse family of MHC class I-like proteins, including MICA, MICB, and the ULBP family (ULBP1-6), that function as critical danger signals for the immune system [1.1.1, 1.2.1]. While generally absent or expressed at low levels in healthy tissues, these ligands are significantly upregulated on the surface of cells undergoing stress, viral infection, or malignant transformation [1.2.2, 1.3.2]. They are recognized by the NKG2D activating receptor found on natural killer (NK) cells, CD8+ T cells, and γδ T cells, where their binding triggers potent cytotoxic activity and cytokine release to eliminate the compromised cells [1.3.1, 1.4.4]. In many cancers, tumor cells evade this surveillance by proteolytically shedding surface ligands into soluble forms (e.g., sMICA/B), which act as decoys to downregulate NKG2D expression on immune effectors [1.4.1, 1.4.2]. Therapeutic approaches targeting this axis include NKG2D-based chimeric antigen receptor (CAR) T cells (e.g., CYAD-01), monoclonal antibodies designed to prevent ligand shedding (e.g., 7C6), and various pharmacological agents like HDAC inhibitors that enhance ligand expression to restore tumor immunogenicity [1.3.1, 1.5.2, 1.5.4]. Understanding the regulation of these ligands is essential for optimizing immunotherapies and overcoming tumor-mediated immune escape mechanisms [1.3.4, 1.3.5].

Other names

MICA [1.1.1]MICB [1.1.1]ULBP1 [1.1.1]ULBP2 [1.1.1]ULBP3 [1.1.1]ULBP4 [1.1.1]ULBP5 [1.1.1]ULBP6 [1.1.1]RAET1E [1.1.1]RAET1G [1.1.1]RAET1H [1.1.1]RAET1I [1.1.1]RAET1L [1.1.1]RAET1N [1.1.1]MHC class I polypeptide-related sequence A [1.3.1]MHC class I polypeptide-related sequence B [1.3.1]Stress-induced ligands [1.3.2]

Activation of NK cells and T cells via NKG2D receptor binding [1.2.1, 1.3.1]; CAR-T cell-mediated lysis of ligand-expressing cells [1.3.1, 1.4.2]; inhibition of proteolytic shedding of MICA/B [1.5.4]; pharmacological induction of ligand expression on tumor cells [1.3.2, 1.5.2].