Natural killer cell lectin-like receptor subfamily K member 1 (NKG2D)

NKG2D (encoded by the KLRK1 gene) is a potent activating receptor expressed on natural killer (NK) cells, CD8+ T cells, and γδ T cells that serves as a critical mediator of immune surveillance. It recognizes a diverse set of stress-induced ligands, including MHC class I polypeptide-related sequence A and B (MICA/B) and UL16-binding proteins (ULBP1-6), which are typically absent on healthy cells but upregulated in response to DNA damage, malignant transformation, or viral infection. In cancer, the NKG2D-ligand axis is frequently targeted to enhance anti-tumor immunity through CAR-T/NK cells or antibodies that prevent the proteolytic shedding of ligands, a common immune escape mechanism. Conversely, in autoimmune and inflammatory diseases such as Crohn's disease and rheumatoid arthritis, the pathway is often over-activated, contributing to chronic tissue damage and making NKG2D antagonism a viable therapeutic strategy. The high degree of ligand polymorphism and the immunosuppressive effects of soluble ligands remain significant challenges in the clinical development of therapies targeting this axis.

Other names

KLRK1CD314NKG2-DKiller cell lectin-like receptor K1NKG2D-ligand axisMICA/B-NKG2D pathway

NKG2D receptor antagonism; NKG2D receptor activation; Inhibition of MICA/B shedding; CAR-T/NK cell targeting of NKG2D ligands; IL-15 mediated upregulation of NKG2D