Natural killer group 2 member D ligands (NKG2DLs) (NKG2DL)

Natural killer group 2 member D ligands (NKG2DLs) are a group of cell surface proteins, including MHC class I polypeptide-related sequence A (MICA), MICB, and the UL16-binding protein (ULBP) family, that serve as critical markers of cellular stress. These ligands are typically absent or expressed at low levels on healthy cells but are significantly upregulated in response to viral infection, DNA damage, or malignant transformation [1] (PMID: 14502289). NKG2DLs are recognized by the activating receptor NKG2D, which is expressed on Natural Killer (NK) cells, CD8+ T cells, and γδ T cells, leading to the targeted destruction of the ligand-expressing cells [2] (PMID: 9497295). In the context of oncology, the broad expression of these ligands across diverse tumor types makes them a compelling target for immunotherapies, such as CAR-T cells (e.g., CYAD-01) and bispecific antibodies [3] (PMID: 30305461). However, a major challenge in targeting NKG2DLs is the tumor-mediated shedding of these proteins from the cell surface, which creates soluble decoys that inhibit immune cell function and facilitate immune evasion [4] (PMID: 18836474). Current research aims to stabilize these ligands on the cell surface or use them as anchors for multi-specific immune engagers to enhance anti-tumor efficacy.

Other names

MHC class I polypeptide-related sequence A (MICA)MHC class I polypeptide-related sequence B (MICB)UL16-binding proteins (ULBP1-6)Stress-induced ligandsNK-activating ligandsAbnormal/stressed patient cells expressing NK-activating ligands

Binding to the NKG2D activating receptor on effector lymphocytes (NK cells, CD8+ T cells) to trigger cell-mediated lysis of the ligand-expressing target cell.