Tumor cell surface ligands recognized by cytotoxic immune effector receptors

Tumor cell surface ligands recognized by cytotoxic immune effector receptors are a diverse group of molecules, including MHC class I polypeptide-related sequence A/B (MICA/B), UL16-binding proteins (ULBPs), and Natural killer cell cytotoxicity receptor 3 ligand 1 (B7-H6), that are upregulated on malignant cells in response to cellular stress or transformation (NIH, PubMed). These ligands serve as critical danger signals that are recognized by activating receptors such as Natural killer group 2 member D (NKG2D), Natural killer cell p30-related protein (NKp30), and DNAX accessory molecule-1 (DNAM-1) on natural killer (NK) cells and certain T cell subsets (NIH). Upon binding, these interactions trigger the release of cytotoxic granules and pro-inflammatory cytokines, leading to the direct lysis of the tumor cell (PubMed). In the context of cancer, tumors often evade this immune surveillance by shedding these ligands from their surface or downregulating their expression, which creates soluble decoys that inhibit immune function (NIH). Therapeutic strategies targeting these ligands include monoclonal antibodies, bispecific engagers, and chimeric antigen receptor (CAR) therapies designed to restore or enhance immune recognition and eliminate tumor cells (NIH).

Other names

Activating natural killer cell ligandsStress-induced ligandsNKG2D ligandsNatural cytotoxicity receptor ligandsNCR ligandsMICA/B and ULBPs

Drugs targeting these ligands typically work by either directly binding the surface-expressed molecules to induce antibody-dependent cellular cytotoxicity (ADCC), or by acting as bispecific engagers that bridge the tumor-expressed ligands to activating receptors on NK or T cells. Additionally, some therapies aim to inhibit the proteolytic shedding of these ligands (e.g., via ADAM10/17 inhibition) to maintain high surface density and enhance immune recognition.