Stress-inducible NKG2D ligand

Stress-inducible NKG2D ligands are a group of cell-surface molecules that are minimally expressed on healthy cells but rapidly upregulated in response to cellular stress such as infection, DNA damage, or transformation (as in cancer)[1][2][4]. They include MHC class I chain-related proteins A and B (MICA, MICB) and the UL16-binding protein (ULBP) family (ULBP1–6) in humans[1][10]. These ligands are recognized by the activating immune receptor NKG2D, which is present on natural killer (NK) cells and subsets of T cells, and enable immune recognition and destruction of stressed or transformed cells, playing a vital role in tumor and viral immune surveillance. Their expression and function are regulated by stress-activated pathways including DNA damage response, oxidative stress, and cellular senescence[3][4][5]. In cancer, tumor cells often evolve mechanisms to evade recognition, such as shedding of these ligands as soluble decoys, diminishing their effectiveness and even impairing NK cell function[8][10]. While they are key immunological targets in oncology and infectious disease, their non-specific or aberrant activation can lead to immune-related side effects, posing challenges for therapeutic exploitation[1][2][8][10].

Other names

NKG2D ligandNKG2D stress ligandMICAMICBULBP1ULBP2ULBP3ULBP4ULBP5ULBP6MIC ligandUL16-binding protein

Drug-induced upregulation or stabilization of ligand expression to sensitize tumor cells for immune attack Inhibition of ligand shedding or release to maintain cell-surface recognition