MHC class I chain-related protein B (MICB) (MICB)

MICB (MHC class I chain-related protein B) is a stress-induced ligand for the NKG2D activating receptor expressed on the surface of immune cells including natural killer cells, cytotoxic T lymphocytes, and gamma-delta T cells[1]. As a transmembrane protein with three conserved structural domains, MICB is normally absent or expressed at low levels on healthy cells but is induced on tumor cells, virus-infected cells, and cells under stress, serving as an important "danger signal" for immune surveillance[1][2]. MICB binding to NKG2D triggers an intracellular signaling cascade through the adaptor protein DAP10 that activates innate and adaptive immune responses, leading to cytokine secretion and cytotoxic granule release[1]. However, exposure to MICB-expressing target cells can paradoxically reduce NK cell cytotoxic capacity through receptor internalization and transfer of NKG2D and MICB between cells at the immunological synapse, potentially allowing tumors to evade immune detection[2]. Genetic polymorphisms in MICB, such as the D136N variant, affect the binding affinity for NKG2D and consequently alter the magnitude of immune activation, with implications for disease susceptibility including acute lung injury[4]. Understanding MICB biology and its interaction with NKG2D presents opportunities for enhancing anti-tumor immunity or modulating excessive immune responses in inflammatory conditions.

Other names

MIC class I chain-related protein Bstress-induced ligand for NKG2D

Therapeutic strategies targeting the NKG2D/MICB axis could enhance NK cell activation for cancer immunotherapy or modulate immune responses in inflammatory conditions. The MICB D136N variant results in reduced NKG2D signaling and reduced NK cell function, suggesting that modulating MICB expression or its interaction with NKG2D could be therapeutically relevant.