The 159227 monoclonal antibody specifically recognizes MHC class I polypeptide-related sequence A (MICA) which is also known as MIC-A, MHC class I chain-related protein A, or stress inducible class I homolog. This ~70 kDa single-pass type I transmembrane glycoprotein is encoded by MICA (major histocompatibility complex class I chain-related gene A) which is a highly polymorphic gene. MICA is very homologous to another protein, MICB. Both MICA and MICB are homologous to major histocompatibility complex (MHC) class I molecules although they lack association with β2 microglobulin. MICA and MICB each contain three extracellular Ig domains but have no capacity to bind peptides. MICA is expressed on some gut epithelial cells. Its expression by other epithelial cells and cell types, including fibroblasts and endothelial cells, is induced by stress, eg, stress caused by bacterial and viral infections, autoimmunity, transplantation rejection, or cellular transformation. MICA and MICB are ligands for NKG2D (CD314), an activating receptor expressed by natural killer (NK) cells, γδ T cells, CD8+ αβ T cells, and some CD4+ αβ T cells.
The antibody was conjugated to BD Horizon™ BV650 which is part of the BD Horizon Brilliant™ Violet family of dyes. This dye is a tandem fluorochrome of BD Horizon BV421 with an Ex Max of 405-nm and an acceptor dye with an Em Max at 650-nm. BD Horizon BV650 can be excited by the violet laser and detected in a filter used to detect APC-like dyes (eg, 660/20-nm filter). Due to the excitation and emission characteristics of the acceptor dye, there will be spillover into the APC and Alexa Fluor® 700 detectors. However, the spillover can be corrected through compensation as with any other dye combination.