The E4.3 monoclonal antibody specifically binds to CD46. CD46 is also known as membrane cofactor protein (MCP). CD46 is a type I membrane glycoprotein composed of two non-disulfide linked α (66 kDa) and β (56 kDa) chains expressed on lymphocytes, monocytes and granulocytes. It is not expressed on erythrocytes or platelets. There are four isoforms of the dimer which function as complement regulatory factors. CD46 promotes the enzymatic degradation of activated C3b and/or C4b deposited on host cells. It also serves as the measles virus receptor.
The antibody was conjugated to BD Horizon™ BUV496 which is part of the BD Horizon Brilliant™ Ultraviolet family of dyes. This dye is a tandem fluorochrome of BD Horizon BUV395 with an Ex Max of 348-nm and an acceptor dye with an Em Max at 496-nm. BD Horizon BUV496 can be excited by the ultraviolet laser (355 nm) and detected with a 515/30 nm filter with a 450LP. Due to the excitation of the acceptor dye by other laser lines, there may be significant spillover into the channel detecting BD Horizon V500 or BV510 (eg, 525/40-nm filter). However, the spillover can be corrected through compensation as with any other dye combination.