The M89D3 monoclonal antibody specifically recognizes CD31, which is also known as platelet endothelial cell adhesion molecule -1 (PECAM-1), a single chain, type I transmembrane protein of approximately 130-140 kDa. CD31 is a member of the immunoglobulin supergene family. Its extracellular region is composed of 574 amino acids and contains six C2-type Ig domains, and the intracellular region is composed of 118 residues. CD31 (PECAM-1) is expressed on endothelial cells, platelets, monocytes, neutrophils and NK cells. It has also been observed on subsets of T cells, but not on circulating B cells. It has been implicated in a number of cellular phenomena, including vascular wound healing, angiogenesis, and transendothelial migration of leukocytes and platelet aggregation in inflammatory responses.
The antibody was conjugated to BD Horizon™ BUV661 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 661-nm. BD Horizon Brilliant BUV661 can be excited by the ultraviolet laser (355 nm) and detected with a 670/25 filter and a 630 nm LP. Due to cross laser excitation of this dye, there may be significant spillover into channels detecting APC-like emissions (eg, 670/25-nm filter).
Due to spectral differences between labeled cells and beads, using BD™ CompBeads can result in incorrect spillover values when used with BD Horizon BUV661 reagents. Therefore, the use of BD CompBeads or BD CompBeads Plus to determine spillover values for these reagents is not recommended. Different BUV661 reagents (eg, CD4 vs. CD45) can have slightly different fluorescence spillover therefore, it may also be necessary to use clone-specific compensation controls when using these reagents.