The WM59 monoclonal antibody specifically binds to platelet endothelial cell adhesion molecule-1, (PECAM-1, PECAM1), which is also known as GPIIA', or EndoCAM. CD31 is a 130 kDa type I transmembrane glycoprotein that belongs to the Ig gene superfamily. CD31 has wide tissue distribution and is expressed on platelets, monocytes, granulocytes, NK cells, T cell subsets, and in high amounts on endothelial cells. CD31 functions as a vascular endothelial cell adhesion molecule and is involved in the transendothelial migration of leucocytes in inflammatory responses. It might be involved in thrombosis, angiogenesis, and wound healing. The WM59 appears to recognize an epitope proximal to extracellular domain 2 of CD31.
Clone WM59 also cross-reacts with peripheral blood platelets and leukocytes of baboon, and both rhesus and cynomolgus macaque monkeys. The staining intensity of WM59+ platelets is similiar to that observed with peripheral blood platelets from normal human donors. Lymphocytes, monocytes, and granulocytes react less with WM59 than normal human leukocytes.
The antibody was conjugated to BD Horizon™ BUV563 which is part of the BD Horizon Brilliant™ Ultraviolet family of dyes. This dye is a tandem fluorochrome of BD Horizon BUV395 which has an Ex Max of 348 nm and an acceptor dye. The tandem has an Em Max at 563 nm. BD Horizon BUV563 can be excited by the 355 nm ultraviolet laser. On instruments with a 561 nm Yellow-Green laser, the recommended bandpass filter is 585/15 nm with a 535 nm long pass to minimize laser light leakage. When BD Horizon BUV563 is used with an instrument that does not have a 561 nm laser, a 560/40 nm filter with a 535 nm long pass may be more optimal. Due to the excitation and emission characteristics of the acceptor dye, there may be spillover into the PE and PE-CF594 detectors. However, the spillover can be corrected through compensation as with any other dye combination.