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 BB515 which is part of the BD Horizon Brilliant™ Blue family of dyes. With an Ex Max near 490 nm and an Em Max near 515 nm, BD Horizon BB515 can be excited by the blue laser (488 nm) laser and detected with a 530/30 nm filter. This dye has been exclusively developed by BD Biosciences and is up to seven times brighter than FITC with less spillover into the PE channel. Due to similar excitation and emission properties, BB515, FITC, and Alexa Fluor® 488 cannot be used simultaneously. It is not recommended to use BB515 in cocktails that include Streptavidin conjugates as it may cause high background.