The L133.1 monoclonal antibody specifically recognizes CD31, the platelet/endothelial cell adhesion molecule-1 (PECAM-1), a 130 to 140-kilodalton (kDa) single-chain integral membrane glycoprotein that is a member of the immunoglobulin gene superfamily. The CD31 antigen is composed of six extracellular immunoglobulin-like domains belonging to the C2 group. C2 domains are also found in other members of the immunoglobulin superfamily, the cell adhesion molecules (CAMs). The CD31 antigen functions as a vascular cell adhesion molecule and is involved in the process of leucocyte migration through the intercellular junctions of vascular endothelial cells. It may also be involved in thrombosis, angiogenesis, wound healing, and inflammation. The CD31 antigen is expressed on endothelial cells, platelets, T-lymphocyte subsets, monocytes, and granulocytes. The CD31 antigen has also been found in metastatic colon carcinoma. The CD31 antigen is the only known member of the CAM family to be expressed on platelets. The antigen is localized at regions of cell-cell contacts and may function as an adhesion molecule, mediating adhesion between leucocytes/endothelial cells, leucocytes/platelets, and endothelial cells/endothelial 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.