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™ 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.