The B64 monoclonal antibody specifically recognizes Basal Cell Adhesion Molecule (BCAM, B-CAM) which is also known as CD239, Lutheran blood group antigen (Lu), or Lutheran glycoprotein. BCAM (CD239) is a type I transmembrane glycoprotein that is encoded by BCAM [basal cell adhesion molecule (Lutheran blood group)] which belongs to the Ig gene superfamily. Full-length BCAM (CD239) is comprised of an extracellular region with two N-terminal V-type Ig-like domains followed by three C2-type Ig-like domains, a transmembrane region, and cytoplasmic domain of 59 amino acid residues. The extracellular region of this adhesion molecule functions as a receptor for α5-chain containing laminins which are found in basement membranes whereas its cytoplasmic tail may have signal-transduction functions. BCAM (CD239) is expressed on erythrocytes and on the basal layer of vascular endothelial cells or some epithelial cells. BCAM (CD239) is highly expressed on sickle red cells and may play a role in vaso-occlusive crises in sickle cell disease. It is also upregulated upon malignant transformation of some cell types including those found in ovarian carcinomas.
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.