The 809220 monoclonal antibody specifically recognizes CD56 which is also known as Neural cell adhesion molecule 1 (NCAM-1), Neural cell adhesion molecule (NCAM), or embryonic NCAM (E-NCAM). CD56 (NCAM-1) is a 120-180 kDa type I transmembrane glycoprotein that is encoded by Ncam1 which belongs to the immunoglobulin superfamily (IgSF). Three different isoforms of CD56 (NCAM-1) have been described that vary in their cytoplasmic domains. The 180 kDa long isoform contains five consecutive IgC-like domains followed by two fibronectin type III domains in its extracellular region, a transmembrane sequence and a large cytoplasmic domain. A 140 kDa isoform has a shorter cytoplasmic tail whereas the 120 kDa isoform is glycophosphatidylinositol (GPI)-linked to the cell membrane. CD56 (NCAM-1) functions on cells as a hemophilic or heterophilic adhesion molecule and as a receptor for various ligands including certain growth factors. Throughout development and adulthood, CD56 (NCAM-1) is expressed on various cell types such as neurons where it might play roles in cellular migration, axonal guidance, and synapse formation. It can also be expressed on astrocytes as well as bone marrow neutrophils and some monocytes and might be involved in cellular migration and other functions. Polysialylation of CD56 (NCAM-1) reduces its ability to dimerize and can thereby affect the functions of cells that express it.
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.