The 20/70 monoclonal antibody specifically binds to CD88, which is also known as, Complement component 5a receptor 1 (C5ar1), C5a anaphylatoxin chemotactic receptor, or C5a receptor (C5aR). CD88 belongs to the rhodopsin family of seven-transmembrane G protein-coupled receptors and mediates its effects by binding to the complement activation product, C5a. CD88 is expressed on leucocytes including, neutrophils, monocytes, macrophages, and eosinophils. CD88 may also be expressed on alveolar epithelial cells, endothelial cells, neural stem cells, oligodendrocytes, and on parenchymal cells of lung, liver, kidney and heart. Binding of the proinflammatory C5a anaphylatoxin to CD88 results in G-protein coupling and intracellular signal transduction that mediates intracellular calcium release, chemotaxis, degranulation, cytokine production, and superoxide anion production. The 20/70 antibody can block binding of C5a to CD88 and thus inhibit its biological functions.
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.