The MIH18 monoclonal antibody specifically binds to CD273 which is also known as the Programmed Death Ligand 2 (PD-L2) and B7-DC. CD273 is a type 1 transmembrane glycoprotein member of the B7 family and Ig superfamily. CD273 serves as a ligand for CD279, the Programmed Death 1 (PD-1) receptor. CD273 is expressed by dendritic cells, activated monocytes, medullary thymic epithelial cells, placental trophoblasts, and myocardial endothelium. CD273 can function as a coinhibitor of T cell functions by acting through CD279. Monoclonal antibodies that block the CD273 and CD279 interaction result in enhanced T cell proliferation and cytokine production. Thus, CD273 can play an important role in regulating T cell responses. Clone MIH18 is reportedly a blocking antibody.
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.