The UIC2 monoclonal antibody specifically binds to an extracellular epitope of CD243, which is also known as ATP-binding cassette subfamily B member 1 (ABCB1), Multidrug resistance protein 1 (MDR1), or P-glycoprotein 1. CD243 is a transmembrane glycoprotein that spans the membrane 12 times. CD243 acts as an ATP-dependent efflux pump for a large variety of lipophilic molecules and drugs. This efflux activity has been suggested to lead to resistance to the drugs used in chemotherapy. CD243 is expressed by epithelial and endothelial cells, and at low levels by T cells, B cells, NK cells, and hematopoietic stem cells. It may be expressed at high levels by multidrug resistant (MDR) tumor cells. The UIC2 antibody reportedly inhibited the efflux of CD243 substrates from MDR cells and increased the cytotoxicity of certain CD243-transported drugs. The UIC2 antibody reportedly does not crossreact with mouse CD243.
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.