The U29-93 monoclonal antibody specifically binds to the mouse Interleukin-33 Receptor (IL-33 Receptor, or IL-33R) which is also known as ST2. The IL-33R exists in either a type I transmembrane or soluble glycoprotein form. These IL-33R forms are encoded by the Il1rl1 (Interleukin-1 receptor-like 1) gene which belongs to the IL-1 Receptor family within the Ig superfamily. The IL-33R is expressed by subsets of T cells, including Th2-like cells and some regulatory T cells, as well as some innate lymphocytes, eosinophils, basophils, and mast cells. The IL-33R (also known as the IL-33R alpha subunit, or IL-33Rα) binds IL-33 and complexes with the IL-1R Accessory Protein (IL1RAP) to form a functional signaling receptor complex that can induce the production of T helper type 2 (Th2) cytokines. The soluble IL-33R may function as a decoy receptor which can block the binding of IL-33 to the transmembrane IL-33R. The IL-33R plays roles in inflammation, immunity, and allergy.
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.