The BC4 antibody reacts with the high-affinity IgE Fc receptor (FcεRI) expressed in rat mast cells, basophils, and non-B non-T cells. The rat FcεRI is expressed as a tetrameric molecule consisting of one α chain, one β chain, and two identical γ chains. The BC4 antibody has been reported to detect all three chains of the FcεRI by immunoprecipitation. In the rat model, the β chain (FcRβ) is required for cell-surface expression of the complete FcεRI. This differs from the human FcεRI, which can be expressed in trimer (αγ2) or tetramer forms (βγ2). Furthermore, the FcRβ has been characterized as a potent signaling molecule capable of substantially amplifying Fc-mediated cellular responses. The FcεRI functions to mediate cellular degranulation and the release of histamine, leukotrienes, and various cytokines and chemokines. The structure, expression, function, and signaling mechanisms of the FcεRI have been reviewed.
The antibody was conjugated to BD Horizon BUV615 which is part of the BD Horizon Brilliant™ Ultraviolet family of dyes. This dye is a tandem fluorochrome with an Ex Max near 350 nm and an Em Max near 615 nm. BD Horizon Brilliant BUV615 can be excited by the ultraviolet laser (355 nm) and detected with a 610/20 filter and a 595 nm LP. Due to the excitation of the acceptor dye by the blue/yellow-green laser line, there may be significant spillover into channels detecting PE-CF594 like emissions (eg, 610/20-nm filter).