The E3 monoclonal antibody specifically recognizes CD307a which is also known as Fc receptor-like protein 1 (FCRL1), Fc receptor homolog 1 (FCRH1), or Immune receptor translocation-associated protein 5 (IRTA5). CD307a (FCRL1) is a type I transmembrane glycoprotein that belongs to the IRTA gene family within the Ig gene superfamily. It has three extracellular Ig-like domains, a glutamic acid residue in its transmembrane region, and two consensus immunoreceptor tyrosine-based activation motifs (ITAMs) in its cytoplasmic domain. CD307a (FCRL1) bears sequence homology to classical Fc receptors. CD307a (FCRL1) is first expressed on pre-B cells and increases with maturation being expressed on naïve and memory B cells. It is downregulated by activated germinal center (GC) B cells. It may also be expressed by B cell-derived leukemia and lymphoma cells. CD307a may play key roles in B cell activation, differentiation and effector functions.
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).