The AER-37 (CRA-1) monoclonal antibody specifically recognizes FcεRIα which is also known as the high affinity immunoglobulin epsilon receptor subunit alpha (Fc-epsilon RI-alpha). FcεRIα is a type I transmembrane glycoprotein that is encoded by FCER1A (Fc fragment of IgE receptor Ia) which belongs to the Ig gene superfamily. FcεRIα serves as the binding subunit for the Fc region of IgE. It forms part of a heterotetrameric, high-affinity IgE Fc receptor (FceR1/FcεR1) that includes signal transducing subunits, one β-chain (FcεRIβ encoded by MS4A2) and two disulfide-linked γ-subunits (FcεRIγ encoded by FCER1G). FcεRIα is normally expressed on basophils and mast cells and can also be expressed on some monocytes, Langerhans cells, dendritic cells, and eosinophils from allergic donors. FcεRIα plays a major role in allergic responses and in the presentation of allergens to the immune system. The AER-37 antibody reportedly does not compete with IgE for FceR1 binding.
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.