The 837535 monoclonal antibody specifically recognizes Sialic acid-binding Ig-like lectin 8 (Siglec-8) which is also known as Sialoadhesin family member 2 (SAF-2). Siglec-8 is a single-pass, type I transmembrane glycoprotein that is encoded by SIGLEC8 which belongs to the Sialic acid-binding Ig-like lectins (Siglecs) superfamily. Siglec-8 has an Ig-like V-set domain followed by two Ig-like C-type domains in its extracellular region. Its intracellular region contains an immunoreceptor tyrosine-based inhibitory motif (ITIM) and an immunoreceptor tyrosine-based switch motif (ITSM) which might contribute to inhibitory signal transduction upon engagement of this receptor. A short form of Siglec-8 that results from alternative splicing and which lacks most of the intracellular domain has also been identified. Siglec-8 is expressed on eosinophils and mast cells, and weakly on basophils. Siglec-8 appears to serve as an adhesion molecule which mediates cell-cell interactions through its binding to 6' sulfated sialyl Lewis X carbohydrate structures. Siglec-8 seems to be involved in signal transduction since engagement of Siglec-8 can induce apoptosis in eosinophils or inhibit mast cell degranulation.
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.