The LY9.7.144 monoclonal antibody specifically recognizes CD229 which is also known as SLAM family member 3 (SLAMF3), Lymphocyte antigen 9 (Ly-9), Lgp100, and T100. CD229 is a ~90-120 kDa type I transmembrane glycoprotein that is encoded by Ly9 (lymphocyte antigen 9) which belongs to the Signaling Lymphocytic Activation Molecule (SLAM) family within the immunoglobulin gene superfamily. The extracellular domain of CD229 contains four extracellular Ig-like domains (2 V-set and 2 C-set) extending in order from the N-terminus as V-C2-V-C2. The intracellular region of CD229 contains two ITSMs (immunoreceptor tyrosine-based switch motifs) and serves as a docking site for SH2-binding phosphatases and adapter molecules including SAP and EAT-2. CD229 is variably expressed on most thymocytes, T cells, NKT cells, B cells, NK cells, hematopoietic stem cells and progenitor cells, and monocytes. CD229 participates in homophilic adhesion interactions between these cells and in the regulation of their activation.
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.