The L17F12 monoclonal antibody specifically binds to CD5 which is also known as Lymphocyte antigen T1 (T1) or LEU1/Leu-1. CD5 is an ~67 kDa single-chain, type 1 transmembrane glycoprotein expressed on most thymocytes, the majority of peripheral T lymphocytes and a subpopulation of B cells. CD5+ B cells produce polyreactive antibodies (mostly IgM). This CD5-specific antibody also reacts with many T-cell leukemias and lymphomas and most Ig+ B-cell chronic lymphoblastic leukemia (B-CLL) cells. CD72 has been shown to be the natural ligand for CD5.
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.