The 4G8 monoclonal antibody specifically binds to CD135 which is also known as FMS-like tyrosine kinase 3 (FLT3), Fetal liver kinase 2 (FLK2) and Stem cell tyrosine kinase 1 (STK1). CD135 is a 155-160 kDa type I transmembrane glycoprotein. It belongs to subclass III of the receptor tyrosine kinase (RTK) family which includes receptors for M-CSF (CD115), SCF/c-Kit Ligand (CD117), and PDGF (CD140a and CD140b). CD135 is expressed on multipotential, myelomonocytic and primitive B-cell progenitors. The most primitive hematopoietic progenitor cells express low levels of CD135. CD135 plays the role of growth factor receptor for early hematopoietic progenitors. Reports from studies with knockout mice have shown that targeted CD135 disruption impaired the development of primitive progenitor cells of all hematopoietic lineages with significant impact on lymphopoietic precursors.
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).