The ACT35 monoclonal antibody specifically binds to CD134 which is also known as OX40. The 35 kDa CD134 polypeptide is encoded by the TNFRSF4 gene. CD134 is a type I integral membrane glycoprotein and member of the tumor necrosis factor/nerve growth factor receptor (TNFR/NGFR) family. CD134 is expressed on activated T lymphocytes, hematopoietic precursor cells and fibroblasts. CD134 functions as a T cell costimulatory receptor when bound by OX40 Ligand/TNFSF4 that is expressed by antigen presenting cells. CD134 thereby plays roles in T-cell activation as well as the regulation of differentiation, proliferation or apoptosis of normal and malignant lymphoid cells. Analysis of the nucleotide sequence of the human TNFRSF4 cDNA reveals strong homology with the rat Tnfrsf4 cDNA sequence. OX40 was clustered as CD134 in the Sixth International Workshop on Human Leukocyte Differentiation Antigens.
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.