The O323 monoclonal antibody specifically recognizes CD27 which is also known as Tumor necrosis factor receptor superfamily member 7 (TNFRSF7), T14, Tp55, or S152. CD27 exists as a ~110-120 kDa disulfide-linked homodimer comprised of two single-pass type I transmembrane glycoproteins that are encoded by CD27 (CD27 molecule). CD27 is expressed on medullary thymocytes and T cells, with higher expression on activated T cells, and subsets of mature B cells and natural killer (NK) cells. A soluble 28-32 kDa form of CD27 is produced by lymphocytes upon cellular activation. Binding of the CD27 antigen, expressed on T cells, to its ligand, CD70 (CD27L), provides a costimulatory signal, leading to T cell proliferation, production of cytotoxic T cells, and enhanced production of cytokines. Binding of CD70 to CD27 expressed on B cells leads to B cell proliferation and the generation of plasma cells and immunoglobulin production. The CD27 antigen becomes hyperphosphorylated on serine residues upon activation of T cells. Signaling through the CD27 antigen activates NFκB and stress activated protein kinase (SAPK)/c Jun N terminal kinase (JNK).
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.