The GIR-208 antibody recognizes the extracellular region of CD119 which is also known as the alpha chain subunit (80-95 kDa glycoprotein) of the human interferon-γ receptor (IFN-γRα). The functionally active-form of the human IFN-γ receptor consists of two (or more) subunits, with IFN-γRα responsible for IFN-γ binding and both the IFN-γRα and β chains required for the transduction of biologic responses. The IFN-γ receptor α chain (CD119) is expressed on the surface of most human cells (except mature erythrocytes) including monocytes, macrophages, T cells, B cells, NK cells, neutrophils, fibroblasts, epithelial cells, and endothelium. Binding of 125I-labeled GIR-208 antibody to IFN-γRα+ cells is reported to be specifically inhibited in the presence of excess IFN-γ. GIR-208 does not cross react with IFN-γ as tested by ELISA. The ability of this antibody to bind to IFN-γ receptors of species other than human has not been determined. The immunogen used to generate this hybridoma was human IFN-γRα purified from human placenta. The GIR- 208 has been reported to block the binding of 125I-human IFN-γ to IFN-γRα+ cells as well as purified, soluble human IFN-γRα. GIR-208 is a neutralizing antibody that has been shown to neutralize the anti-viral activity of IFN-γ on WISH cells in a dose-dependent fashion.
The antibody was conjugated to BD Horizon™ BUV496 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 496-nm. BD Horizon BUV496 can be excited by the ultraviolet laser (355 nm) and detected with a 515/30 nm filter with a 450LP. Due to the excitation of the acceptor dye by other laser lines, there may be significant spillover into the channel detecting BD Horizon V500 or BV510 (eg, 525/40-nm filter). However, the spillover can be corrected through compensation as with any other dye combination.