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 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).