Interferon-gamma

Interferon-gamma (IFN-γ) is a dimerized soluble cytokine that is the only member of the type II class of interferons. The existence of this interferon, which early in its history was known as immune interferon, was recognized in 1970 when tuberculin-sensitized peritoneal cells were challenged with PPD and resulting supernatants were shown to inhibit growth of vesicular stomatitis virus. That report also contained the basic observation underlying the now widely employed interferon gamma release assay used to test for TB. This interferon was later called macrophage-activating factor, a term now used to describe a larger family of proteins to which IFN-γ belongs. In humans, the IFN-γ protein is encoded by the IFNG gene.