IFNA2: The prototypic human alpha interferon

•IFNA2 was one of the first type I interferon gene cloned in the 1980's.•IFNα2 is one of the most potent interferon α.•IFNα2 is the interferon α subtype used in the clinic.•Its gene structure, expression, signaling and biological functions are reviewed

The human interferon α2 (IFNα2) was the first highly active IFN subtype to be cloned in the early eighties. It was also the first IFN and the first cytokine to be produced and commercialized by the pharmaceutical industry. Ipso facto it became the favorite IFNα subtype for academic researchers. For this fortunate reason IFNα2 has been at the origin of most discoveries related to the mechanism of action of type I interferons.