IFN-α is a cytokine that has an immunomodulatory function. It plays an important role not only in antiviral activity but also in several physiologic functions, such as activation of dendritic cells and accelerated expression of major histocompatibility complex I and II molecules that may cause increased antigen presentation. In humans, the type I IFN system consists of a family of IFN proteins encoded by at least 13 IFN alpha (IFNA) subtype genes (IFN-α1, -α2, -α4, -α5, -α6, -α7, -α8, -α10, -α13, -α14, -α16, -α17 and -α21), and one IFN beta gene (IFNB), one IFN-Epsilon gene, one IFN-Kappa gene, and IFN-Omega gene, all of which bind to the type I interferon receptor composed of the IFNAR1 and IFNAR2 chains.