Interferon alpha 1/13 (IFNA1, IFNA13) is synthesized by macrophages and possesses antiviral activities. It is an acid-stable molecule that signals through IFNα/βR, which is also utilized by IFNβ. Interferon stimulates the production of two enzymes: a protein kinase and an oligoadenylate synthetase. IFNA1 is the most abundantly expressed IFNA subtype and primarily originates from plasmacytoid dendritic cells (pDC), which are the earliest cells recruited to the sites of virus entry. Individual IFNA subtypes have been found to exhibit distinct efficacies in terms of viral protection, with IFNA1 demonstrating low potency, as determined by both antiviral and antiproliferative activities. The role of IFN-alpha in the development of autoimmune diabetes can either be suppressive or promotive, suggesting a complex involvement in the etiology of type 1 diabetes.