Interferons (IFNs) are a group of signaling proteins made and released by host cells in response to the presence of several viruses
In a typical scenario, a virus-infected cell will release interferons causing nearby cells to heighten their anti-viral defenses
The mammalian types are designated IFN-α (alpha), IFN-β (beta), IFN-κ (kappa), IFN-δ (delta), IFN-ε (epsilon), IFN-τ (tau), IFN-ω (omega), and IFN-ζ (zeta, also known as limitin)
The IFN-α proteins are produced mainly by plasmacytoid dendritic cells (pDCs)
They are mainly involved in innate immunity against viral infection
The genes responsible for their synthesis come in 13 subtypes that are called IFNA1, IFNA2, IFNA4, IFNA5, IFNA6, IFNA7, IFNA8, IFNA10, IFNA13, IFNA14, IFNA16, IFNA17, IFNA21
These genes are found together in a cluster on chromosome 9
IFN-α is also made synthetically as medication in hairy cell leukemia
The pegylated types are pegylated interferon alfa-2a and pegylated interferon alfa-2b
Alpha interferons are used in the treatment of chronic viral hepatitis (C and B), some solid tumors (e.g., Kaposi sarcomas in patients with HIV infection), melanoma, and certain leukemias