Interferons, IFNs

Interferons (IFNs) are a group of signaling proteins made and released by host cells in response to the presence of several viruses. IFNs belong to the large class of proteins known as cytokines. Interferons are named for their ability to "interfere" with viral replication by protecting cells from virus infections. Production of interferons occurs mainly in response to microbes, such as viruses and bacteria, and their products. More than twenty distinct IFN genes and proteins have been identified in animals, including humans. They are typically divided among three classes: Type I IFN, Type II IFN, and Type III IFN. All interferons share several common effects: antiviral, up-regulate major histocompatibility complex molecules, and increase immunoproteasome activity. Interferon therapy is used (in combination with chemotherapy and radiation) as a treatment for some cancers.