Interferon
Say it: in-tur-FEER-on
An interferon is a cytokine that cells release when infected by a virus, putting nearby cells into an antiviral state and activating immune cells.
Also: interferons, IFN
Definition
What is an interferon?
Interferons are a family of signaling proteins, a kind of cytokine, named for their ability to interfere with the replication of viruses. Alick Isaacs and Jean Lindenmann described the effect in 1957. Three types are recognized. Type I interferons, chiefly interferon-alpha and interferon-beta, are made by many kinds of cells once they detect viral nucleic acid. Type II has a single member, interferon-gamma, produced mainly by T cells and natural killer cells. Type III, the interferon-lambdas, act mostly on epithelial surfaces such as the airways and gut.
A virus-infected cell usually cannot save itself, but the type I interferon it releases binds receptors on neighboring cells and switches on hundreds of interferon-stimulated genes. Their products slow protein synthesis, break down RNA and block viral assembly, so the virus spreads more slowly. Interferons also increase MHC class I display, which helps cytotoxic T cells spot infected cells, and they stimulate NK cells, while interferon-gamma is the main activator of macrophages. The fever, aches and tiredness of flu-like illness are partly caused by interferons.
Laboratory-made interferons have been used as drugs, for example interferon-alpha for hepatitis B and C and some cancers, and interferon-beta for multiple sclerosis.
Word parts
Where does the word “interferon” come from?
- inter-
- betweenLatin inter
- -fer-
- to strikeLatin ferire, via Old French s'entreferir (to strike each other)
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Terms that go with it
- CytokineA cytokine is a small signaling protein released by cells, especially immune cells, that changes how other cells behave, grow or respond to infection.
- VirusA virus is a tiny infectious particle of DNA or RNA inside a protein coat that can multiply only by taking over the machinery of a living host cell.
- Innate immunityInnate immunity is the inborn, fast-acting set of body defenses that reacts to any invader in the same general way, with no prior exposure needed.
- Natural killer cellA natural killer cell is an innate lymphocyte that recognizes and kills virus-infected and cancerous cells without needing earlier exposure to them.
- Antiviral drugAn antiviral drug is a medicine that treats or prevents a viral infection by blocking a step in the virus's life cycle inside the host's cells.
- HepatitisHepatitis is liver inflammation, most often caused by a hepatitis virus but also by alcohol, toxins, some medicines or autoimmune disease.
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