The genes encoding type I interferons (IFNs), which include 14 IFN-? genes, one IFN-�� gene, one IFN-w (also known as IFN-? II1) gene, and a number of IFN-w pseudogenes, are clustered on human chromosome 9. Interferons-? and -�� are cytokines that are widely known to induce potent antiviral activity. IFN-? and -�� exert a variety of other biological effects, including antitumor and immunomodulatory activities and are increasingly used clinically to treat a range of malignancies, myelodysplasias and autoimmune diseases. IFN-w is antigenically different from human IFN-?, IFN-�� or IFN-?, but is a component of natural mixtures of IFN species produced by virus-induced leukocytes or Burkitt's lymphoma cells. The type I interferon receptor (IFN-?R) interacts with IFN-?, IFN-�� and IFN-w, and seems to be a multisubunit receptor.
