Human interferon omega - a review

Abstract

A single functional gene in the human genome codes for interferon omega (IFN-ω), a monomeric glycoprotein distantly related in structure to IFN- α and IFN-β, but unrelated to IFN-γ. IFN-α is secreted by virus-infected leukocytes as a major component of human leukocyte interferon. The human class IIFN receptor complex which mediates the biological activity of IFN-α and IFN-β also binds IFN-ω. Its specific activity in a standard in vitro antiviral assay system is 4 × 10⁸ U mg^-1; potent antiviral activity against several DNA and RNA viruses has been demonstrated. IFN-ω inhibits proliferation of a variety of tumor cell lines in vitro. The protein stimulates natural killer cell activity, enhances expression of major histocompatibility complex class I (but not class II) antigens and inhibits proliferation of lymphocytes stimulated with mitogens or allogeneic cells. IFN-a is unrelated to IFN-α, -β and -γ in its antigenic properties, as it does not cross-react with antisera or monoclonal antibodies in immunoassays or antiviral neutralization bioassays. Antibodies induced in patients by long-term IFN-α2 therapy that block IFN-α2 activity do not inactivate IFN-ω. As IFN-ω, like other human IFNs, has a species-restricted biological activity, evaluation of its therapeutic potential will have to await clinical trials.