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Mechanism of interferon biological effects Volume 3, issue 4, Juillet - Août 1997

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Interferons (IFN) are a family of proteins secreted by almost all cellular types. All IFNs have the capacity to induce an antiviral state. IFN are also intercellular mediators involved in the modulation of cell proliferation and differentiation, in the activation of NK cells and cytotoxic T lymphocytes. They display many immuno-modulating properties, and have anti-tumor effects. IFN play an essential role in the regulation of HLA expression. According to their antigenic and molecular properties, IFN are divided in two major classes : type I IFN : IFN-a, IFN-b, IFN-w and IFN-t, and type II IFN : IFN-g. As many cytokines and growth factors, the effect of IFN are initia- ted through their interaction with specific cell surface receptors. Type I IFN share a common receptor different from that of type II IFN. Binding of IFN to their specific receptors leads to the activation of associated tyrosine kinases of the Janus kinase family (Jak). The latent cytosolic transcription factors (STAT) are then phosphorylated, translocated to the cell nucleus where they bind to enhancer elements of inducible target genes.