Description_x000D_ Biochem/physiol Actions_x000D_ Cytokine with anti-viral, anti-proliferative, immunoregulatory, and proinflammatory activities. Type I Interferons are a closely related family of 165-172 amino acid proteins that are produced by leukocytes (α subtypes), fibroblasts (β subtypes), lymphocytes (ω subtypes) and ruminant embryos (τ subtypes). Interferon induces a variety of effects on target cells including antiviral, antiproliferative and immunomodulatory activities._x000D_ Packaging_x000D_ Minimum 1x105 units/vial._x000D_ Physical form_x000D_ Solution in phosphate buffered saline containing 0.1% bovine serum albumin._x000D_ Analysis Note_x000D_ The biological activity is determined in the cytopathic effect inhibition assay using mouse L929 cells with encephalomyocarditis virus. The cytopathic effect of 50% is produced with approximately 1 unit/ml interferon. The units are determined with respect to NIH international standard reference for mouse interferon α.