Chromatographic behavior, purification, and properties of mouse BCG-induced gamma interferon

Mouse gamma antigen-induced interferon (IFN) was produced in vivo by injecting PPD into BCG-sensitized mice. The IFN activity present in the serum was partially purified by adsorption on silicic acid and elution with buffer containing ethylene glycol, followed by chromatography of the eluate on Blue-Trisacryl. This method yielded IFN preparations with a specific activity of 1.5 x 10(5) mu/mg protein (10,000-fold purification). BCG IFN showed high affinity for polynucleotides and apparent hydrophobicity, two characteristics which allowed it to bind to Poly I agarose and Phenyl Sepharose, respectively. The chromatographic behavior of BCG IFN on Con A Sepharose indicates that BCG IFN is glycosylated. However, binding of the antiviral activity to the lectin column was only possible when purified IFN was used for chromatography. Although the purification method described here allowed purification of the antiviral activity as a major fraction, molecular heterogeneity was detected under certain chromatographic conditions. Two fractions with different molecular weights of 27,000 and 56,000, respectively, were always obtained by sieving purified BCG IFN on Sephacryl S 200.