Isolation and characterization of subspecies of murine interferon alpha

Interferon produced by mouse L-929 cells by incubation with poly(rI).poly(rC) is known to be composed of a mixture of MuIFN-alpha and MuIFN-beta. The alpha component was separated from the bete species by affinity chromatography over a monoclonal anti-MuIFN-beta agarose column and partially purified by gel filtration. MuIFN-alpha, prepared by this method was separated into at least five subspecies by chromatofocusing. The approximate pI values of these components are greater than or equal to 7.5, 6.5, 6.2, 5.9 and 5.6, respectively. Component 3 (pI 6.2) was the most prominent subspecies present in our MuIFN-alpha preparations, representing 40 to 50% of the total antiviral activity. Component 1 (pI greater than or equal to 7.5) which accounted for about 5% of the antiviral activity on mouse cells, differed in some properties from the other interferon subspecies. It showed a relatively high antiviral activity on heterologous cells and it was eluted from a Sephadex column after the other alpha subspecies. Furthermore, it showed a diminished binding to heparin as compared to the other MuIFN-alpha subspecies, indicating a lower affinity for polynucleotides.