60 000 to 80 000 fold purer than the incubation medium in accordance with the present invention specific activity of interferon is modulated by addition of various levels of a controller protein such as human serum albumin to an eluate buffer used in immunoaffinity chromatography use of immunoaffinity chromatography is preferred because albumin binds to interferon and is carried through the immunoaffinity chromatography column along with the interferon and serves to both stabilize and define specific activity of the end product in addition the albumin is not separated from the interferon by this chromatographic method thus after treatment with immunoaffinity chromatography the final product consists of interferon albumin and eluate buffer the interferon having modulated specific activity as can be seen from fig1 which can be used to compare the weight volume percentage of human serum albumin or gelatin in the eluting buffer to specific activity of recovered interferon increasing the amount or percentage of human serum albumin in the eluting buffer causes a corresponding decrease in the specific activity of recovered interferon for example elution with 0 1 w v of human serum albumin in eluent buffer yields a specific activity of recovered interferon of approximately 6 3 u00d7 10 7 units mg elution with 0 5 w v of human serum albumin in eluent buffer yields a specific activity of approximately 9 4 u00d7 10 6 units mg elution with 0 1 w v of gelatin in eluent buffer yields a specific activity of about 3 2 u00d7 10 8 units mg and elution with 0 5 w v of gelatin in eluent buffer yields a specific activity of about 5 2 u00d7 10 7 units mg it is contemplated that other proteins may be added to the.