[Isolation of purified and concentrated human interferon from Namalwa cells]

The interferon produced in the cultured Namalwa cells was purified and concentrated according to the method of K. Cantell and S. Hirvonen developed for purification of leukocyte interferon. A preparation concentrated 500-fold had the antiviral activity of 10(6) IU/ml at a specific activity of 1-3 X 10(6) per 1 mg of protein. The amount of protein in the preparation was approximately 0.6 mg/ml, that of cell DNA less than 100 ng/ml. The experiments demonstrated that the virus inducer of interferon and possible contaminant viruses were removed on purification. The preparation had no oncogenic potency on inoculation of newborn Syrian hamsters, was harmless by intraperitoneal inoculation of mice and on multiple inoculations on rabbit eye cornea, was not toxic in cell cultures.