Abstract
Summary Human leucocyte interferon (HuLeIF) was purified by a series of techniques involving precipitation, gel filtration, Cu-chelate-, blue dextran- and antibody-affinity chromatography. The two major species of HuLeIF were identified in SDS-PAGE as two clearly separable and stainable proteins representing 85% of the biological activity. Three more species of HuLeIF representing 15% of the biological activity were also demonstrated. The specific activity of pure interferon proteins was approx. 109 IFU/mg protein. Recovery was about 50% and the purification factor exceeded 350000. All five species of HuLeIF had definite anticellular activities when tested with Daudi cells (inhibition of thymidine uptake).