Production and Purification of Human Leukocyte Interferon

Interferon production in human leukocyte suspensions induced by Newcastle disease virus is significantly affected by the pH of the culture. The optimal pH for interferon production is higher than the physiological pH level. Human leukocyte interferon has at least three types of surface charge as demonstrated by DEAE‐cellulose column chromatography. The molecular wight of these three types of interferon, as measured by gel chromatography on several kinds of Sephadex is equally 25 000. The main fraction of human leukocyte interferon was purified approximately 1400‐fold by a sequence of procedures which involved ammonium sulfate salting out, CM‐ and DEAE‐cellulose column chromatography and gel filtration on Sephadex G‐50. Human leukocyte interferon of a high specific activity of about 2 130 000 units/mg of protein was thus obtained.