Abstract
Hybrid plasmids containing the mouse dihydrofolate re-ductase (dhfr) and a human interferon (either IFN-α5 or IFN-γJO coding sequence under the control of viral promoters were trans-fected into dhfr Chinese hamster ovary (CHO) cells. Dhfr+ colonies produced IFN at 10-1000 units-ml–1-day–1. Clones selected in methotrexate had a 20-50-fold increase in the IFN-a5 and dhfr DNA and mRNA content and secreted IFN at 20,000-100,000 units.ml–1.day–1”1. SDS-polyacrylamide gel electrophoresis of partially purified 35s-HuIFN-γ from CHO cells showed a multiplet of labeled bands with a mobility corresponding to 22,400 to 23,400 daltons which was absent in the supernatants of non-transformed CHO cells. The higher apparent molecular weight of human IFN-Jγ from CHO cells as compared to that of human IFN-γ from E.coli (about 18,800) suggests that the former was glycosylated.