Abstract
Production of interferon from cultured cells has required the presence of serum in the cell culture medium although it may be omitted during the period of interferon induction. In the system reported here a fully defined medium, free of protein, is employed. This permits the culture of the cells and all phases of interferon induction and release to be studied under completely defined conditions. The final product can easily be separated from its inducers to yield a preparation of high specific activity.
The LS strain of mouse fibroblasts, adapted to grow in suspension, has been under regular culture in this laboratory (Griffiths & Pirt, 1967; Birch & Pirt, 1969, 1970, 1971; Blaker & Pirt, 1971) in the protein-free medium (Birch & Pirt, 1970). The only polymer used in the medium is the uncharged polysaccharide methylcellulose.