Purification of Ornithine Decarboxylase‐inducing Factor from Cell‐free Ascites Fluid of Ehrlich Ascites Tumor and Its Characteristics

The ornithine decarboxylase‐inducing factor (ODC factor) was purified about 1,000‐fold in 42% yield from the ascites fluids of an Ehrlich ascites tumor by a combination of centrifugation and concanavalin A (ConA) treatment. A single ip injection of 0.5μg of the purified factor per mouse resulted in half‐maximum induction of liver ODC. The factor was found to be a trypsin‐ and chymotrypsin‐resistant, acidic glycoprotein (pi about 4.43) with a minimum molecular weight of about 70 kilodaltons, containing a disulfide bond(s) in its functional domain. It did not react with ConA. This factor induced retrodifferentiation of liver function, causing a marked increase of prototype M2 isozyme of pyruvate kinase. It reduced liver catalase activity, and also modified thyroid hormone metabolism, reducing the serum levels of T4 and T3. These results suggest that the ODC factor is multifunctional and induces many of the changes observed in a tumor‐bearing host.