Purification and characterization of carcinoembryonic antigen from GW-39, a xenografted human colonic tumor system.

Carcinoembryonic antigen (CEA) was purified from GW-39 human tumor xenografts in hamsters by immunoaffinity chromatography. Binding of the antigen to immobilized monoclonal antibody provided a high degree of purification of CEA in a single step. A recovery of 79% and a 750-fold purification were obtained. The purified CEA has a molecular size of 180 kilodaltons, an isoelectric point of 4.4, and a specific activity of 0.94. About 73% of the radiolabeled GW-39 CEA reacted with goat anti-CEA serum. The amino acid and carbohydrate compositions of the GW-39 CEA were comparable to those of CEA preparations from other sources.