Purification, partial characterization, and clinical evaluation of a pancreatic oncofetal antigen.

Abstract

Abstract This paper describes the purification and partial characterization of a putative pancreatic oncofetal antigen. Pancreatic oncofetal antigen is a glycoprotein with a molecular weight between 800,000 and 900,000, which migrates in the α 2 - to β-region on electrophoresis. It is found in fetal pancreas and pancreatic cancer tissue, but it is not found in normal adult pancreas. Highly purified material migrated as a single band on polyacrylamide gel electrophoresis and immunized rabbits to produce monospecific antibody without absorption. Pancreatic oncofetal antigen is clearly different from carcinoembryonic antigen, other known tumor-associated antigens, acutephase reactants, and normal serum proteins. In addition, a quantitative rocket immunoelectrophoresis assay sensitive enough to detect pancreatic oncofetal antigen in the serum of most patients was developed and used to monitor the purification of pancreatic oncofetal antigen and to evaluate its clinical application. Assays for pancreatic oncofetal antigen were carried out on three panels of sera; one was collected at The University of Chicago, and two were supplied by the Mayo-National Cancer Institute Serum Plasma Bank. The results demonstrate that pancreatic oncofetal antigen is found in the sera of most individuals; however, by far the highest absolute levels and the highest frequency of elevated levels were found in sera of patients with carcinoma of the pancreas. Elevated levels of pancreatic concofetal antigen were also observed in the serum of some patients with carcinoma of the lung, stomach, colon, biliary tract, and breast as well as in the serum of some pregnant women and other individuals with certain benign conditions. The spectrum of patients who have elevated levels of pancreatic oncofetal antigen in their serum is quite different from that found with carcinoembryonic antigen or other known tumor markers. Serial assays were performed on the sera of several patients with cancer of the pancreas; the results suggest that measurement of pancreatic oncofetal antigen may be valuable in monitoring the course of cancer of the pancreas.