Pancreatic oncofetal antigen (POA) purified by us has been detected in sera of patients with
carcinoma of the pancreas by the micro-Ouchterlony method. In an attempt to improve the sensitivity and clinical usefulness of the serum POA assay, we established an
enzyme immunoassay for POA and reported the results with this method. In this study, we investigated serum POA levels in
pancreatic cancer and other diseases. The tissue localization of this POA in the pancreas was also studied. For the establishment of the
enzyme immunoassay, an anti-POA-F(ab')2 fragment prepared from absorbed antiserum was conjugated with
beta-D-galactosidase. The solid-phase "sandwich" principle was used. The normal upper limit of the serum POA level was defined as 400 units/ml. Among 60 patients with
pancreatic cancer, 44 had elevated levels (73.3%). Of 22 cases with
chronic pancreatitis, 4 had elevated levels (18.2%). In malignant diseases other than
pancreatic cancer, elevated levels of serum POA were seen in 17.6% to 48.5% of the patients, most of whom had only slightly elevated levels. These results indicate that
enzyme immunoassay for POA is clinically useful for making a diagnosis of
pancreatic cancer. Immunoperoxidase staining showed POA to be found at the apical surface of ductular cells in fetal pancreas, at the
luminal surface of glandular structures in
pancreatic cancer tissue, and also at the
luminal surface of the small duct in normal pancreas. Thus it is suggested that a high level of serum POA in patients with
pancreatic cancer is derived from
pancreatic cancer tissue.