A pancreatic oncofetal antigen (POA): its characterization and application for enzyme immunoassay

Abstract

We investigated the usefulness of enzyme immunoassay (EIA) for pancreatic oncofetal antigen (POA). The crude POA isolated from POA-positive ascitic fluid of patients with pancreatic cancer was injected into rabbits to raise anti-POA serum. The adsorbed antiserum was used for EIA as anti-POA serum. For the establishment of EIA system for POA, anti-POA-Fab' fragment was conjugated to beta-D-galactosidase from Escherichia Coli. Normal subjects (205 controls) and 132 patients (47 with pancreatic cancer, 22 with chronic pancreatitis, and 63 with other malignant disease) were surveyed. The standard serum from patient M with pancreatic cancer was used in quantitatively determining serum POA levels; value was expressed arbitrarily as 1000U/ml. Normal upper limit of POA was defined as less than 400U/ml (mean + 2SD of normal subjects). POA level higher than normal was observed in 72% of patients with pancreatic cancer, 23-44% of patients with other malignant diseases, and 18% of patients with chronic pancreatitis. The susceptibility of the isolated POA to several enzymes and chemical reagents was also studied. These results suggest the usefulness of EIA for POA in diagnosis of pancreatic cancer.