Differentiation antigens in fetal human pancreas. Reexpression in cancer.

An antiserum was raised against pancreatic extracts obtained from human fetuses under 5 months of gestational age. After absorption with adult tissues, this antiserum specifically recognized antigens located in the cytoplasm of fetal pancreatic acini. All of the examined pancreatic tissues, ranging from 3 to 5 months of gestational age, showed a strong positive reaction of most of the acinar cells. The number of stained acini and the staining intensity gradually decreased from 5 months onwards and by the 7th-8th month only a few cells remained positive. Adult pancreas was completely negative as were a variety of normal adult and fetal tissues. This antiserum also reacted with tumor structures in 18/18 pancreatic adenocarcinomas as well as with pancreatic acini in the vicinity of tumor. Primary carcinomas of the liver, large bowel, stomach, breast, urinary bladder, lung and other localizations did not react with this antiserum. In some cases of chronic pancreatitis (3/12) a reaction was observed in a few acinar cells. Immunoblot assay after polyacrylamide electrophoresis revealed, in both fetuses and tumors, two main antigens of approximately 60 kDa and 110 kDa relative molecular weight. Several minor components were also observed. These results suggest that our polyclonal antiserum defines a new group of oncodevelopmental antigens with high organ specificity.