Immunologic Studies on a Pancreatic Oncofetal Protein 2

Abstract

Immunization of rabbits with a human fetal pancreas extract produced precipitating antibody against an antigen present only in fetal pancreas and extracts of human pancreatic carcinoma. Pancreatic oncofetal protein (POP) migrated on immunoelectrophoresis in the α₁-α₂ region, thus making possible its detection by counterimmunoelectrophoresis. POP was found in the 12,000×g supernatant of fetal pancreas and could be precipitated with (NH₄)₂SO₄ at concentrations between 30 and 45%. The antigen was partially purified by consecutive centrifugation at 12,000×g, 40% (NH₄)₂SO₄ precipitation, and ion-exchange chromatography. Treatment of the POP with trypsin completely abolished its antigenic activity; this suggested that the antigen was a protein or a moiety closely associated with protein.