Serum alpha-feto-protein. VI. The radio-immunoassay evidence for the presence of AFP in the serum of normal people and during pregnancy.

Abstract

A radioimmunoassay technique used to assay alpha fetoprotein (AFP) is presented. The procedures involved in the preparation of 125I-labelled AFP of sheep antirabbit gamma globulin and rabbit anti-AFP and of immunoabsorbents are described. The radioimmunoassay system itself is discussed as is the radioimmunoassay of AFP and the sensitivity of the technique. Finally the method used and results obtained in a determination of AFP in normal and pregnant serum are set forth. The large quantities of AFP in pregnant sera (at least 100 ng/ml) are assumed to originate in the fetus. Normal levels are in the region of 15 ng/ml. The source of normal AFP is thought to be related to normal cellular turnover and synthesis of AFP-like proteins may be a stress reaction of the liver. Further reports will be made on the overlap of raised AFP levels seen among apparently healthy people who live in highrisk regions sick people and liver cancer patients.