A New Carcinoembryonic Protein Characterized by Basic Property

Abstract

A new human fetal antigen, common to several types of carcinomas was found in fetal serum and fetal gut extract. Because this antigen was shown to have an isoelectric point of 9.3, it has been designated basic fetoprotein (BFP). BFP was purified from ascites of a patient with hepatoma by the techniques of QAE‐Sephadex A‐50 chromatography. affinity chromatography. isoelectrofocusing and gel filtration. The purified BFP had a γ‐mobility by electrophoresis and a molecular weight of 124,000 by SDS polyacrylamide gel electrophoresis. Monospecific anti‐BFP was prepared by immunizing a rabbit with the purified BFP.A radioimmunoassay was developed based on a coprecipitation‐inhibition technique using 125I‐BFP and monospecific anti‐BFP. BFP in human serum was determined by the radioimmunoassay. BFP was detected in sera from all normal subjects. Serum BFP levels were lower than 100 ng/ml in 100 out of 101 normal subjects, lower than 200 ng/ml in 180 out of 204 patients with non‐malignant diseases and higher than 200 ng/ml in 94 out of 251 patients with malignant neoplasms. The determination of BFP in serum was demonstrated to be useful for the diagnosis of various carcinomas.