Radioimmunoassay of alpha-fetoprotein, with special reference to iodination and purification techniques.

We report a relatively simple and convenient method for iodinating human alpha-fetoprotein and for purifying the 125I-labeled material. The label is incorporated into human alpha-fetoprotein enzymatically by use of lactoperoxidase. Before each assay the labeled material is purified over two successive short columns: Sepharcryl S-200 Superfine and cellulose. This procedure removes both free iodine and "damaged" fetoprotein. With the purified material we developed a sensitive and reliable radioimmunoassay for alpha-fetoprotein in serum and amniotic fluid.