Automated two-site immunoradiometric assay of human alpha-fetoprotein in maternal serum.

Immunoassays of alpha 1-fetoprotein in maternal serum are now in widespread use as a means of antenatal detection of neural tube defects. For population screening to be effective the initial test must be capable of promptly producing reliable results. We describe an automated two-site immunoradiometric assay based on 125I-labeled antibodies and cellulose-coupled antibody, with which up to 100 patients' samples can be assayed in 3 h. The assay is precise, and results obtained agree closely with those produced by conventional radioimmunoassay procedures.