Determination of alpha-fetoprotein by a new paper disc radioimmunoassay of the sandwich type.

Determination of alpha-fetoprotein (AFP) in the 1- to 500-mug/litre range has been shown to be of diagnostic value in a variety of clinical settings, in particular, in prenatal diagnosis and the monitoring of pregnancies. A modified paper disc sandwich radioimmunoassay (sandwich RIA) is described which meets the essential criteria for large-scale assaying for AFP. The sandwich RIA is based upon anti-AFP antiserum, which is available commercially, and thus purified AFP is not essential. The sandwich RIA (1) is simple to run and gives results within 24 h; (2) has a comparatively broad range of sensitivity; (3) requires no apparatus other than a gamma-scintillation counter, and (4) has an acceptable level of accuracy. We have used the described sandwich RIA for AFP in routine obstetrical practice for over 2 years. Our experience, encompassing more than 15,000 samples, has been most satisfactory.