Two-site immunochemiluminometric assay for human α1-fetoprotein

Abstract

In this two-site immunochemiluminometric assay for human α1-fetoprotein, acridinium ester-labeled monoclonal antibodies are used that have an average incorporation ratio of 0.3 mol of acridinium ester per mole of antibody. The solid-phase antibody consists of sheep anti-α1-fetoprotein IgG covalently coupled to a diazonium derivative of reprecipitated aminoaryl cellulose. The assay involves a 1-h incubation after the simultaneous incubation of labeled and solid-phase antibodies. The subsequent quantification time is 10 s per tube. The assay has a working range of 20 to 246 kilo-int. units/L for CVs ≤ 10% and a sensitivity of detection of 1.3 kilo-int. Units/L. Experiments with monoclonal antibodies labeled to an average incorporation ratio of 2.8 mol of acridinium ester per mole of antibody suggest that assay sensitivity increases with increased specific activity. α1-Fetoprotein concentrations in the sera of pregnant women at 14-20 weeks of gestation, as measured by the present assay, agreed with the results of a conventional radoimmunoassay.