Two-Site Immunochemiluminometric Assay for Human a1-Fetoprotein

In this two-site immunochemiluminometric assay for human a1-fetoprotein, acndinium 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-a1-fetoprotein IgG covalently coupled to a diazonium derivative of reprecipitated aminoaryl cellulose. The assay involves a 1-h incubation after the simultaneousincubationof labeled and solid-phaseantibodies. The subsequentquantificationtime is 10 s per tube. The assay has a working range of 20 to 246 kilo-mt. units/L for CVs 10% and a sensitivity of detection of 1.3 kilo-mt. 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. a1-Fetoprotein concentrations in the sera of pregnant women at 14-20 weeks of gestation, as measured by the present assay, agreed with the resultsof a conventionalradioimmunoassay.