Comparison of enhanced chemiluminescence and microparticle enzyme immunoassay for the measurement of hepatitis B surface antibody

Two commercially available immunoassays for the quantitative measurement of antibodies to hepatitis B surface antigen (HBsAg) were compared. The Amerlite enhanced chemiluminescence assay (ECL), which utilizes capture antigen obtained from HBsAg-positive donors bound to microtitre wells, was compared with the Abbott Laboratories microparticle enzyme immunoassay (IMx), which uses a recombinant antigen coated on to microparticle carriers. A total of 310 specimens, 116 from naturally infected patients (group A), 93 from patients vaccinated with a human plasma-derived vaccine (group B) and 101 patients vaccinated with a recombinant vaccine (group C), were tested in both assays undiluted and diluted 1:11. Samples that showed discordant results were also tested in a conventional quantitative enzyme immunoassay (Sorin). The results show significant differences in the level of anti-HBsAg in patient sera using the two technologies. In general, IMx gave significantly higher values than ECL for all three patient categories tested. These differences may lead to conflicting reports being issued by laboratories who change their assay system or when a sample from one patient is tested by different laboratories using different assays.