An antibody class capture technique is used. This involves the dilution of the sample and the simultaneous reaction of IgM in the diluted sample with biotinylated mouse monoclonal antihuman IgM antibody. The immune complex is captured by streptavidin on the wells. Unbound materials are removed by washing. Horseradish peroxidase (HRP)-labeled mouse monoclonal anti-hepatitis B core (anti-HBc) IgM antibody, which has been complexed with recombinant HBc antigen (conjugate), is then captured by anti-HBc specific IgM bound to the wells. Unbound material is removed by washing.
The bound HRP conjugate is measured by a luminescent reaction. A reagent containing luminogenic substrates (a luminal derivative and a peracid salt) and an electron transfer agent is added to the wells. The HRP in the bound conjugate catalyzes the oxidation of the luminal derivative, producing light. The electron transfer agent increases the level and duration of the light produced. The light signals are read by the VITROS ECi System. The amount of HRP conjugate bound is indicative of the concentration of anti-HBc IgM present in the sample.(Package insert: VITROS Anti-HBc IgM assay, Ortho-Clinical Diagnostics, Raritan, NJ)