A second-generation enzyme immunoassay for detection of antibodies to IFN-alpha

We have developed a solid-phase enzyme-linked immunoassay (EIA) for detecting antibodies to interferon-alpha2 (IFN-alpha2) in serum or plasma. In this assay, based on the sandwich principle, the capture antigen, IFN-alpha2, is covalently bound to the wells in 96-well plates. This novel procedure offers considerable advantages over the antigen binding by passive adsorption used in most previous EIA. Specific antibodies present in clinical specimens bind to the anchored antigen and are detected by adding peroxidase-labeled IFN-alpha2 and a peroxidase substrate mixture. The resultant color is a function of the concentration of antibody in the sample. The assay has proved to be convenient, precise, and reproducible and can detect as little as 1-5 ng/ml of specific antibody IgG.