Radioimmunoassay of circulating schistosome antigen with a radiation-immobilized monoclonal antibody : Preliminary results

A two-site immunoradiometric assay with a mouse monoclonal antibody to a circulating schistosome antigen was comparatively investigated using the monoclonal antibody either absorbed to microtiter plates (reference IRMA) or immobilized by several techniques. Radiation polymerization methods were carried out at Takasaki Radiation Chemistry Research Establishment, Takasaki, Gunma (I. Kaetsu, M. Kumakura), using 2-hydroxyethyl methacrylate monomers and 1 Mrad irradiation. A significant correlation was obtained with the reference IRMA and the assay using radiation polymerization-immobilized antibody (r = 0.94), although non-specific binding to the polymer discs was higher (x 10) than with microtiter plates. Immobilization of the monoclonal antibody onto polypropylene/polyethylene copolymer films grafted with methacrylic acid irradiated at 0.68 Mrads and treated with carbodiimide/N-hydroxysuccinimide, was carried out at the Dept of Bioengineering, University of Washington, Seattle, Washington (A.S. Hoffman, W.R. Gombotz, S. Uenoyama). A significant correlation (r = 0.90) was obtained with the reference IRMA. Non-specific binding was also higher than with microtiter plates (x 6). An important result was the increased shelf life of the immobilized reagent.