Immunoassay in the presence of water-soluble polymers

To overcome the adverse consequences of antibody immobilization (impairment of the antigen-binding parameters) the interaction of a number of antigens with both soluble and covalently immobilized antibodies in the presence of water-soluble polymers has been investigated. Incorporation of some water-soluble polymers (Ficoll, Dextran) into the assay mixture was shown to substantially increase the antigen-binding capacity of both soluble and immobilized antibodies. The use of dextran T70 enhanced the sensitivity of competitive radioimmunoassays for CEA and beta 2-microglobulin 3-4-fold. This procedure may be also applied to shorten the incubation period when performing an assay.