“Sandwich” Solid Phase Radioimmunoassay for the Quantitative Deteriminaton of Human Immunoglobulins

Abstract

This report describes a sensitive, relatively simple solid-phase “sandwich” radioimmunoassay and its application to the quantitative measurement, and antigenic analysis, of immunoglobulin components, using antisera to the heavy chains of IgG, IgA and IgM. With this technique, the solid-phase, consisting of disposable plastic tubes or commercial isothiocyanate-substituted plastic discs, is sensitized by sequential binding of pure antigen to the plastic polymer, antibody to the antigen, and unlabeled or labeled antigen to the antibody. The quantitative binding of labeled antigen by the sandwich-sensitized solid-phase is greatly enhanced as compared with tracer binding by solid-phase polymer coated only with antibody. The sandwich technique allows quantitation of immunoglobulins in the nanogram to microgram range, and is applicable to a variety of immunologic studies where this range of sensitivity is required.