title: Three-site sandwich radioimmunoassay with monoclonal antibodies for a sensitive determination of human alpha-fetoprotein.
abstract: Utilizing monoclonal antibodies against human alpha-fetoprotein, 3 distinct antigenic determinants were identified. These antigenic determinants, provisionally designated a, b and c, were arranged in such a manner that the binding of one determinant with the corresponding antibody did not inhibit, or only barely inhibited the binding of antibodies directed to the other 2 determinants. Monoclonal antibodies with 3 different specificities were, therefore, applied to develop a sandwich-type solid-phase radioimmunoassay of the antigen in which wells were coated with anti-a, and radiolabeled anti-b together with radiolabeled anti-c was employed to detect the bound antigen. The 3-site sandwich radioimmunoassay involving 3 different determinants gave a higher sensitivity than 2-site assays in which only anti-b or anti-c was employed as a radiolabeled reagent, because the radioactivity of the 2 labeled antibodies was added on the antigen bound to immobilized anti-a.
mesh_terms: D000911:Antibodies, Monoclonal; D000918:Antibody Specificity; D000936:Antigen-Antibody Complex; D006801:Humans; D011863:Radioimmunoassay / Q000379:methods*; D000509:alpha-Fetoproteins / Q000032:analysis*
chemical_list: D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D000509:alpha-Fetoproteins