A radioactive antibody binding-inhibition assay, for the detection of cell-membrane related antigens in body fluids.

Antisera raised in rabbits against glutaraldehyde-fixed human breast cancer cells contain antibodies to human cell membrane components, as determined by immunofluorescence. Adsorption of such antisera onto polymerized human serum, followed by acid elution, yields purified antibodies reacting with human cell surface antigens, indicating that membrane related antigens are present in the serum. The purified antibodies were radioiodinated and shown to bind to an immunoadsorbent prepared by entrapping in a polyacrylamide gel pleural exudate of breast cancer patients. The specificity of the binding was confirmed by inhibition experiments. Data are presented demonstrating that at least some of the antibodies reacting in this radioimmunoassay are directed against antigens related to cell surface components.