Abstract: The present invention provides a method to achieve radioisotopic localization at tumor sites, i.e., a method of enhancing radiolabeled ligand localization to a tumor in an individual in need of such treatment, comprising the steps of: transducing said tumor with a gene encoding a membrane expressed protein unique to said tumor; and administering to said individual a radiolabeled ligand which specifically binds to said protein. The use of gene therapy technology to induce expression of high affinity membrane molecules/receptors can enhance the specificity of radioisotope localization while the use of radioactive isotopes with the ability to deliver radiation damage across several cell diameters will compensate for less than perfect transduction efficiency.

Abstract: Hybrid-myeloma cells which produce monoclonal antibody specific to the .beta. subunit of human chorionic gonadotropin and methods of use of the monoclonal antibody.