Monoclonal antibodies to tumor-associated antigens.

Experience is described in applying monoclonal antibodies (Mabs) to immunohistology, epitope analysis on antigens, and radioimmunoassay. The antibodies (provided by international laboratories) used in the experiments described were directed to the mouse mammary tumor virus, a cell surface component of melanoma cells, several proteins of the human milk fat globule membrane (as markers for cell differentiation in breast cancers) as well as to Carcinoembryonic Antigen (CEA). At least three antigenic determinants were detected on CEA, which appeared as being expressed in different quantities in those organs producing CEA-like molecules (lung, spleen, normal colon mucosa, liver). By means of an inhibition radioimmunoassay for CEA, evidence was obtained that in the lung more than one cross-reacting antigen might exist, one of them of high molecular weight (about or more than 200,000 daltons). In immunoperoxidase tests, several antibodies to CEA were seen to react with pulmocytes and bronchus glands. Summarizing the experience, it is concluded that thorough characterization of monoclonal antibodies by more than one method is a prerequisite to their use for analytical or diagnostic purpose.