EXPRESSION OF TUMOR-ASSOCIATED ANTIGENS IN NORMAL, BENIGN AND MALIGNANT HUMAN MAMMARY EPITHELIAL TISSUE - A COMPARATIVE IMMUNOHISTOCHEMICALSTUDY

Breast carcinoma cells may express a variety of clinically relevant ep itopes, some of which are associated with aberrant glycosylation of MU C1 mucin molecules, as well as determinants which are commonly express ed on their normal molecular counterparts. The present investigation i s primarily an immunochemical analysis of MUC1 epitopes and other tumo ur associated antigenic determinants, as defined by their reaction wit h monoclonal antibodies and expressed in normal, benign and malignant epithelia. It was determined that malignant tissues of the breast expr essed MUC1 mucin, as well as the Le(y) hapten and CEA, at different in tensities, cellular distribution and patterns and percentages of posit ively stained cells. Conversely, benign tissues expressed a low intens ity of MUC1 which was restricted to apical cell surface membranes and lumen debris; a similar pattern was found in some normal breast sectio ns. It was concluded that MUC1 mucin exhibits heterogeneous antigenici ty (as defined by its reactivity with a panel of related anti-MUC1 mon oclonal antibodies) which is predominantly related to the progression of malignant disease. Le(y) is a marker of breast neoplasia, while CEA was found on only a small proportion of tumours. These immunohistoche mical findings are considered in the context of improving breast cance r diagnosis and therapy.