Expression of basal and luminal epithelium-specific keratins in normal, benign, and malignant breast tissue.

We characterized the subclass-specific keratins in the epithelium of normal, benign, and malignant breast tissue. Monoclonal antibody 34BE12 stained luminal as well as basal epithelium in normal and benign specimens and all tumor cells in malignant specimens. Antibody 312CS-1 reacted only with basal cells, and antibody LE61 reacted only with luminal cells in the normal and benign specimens. In 34 of 36 breast carcinomas examined, the basal and luminal cell-specific antibodies showed complementary patterns of reactivity, while in the remaining 2 specimens, neither antibody was reactive. The findings reported in this study demonstrate that expression of subclass-specific keratins is mutually exclusive not only in normal and benign mammary specimens but also in breast carcinoma. These findings suggest a role for epithelial subclass-specific antibodies in the histogenetic and prognostic subclassifications of breast carcinoma.