Immunocytochemical distribution of a breast carcinoma associated glycoprotein identified by monoclonal antibodies.

A glycoprotein, BCA-225 (Mr 225,000-250,000), has been identified in cells and spent medium of clone 11 T47D breast carcinoma cells by three murine monoclonal antibodies, CU18, CU26, and CU46. The antigen was localized in paraffin sections of 167/178 (94%) Bouin's-fixed human breast carcinoma tissues and few other carcinomas (1/8 lung [squamous], 4/4 uterine cervix) in an intracellular pattern, whereas an apical or glycocalyx distribution was seen in several normal tissues, benign lesions, and malignant tumors. Although the immunocytochemical staining patterns observed with these antibodies have many similarities to those described with other previously reported monoclonal antibodies, notable differences include the lack of reactivity of CU18, CU26, and CU46 with lactating mammary gland and with gastrointestinal malignancies. BCA-225 binds to wheat germ lectin, not to concanavalin A, but monoclonal antibody binding does not appear to involve the carbohydrate component of the molecule. The frequency of the immunocytochemical detection of BCA-225 in breast carcinomas and its restricted distribution in other human tissues suggest considerable clinical potential for this antigen and its corresponding monoclonal antibodies.