The expression of ABH and Y blood group antigens in benign and malignant breast tissue: the preservation of the H and Y antigens in malignant epithelium.

The ABO(H) and Y antigen status of epithelial cells from 45 breast carcinomas, 14 benign breast lesions and 7 normal breasts have been assessed using an indirect immunoperoxidase histochemical assay and a series of blood group specific monoclonal antibodies. All 20 A, AB and B group tumours had lost the A and B isoantigens, 13 of these tumours were however found to express H and Y antigens. Of 25 group O tumours 17 expressed the expected H and Y antigens. These findings were not dependent on the histological nature or the invasive characteristics of the tumour. Similar results were obtained when 28 metastases from breast carcinomas were examined, the H and Y antigens being identified in the tumour elements in 24 lymph nodes while we failed to identify either the A or B antigens. The development of breast malignancy appeared therefore to correlate best with the deletion of A and B glycosyl transferases. Normal breast tissue consistently expressed the expected blood group isoantigens. Areas of benign breast disease showed a more varied pattern of antigen expression. Seven of 14 lesions lacked ABH antigens, the loss of blood group structures could not however be correlated with any specific histological features and was not limited to the loss of A and B substances.