Blood group MN antigens and precursors in normal and malignant human breast glandular tissue.

Blood group M and N active substances were demonstrated in human mammary gland tissue in both benign and malignant lesions. The precursor T (Thomsen-Friedenreich) antigen occurred only in cancerous tissue, where it was found regularly in the 15 gross cancers tested. The precursor Tn antigen also was found regularly in cancerous breast tissue; Both antigens were reactive in breasts with in situ carcinoma. The T antigen was not demonstrable in the 6 benign mammary glands studied; similarly, the Tn antigen was unmasked by sialidase treatment of healthy breast tissues. Anti-T antibody, present in all human sera, was severely depressed in many breast cancer patients compared to controls.