Blood group MN precursors as human breast carcinoma-associated antigens and "naturally" occurring human cytotoxins against them.
Blood groups MN active substances were found in benign and malignant human mammary glands. However, the precursor T (Thomsen-Friedenreich) antigen, as determined with human sera, occurred in all cancerous breast tissues tested but not in the benign mammary glands. Anti-T antibody, which is present in all human sera, was severely depressed in 21.16% of 189 breast carcinoma patients, compared with 3.62% of 470 persons of similar age without cancer. Of 720 persons tested approximately 85% of those with severely depressed anti-T had carcinoma; their IgG, IgM and IgA concentrations were of normal range. A greater than 25%-90% increase in anti-T titer score was found in 65.6% of 32 patients bled 1-14 months after mastectomy for carcinoma as compared with 3.1% of 32 patients with breast biopsy who had no carcinoma. All differences in anti-T titer score changes reported are statistically highly significant. Injection of T antigen from human erythrocytes increased anti-T titer scores.