Characterization of monoclonal antibodies B1 and B3 that react with mucinous adenocarcinomas

B1 and B3 are two newly isolated monoclonal antibodies that react uniformly with the surface of many mucinous carcinomas of the colon, stomach, and ovary but with a limited number of normal tissues, among which are glands of the stomach, epithelia of the trachea and bladder, differentiated epithelium of the esophagus, and small bowel mucin. They also react uniformly with many human tumor cell lines, including MCF7, MDA-MB-468, and HTB20 (breast), A431 (epidermoid), HT29 (colon), HTB33 (cervical), and DU145 (prostate). Immunoprecipitation experiments indicate that B1 and B3 react with epitopes present on a large number of glycoproteins, ranging in molecular weight from greater than 200,000 to less than 40,000. Using a panel of 37 different carbohydrate residues attached to albumin to form neoglycoproteins, it was found that B1 reacts with Ley and H-type 2 and B3 reacts with Ley, di-Lex, and tri-Lex antigens. Thus, each antibody reacts with a distinct portion of a carbohydrate residue. Because of the limited reactivity of these antibodies with normal tissues, they merit evaluation in the treatment of cancer.