Characterization of monoclonal antibodies reactive with normal resting, lactating and neoplastic human breast.

Mouse monoclonal antibodies reacting with human mammary gland constituents have been generated and characterized in an attempt to raise breast- or breast-cancer-specific antisera. The immunogens used in these studies included fractionated human milk fat globule membrane, the human breast cancer cell line MCF7 and a crude membrane preparation derived from an axillary nodal metastasis from a patient with breast cancer. Of the antibodies obtained, 8 were characterized and found to bind to different structures in the normal breast. The antibody LICR-LON-LC28 recognizes secretory component and binds strongly to normal resting and lactating breast, but only focally to a minority of breast carcinomas. The antibodies LICR-LON-14.1 and 32.2 react strongly with the lactating breast and recognize kappa- and beta-casein, respectively. Caseins are not produced by breast tumors. The antibodies LICR-LON-TW19.5, H10A and 39.8 all react with carbohydrate epitopes and bind heterogeneously to normal resting breast luminal epithelium and cellular subsets of breast carcinomas. LICR-LON-59.2 and 19.2 react with normal breast myoepithelial cells and the basement membrane, respectively. LICR-LON-59.2 is unusual as a myoepithelial marker in that it stains cells in the majority of breast carcinomas. LICR-LON-19.2 shows extensive reactivity to tumor cell lines in culture but has no reactivity with carcinoma cells from breast biopsies.