Morphologic assessment of reactivity to monoclonal antibodies generated against breast cancer cells in mammary tissues removed for clinical dysplasia or cancer.

Monoclonal antibodies B 6.2, B 72.3 and B 1.1, reactive against tumor-associated antigens of human breast cancer, have been tested on histologic sections of paraffin blocks from 49 cases of breast cancer and from 13 cases of mammary dysplasia. The results have shown that: (a) the three monoclonal antibodies recognize different antigenic determinants of the cancer cells; (b) monoclonal antibodies B 6.2 and B 1.1 recognize antigens which are frequently expressed in cancer cells; (c) the antigen recognized by monoclonal antibody B 72.3, at the concentrations used, is less frequently expressed in tumors, while it seems to be selective for the apical cell border and luminal secretions of apocrine metaplastic lobules or cysts occurring in mammary dysplasia; (d) intracytoplasmic expression of the antigens is observed only in cancer cells, with rare exceptions; (e) tumor cell populations are heterogeneous in respect to the expression of the antigens detected by the monoclonal antibodies tested; (f) the antigens detected are unrelated to the tumor histotype; (g) the frequency of axillary lymph nodal metastases is not influenced by the presence or intensity of antigenic expression in the primary tumors; but (h) in metastatic tumor cell populations the antigenic expression is higher than in primary tumors. This fact suggests some relationship between tumor metastatization and the expression of antigens recognized by the monoclonal antibodies tested