Improvement of tumor cell detection using a pool of monoclonal antibodies.

It has been proven that monoclonal antibodies which are not strictly tumor specific may be useful in clinical oncology for diagnosis and in in vitro therapy. These applications, however, are hampered by the heterogeneous expression on tumor cells of the epitopes defined by the majority of monoclonal antibodies produced so far. The use of combined monoclonals could complement their antitumor specificity and solve the problem. In this perspective we selected nine monoclonal antibodies directed against different antigens of primary and metastatic breast cancer cells. The reactivity of the pool of these nine monoclonals versus a single antibody (MBr1) was determined by immunofluorescence on tumor cell lines, on frozen sections of various carcinomas, and on live cells obtained from malignant effusions. The results obtained with the pool, compared to those using MBr1 alone, showed a remarkable increase in the number of immunopositive breast and other carcinomas and the number of immunopositive cells within each positive tumor. In fact, the percentage of immunoreactive breast carcinomas increased from 79% to 100%, and the percentage of immunoreactive carcinomas of other sites from 61% to 89%. In addition, the number of positive breast carcinomas showing 100% immunoreactive cells increased from 5% with MBr1 to 71% when the pool was used.