Antigenic cross-reactivity between adenocarcinoma of the breast and fibrocystic disease of the breast.

Peripheral lymphocytes obtained from 12 of 13 patients who had fibrocystic disease (FCD) of the breast were specifically cytotoxic to breast adenocarcinoma cells, as measured in vitro by the microcytotoxicity test. Sera from 6 women with active FCD or metastatic breast cancer could specifically block the cytotoxicity of lymphocytes from either population of patients against cancer cells. This implied extensive antigenic cross-reactivity between benign and malignant hyperplastic disease of the breast. Sera from 4 individuals clinically free of FCD or breast fibroadenoma (FAD) neutralized the blocking activity in the sera of patients with metastatic breast cancer. Patients "cured" of FCD or FAD represented a pool of potential plasma donors for immunotherapy of recurrent breast cancer.