A human monoclonal antibody derived from axillary lymph nodes of a breast cancer patient

A human hybridoma clone (A4-33) was established by fusion of human lymphoblastoid cells, HO-323, with lymphocytes of axillary lymph nodes obtained from a breast cancer patient. This clone has been stable, producing IgM for over 24 months. Enzyme-linked immunosorbent assay (ELISA) showed that monoclonal antibody A4-33 reacted strongly to MCF-7, and weakly to PANC-1 and HT-29, but not to other human malignant cell lines. The reactivity of A4-33 to MCF-7 was markedly reduced by treatment with periodate, but not affected or enhanced by neuraminidase or trypsin. Immunoperoxidase staining of normal human tissue sections showed that A4-33 reacted to acinar and ductal cells of the mammary gland and to ductal epithelial cells of the salivary gland, sweat gland, pancreas and bile duct. With malignant tumor sections, A4-33 reacted to breast cancer, pancreatic cancer and parotid cancer. These results suggested that A4-33 recognized the antigen which commonly exists on ductal epithelial cells of the exocrine gland.