Presence of breast cancer antigens in uninvolved axillary lymph nodes.

Monoclonal antibodies which bind to breast cancer have been used to evaluate the detection of metastatic disease in axillary lymph nodes. Three monoclonal antibodies (H59, H71, and H72) were reacted with tissue sections of primary tumors and axillary nodes from 24 mastectomy specimens and four specimens from glandular mastectomies for benign disease. All three antibodies had been shown to react with subsets of normal and malignant breast tissue; did not bind erythroid, myeloid, or lymphoid tissue; and recognized antigens in paraffin-embedded tissue. The antibodies recognized cell surface antigens, and H59 and H72 bound to glycoproteins which are either sloughed or secreted. Primary tumors and tumors in lymph nodes from the same specimen were always bound by the same antibodies. Antibodies detected unrecognized microscopic tumor in nodes from one previously node-negative specimen and two specimens with positive nodes. This suggests that monoclonal antibodies may be useful for detecting metastatic breast cancer in nodes which by light microscopy are negative. Moderate binding of H59 and H72 antibodies to sinus histiocytes and perivascular cells was observed in all uninvolved nodes with sinus hyperplasia obtained from benign and malignant specimens. Thus, breast antigens can be identified in hyperplastic nodes in patients with no evidence of breast cancer. The antigens are detected predominately in the lymphoid sinuses and are bound to nonneoplastic cells. Therefore, breast antigens are regularly being processed and presented by normal lymphoid cells within the sinus. The binding of these monoclonal antibodies to axillary lymph nodes does not necessarily indicate the presence of metastatic disease. Dense binding to paracortical single cells was observed in tumor-containing lymph nodes and in uninvolved nodes obtained from mastectomy specimens with breast cancer. These cells are infrequent, and their number in an uninvolved node correlates with the pathological stage. They represent either binding to isolated lymphoid cells or metastatic tumor. Studies are under way to determine the origin of these cells.