Characterization of sentinel node-derived antibodies from breast cancer patients.

Autoantibodies to breast and other cancers are commonly present in cancer patients. A method to rapidly produce these anti-cancer autoantibodies in the lab would be valuable for understanding immune events and to generate candidate reagents for therapy and diagnostics. The purpose of this report is to evaluate sentinel nodes (SNs) of breast cancer patients as a source of anti-cancer antibodies. Radiotracer lymphatic mapping in 29 patients with breast cancer confirmed the identity of the SNs which provided source cells for this study. Flow cytometry demonstrated ~28% of the MNCs were B cells and ~44% of the B cells were class switched memory B cells. EBV-induced proliferation of B cells yielded tumor binding antibodies from 3 wells per 1000 but cultures were too unstable for detailed evaluations. Hybridomas generated by electrofusion produced IgG (48%), IgM (34%) and IgA (18%) antibody isotypes which were screened for binding to a panel of breast cancer cells of the major molecular subtypes. Tumor lysate binding was observed in 28% of the hybridoma clones and 10% of these bound whole tumor cells with unique binding patterns. More detailed evaluation of selected clones showed binding to the patient's own tumor. SNs are removed from more than 100,000 breast cancer patients in the US per year. Samples from these lymph nodes represent a substantial opportunity to generate anticancer antibodies.