Isolation from patients with breast cancer of antibodies specific for antigens associated with breast cancer and other malignant diseases.

Antibodies were specifically purified, with the use of pleural fluid antigens entrapped in a polyacrylamide gel as immunoadsorbent, from a pool of sera from patients with breast cancer and from the pleural effusion of an individual patient. The purified antibodies were radioiodinated and tested for capacity to bind to the pleural fluid adsorbent. Binding of the radiolabeled antibodies was inhibited by many of the sera from women with breast cancer to a much greater extent than by sera of healthy women. With purified antibodies originating from the serum, 52% of the breast cancer sera and 16% of sera from patients with other malignancies were more inhibitory than were 95% of the sera of healthy women. In the tests with antibodies eluted from pleural fluid, 24% of the breast cancer sera and 25% of the sera from patients with other neoplastic diseases were more inhibitory than were 95% of the normal sera. We concluded that sera of patients with breast cancer may contain antibodies against antigens associated with breast cancer as well as additional antibodies against antigens that are also found in patients with other neoplastic diseases or in normal individuals. Individual breast cancer sera may inhibit binding of the labeled antibodies against breast cancer owing to their content of antibodies, antigen(s), or both.