Red blood cell cold agglutinins and B lymphocyte cytotoxins in breast cancer sera.

Cytotoxic activity towards B-lymphocytes in sera from individuals with breast carcinoma was related to red blood cell cold agglutinin levels and IgM values. The control group consisted of 32 females with a similar age distribution. Significant increases in red blood cell cold agglutinin levels were found in the group of cancer patients and the group with the histological category of mucin-producing carcinoma with lymphocyte cytotoxins (p less than 0.025, respectively), in comparison to the control group and cancer patients without lymphocyte cytotoxins. Serum IgM concentrations were significantly increased in the group of cancer patients (p less than 0.025) and the group with mucin-producing carcinoma (p less than 0.01) with lymphocyte cytotoxins, in comparison to cancer patients and controls without lymphocyte cytotoxins. The lymphocyte cytotoxins were completely or partially adsorbed by red blood cells in 58% of the positive sera. These results suggest that red blood cell cold agglutinins constitute a portion of cytotoxic anti-B lymphocyte antibodies. At present it is unknown whether the lymphocytotoxic antibodies in breast cancer patients are of importance in immunologic host defenses.