Immunological studies in breast cancer. Modifying activity of the serum (MSA)

Cancer patients' sera can modify results obtained with cell mediated immune reactions in vitro. We have investigated the modifying activity of breast cancer patients' sera on the inhibition elicited in a leukocyte migration inhibition test with two cellular extracts of breast cancer hepatic metastases (CaMa Hu-2 and CaMa Hu-3). These extracts elicited positive delayed hypersensitivity reactions in vivo in 80% of the patients studied with at least one of the two preparations, and 40% of the patients showed positive results with both preparations. In vitro similar quantitative results were obtained with the leukocyte migration inhibition test. With these antigenic extracts significant statistical differences were obtained between the cancer group compared to the controls with benign breast lesions (p < 0.01) and to the normal controls (p < 0.001). The modifying activity of the sera (MSA) showed three effects: blocking , potentiation and induction of inhibition of leukocyte migration in vitro in 80% of samples of sera tested. Blocking activity was associated mainly with not too advanced clinical stages, while potentiation and induction effects were associated with more advanced clinical stages. These MSA may be explained by assumed presence of tumor antigenic material, antibodies and immune complexes in breast cancer patients' sera.