Abstract
The existence of CMI to tumor‐associated antigens present in 3 M KCl extracts of breast carcinomas was demonstrated in a group of breast cancer patients by the leukocyte migration inhibition (LMI) assay. When crude KCl extracts were tested, 3 of 5 breast cancer patients gave a positive response to autologous tumor extracts. Eleven of 20 gave a positive response to allogeneic extracts as compared to 3 of 22 controls (including 6 patients with benign breast disease, 7 with non‐mammary cancers and 9 normal controls). Extracts of fibrocystic disease tissue gave positive LMI tests in 2 of 5 breast cancer patients, suggesting the presence of antigenic cross‐reactivity between benign and malignant breast disease. An extract of a medullary carcinoma of breast was fractionated on Sephadex G‐200 and the effluent pooled into three fractions. The high molecular weight fraction produced LMI in 11 of 22 breast cancer patients and in 1 of 19 controls, including patients with benign breast disease, other cancers and normal individuals. The low molecular weight fraction produced LMI in both the benign (4 of 6) and the malignant breast disease (6 of 20) patients, but not in the controls (0 of 12). A simple fractionation technique has thus separated “cancer‐specific” from “organspecific” activity. Sephadex G‐200 fractions were active at a much lower protein concentration than the crude 3 M KCl extracts.