Isolation of a tumour-specific antigen from adenocarcinoma of the human breast

Abstract

Patients with malignant neoplasia of the breast were shown to have antibodies in their sera which reacted by tanned-cell hemagglutination against a saline extract of the autochthonous tumour. The presence of antibody which was net adsorbed out by repeated adsorptions with extracts prepared from normal breast tissue suggested that the immune response may be directed against a tumour-specific antigen. The specifie antigen was isolated by the heat dissociation of an immune complex prepared in vitro by mixing antibody and tissue extract. Antigens isolated from breast tissue of 17 patients with infiltrating ductal carcinoma were identical by immunological criteria. Polyacrylamide gel electrophoresis and comparative immunoelectrophoresis confirmed the presence of a tumour-specific antigen in the crude breast tumour extracts. This antigen was not present in saline extracts prepared from normal breast tissue, non-malignant breast tumours, or in saline extracts prepared from other tumours. The molecular weight of the antigen, determined by gel exclusion fractionation was 4.5 x 10? and its amino acid composition indicated a protein rich in acidic amino acids. Immuno-fluorescent antibody studies suggest that the antigen may be a surface antigen.