Carcinoembryonic antigen producing cultured cell lines enable detection of autoantibodies in sera from patients with gastrointestinal cancer.

Of 16 human malignant tumor cell lines established in our laboratory, seven lines, including three gastric cancer cell lines derived from patients with cancer, were found to carry carcinoembryonic antigen on their cell surface, as determined by radioimmunoassay and indirect immunofluorescence. The existence of antibodies (IgG class) against the gastric cancer cell lines (HPE-GAC-T, -2, -3) and lung cancer cell line (HPL-Ad-K) in the sera of patients with gastrointestinal cancer (incidence 70.8%) was demonstrated by indirect immunofluorescence. In nonmalignant cases and healthy controls, the incidence was 7.7 and 3.2%, respectively. Specificity of the antibodies detected in the sera of patients with gastric cancer was examined by absorption and blocking test methods of immunofluorescence. Even though there was an apparent heterogeneity of the specificity among the antibodies, the detection of such antibodies may be a feasible and practical approach to a clinical diagnosis of malignancy.