Comparative studies on monoclonal antibodies raised against human gastric cancer for application to serum diagnosis of cancer.

Four murine MoAbs, KM191(IgM), KM206(IgM), KM230(IgG1) and KM231(IgG1), against human gastric cancer were generated using mice which underwent tolerance treatment to stomach tissues. They exhibited very similar high reactivities to stomach adenocarcinoma cells and low reactivities to normal cells in both membrane binding assay and immunohistochemical analysis. Their antigens were neuraminidase and protease sensitive and existed as macromolecules (1,000Kd) in body fluids. Binding of each antibody was inhibited by the others and KM231 showed the highest binding avidity. When they were used to detect the antigens shed in ascitic fluids and pleural effusions of cancer patients, KM231 allowed the most efficient detection of the antigen. The above results indicated that the four MoAbs bound to closely related epitopes on the same antigen and that the nature of its high binding avidity enabled KM231 to show the greatest efficiency in the detection of the antigen in body fluids. KM231 was applied to serum diagnosis and gave high positive percentages in pancreatic cancer(86%), hepatocarcinoma(87%), gall bladder cancer(50%), and gastric cancer(34%), whereas in healthy persons (0%) and benign diseases except for hepatitis(29%) the percentages were low. KM231 was similar to NS19-9, but quite different from NS19-9 in the high positive percentages of hepatocarcinoma in serum diagnosis.