A sandwich enzyme immunoassay of an adenocarcinoma-associated antigen, YH206, in cancer sera.

A sandwich enzyme immunoassay was established to measure an adenocarcinoma-associated antigen (antigen YH206) detected by monoclonal antibody YH206. Levels of antigen YH206 exceeding the cut-off value (25 U/ml) were found in the following percentages of 163 patients with various cancers: stomach cancer 37.2%, colon cancer 14.8%, pancreas cancer 43.3%, common bile duct cancer 28.6%. In contrast, only one out of 33 (3.0%) healthy donors and 7 of 104 (6.7%) patients with benign diseases had slightly elevated levels of the antigen. As regards the relationship between antigen YH206 levels and clinical stages, abnormally high levels of the antigen were found in the following percentages of 29 patients with stomach cancer: stage I 16.7%, II 0%, III 42.9% and IV 54.5%. Serial monitoring of antigen YH206 in two patients with cancer revealed that the level of the antigen increased as the disease progressed. It was also found that perchloric acid treatment of serum might be useful to decrease any false-positive reactions.