[Measurement of human serum and liver tissue immunoreactive gamma-glutamyl transpeptidase in patients with various liver diseases].

A solid phase enzyme-linked immunosorbent assay for human immunoreactive gamma-glutamyltranspeptidase(gamma-GTP) was developed. The working range by this assay was from 1 ng to 100 ng. Serum immunoreactive gamma-GTP was significantly elevated in patient with hepatocellular carcinoma and moderate elevation was found in liver cirrhosis. On the other hand, in sera of patients with non neoplastic disease, including acute hepatitis, chronic hepatitis, fatty liver, hemangioma, the immunoreactive gamma-GTP was not significantly elevated. No correlation was found between the serum levels of gamma-GTP determined by enzymatic assay and enzyme-linked immunosorbent assay. In the tissues of hepatocellular carcinoma and metastatic liver tumor, the immunoreactive gamma-GTP contents were also elevated, which were well correlated with the enzyme contents in sera. When immunohistochemical study was carried out, the immunoreactive gamma-GTP was detected diffusely not only in the cell membrane and bile canaliculi but also in the cytoplasm of cancer cell. These results suggest that the hepatoma tissues contain an immunologically active, but enzymatically inactive form of gamma-GTP enzyme.