Histochemistry of gamma-glutamyl transpeptidase in human liver biopsies

The histochemical activity of gamma-glutamyl transpeptidase is examined in human liver biopsy specimens in normal and pathological conditions. Different histochemical patterns can be recognized. In histologically normal liver a faint sinusoidal membrane staining is observed. In pathological liver tissue invariably a pronounced canalicular gamma-GT activity is detected in addition to the faint sinusoidal membrane activity. The canalicular staining pattern is variable in extent and staining intensity, without clear correlation with specific disease entities. Cases with severe degrees of cholestasis, however, show a "washed-out" appearance of the tissue, apparently parallel to the degree of cholestasis. This phenomenon may be explained by the detergent action of bile salts accumulating in cholestatic tissue.