Clinical significance of appearance of serum gamma-glutamyl transpeptidase isozyme.

Serum gamma-glutamyl transpeptidase zymograms were examined by 4--26% polyacrylamide gradient gel slab electrophoresis using sera from 90 patients with various hepatobiliary diseases. The isozyme bands were separated into 13 bands in order from post albumin fraction. Characteristic patterns of the zymograms were obtained in cases of hepatocellular carcinoma and cholestasis. Bands I, II and II' may be specifically related to hepatocellular carcinoma. Band I was observed frequently in hepatocellular carcinoma, however it was also occasionally observed in alcoholic liver injury and metastatic liver cancer. Both band II and II' were only observed in hepatocellular carcinoma cases. The origin of band II and/or II' was not clarified but band I might appear through some proteolytic process in hepatoma tissue and also liver affected by alcohol. In cholestatic cases the activity of bands III and IX were prominent. The frequency of band VI decreased according to the severity of jaundice and a negative correlation appeared to exist between bands III and VI. This phenomenon may be partially related to lipid metabolism disorder which is frequently observed in cholestasis. Results of analysis of the frequency of appearance of these bands did not permit differentiation between intra- and extrahepatic cholestasis.