Isolation, characterization and clinical evaluation of the gamma-glutamyltransferase associated with hepatocellular...

Sera from 24 patients with hepatocellular carcinoma (HCC), 30 patients with hepatobiliary diseases other than HCC and 5 normal subjects were analyzed for gamma-glutamyltransferase (GGT) isozymes. In ultracentrifugation, GGT I' was recovered in the non-lipoprotein fraction (the residue), together with GGTs I'', II', I and X. GGTs III to IX were recovered in lipoprotein fractions. GGTs in the lipoprotein fractions were removed beforehand by Affi-Gel Blue chromatography, leaving GGTs I', I'', II', I and X in the non-bound fraction, which was subjected to Con A-Sepharose chromatography. From the double affinity chromatography (DAC), GGTs I' and II' were recovered in the unbound fraction, and GGTs I, I'', II' and X in the bound fraction. GGT activities in the unbound fractions of sera from HCC patients were generally higher than those from patients with other benign hepatobiliary diseases. When the GGT activity of the unbound fractions in DAC was expressed as a percent of the sum of the unbound and bound activities (U/(U + B)) and 22% was set as the lower limit of positive values, 54% of the HCC cases had positive values, while none of the patients with hepatobiliary diseases other than HCC had positive values. The U/(U + B) ratio of GGT in DAC appears to be a clinically useful test for screening HCC.