Development of radioimmunoassay for gamma-glutamyl transferase using pancreatic enzyme

A radioimmunoassay (RIA) for the determination of gamma-glutamyl transferase (GGT) was developed using human pancreatic enzyme as antigen. The assay allows the determination of GGT in concentrations as low as 80 ng/ml, and it is reproducible and specific. A good parallel relation was demonstrated between the standard curve and dilution curves for serum, urine, bile, and partially purified kidney GGT. In normal individuals, the mean serum concentration of GGT determined by RIA was found to be 3.43 micrograms/ml (SD +/- 1.20). Enzyme activity calculated from the GGT concentration measured by the radioimmunoassay using a regression equation was approximately twice as great as that determined by conventional enzyme assay.