Immunohistochemical detection of gamma-glutamyl transpeptidase in normal human tissue.

We developed a new, highly specific antibody that localizes gamma-glutamyl transpeptidase (GGT) in formalin-fixed sections of human tissue. The specificity of the antibody, GGT129, is demonstrated by immunostained Western blots of whole cell homogenate from five different tissues. The utility of the antibody is shown by a comprehensive study of GGT expression in normal human tissue. This study reveals GGT expression for the first time in a number of tissues, including glands in the endocervix, endometrium, and adrenals. Strong immunoreactivity was observed on the surface of renal proximal tubule cells, hepatic bile canaliculi, and capillary endothelial cells within the nervous system. Secretory or absorptive cells in sweat glands, prostate, salivary gland ducts, bile ducts, pancreatic acini, intestinal crypts, and testicular tubules were also GGT-positive. Small bands of positively stained stromal cells and GGT-positive histiocytes were seen in some tissues. Analysis of human fetal tissue shows that the developmental expression of GGT differs in humans and rodents. These findings form the basis for further work on GGT induction in tumors and the effect of GGT expression on the response of tumors to chemotherapy.