Immunocytochemical localization of gamma-glutamyltransferase in induced hyperplastic nodules of rat liver.

The immunocytochemical localization of gamma-glutamyltransferase [(5-glutamyl)-peptide:amino-acid 5-glutamyltransferase, EC 2.3.2.2; gamma-GluTase] was demonstrated in hyperplastic liver induced by the carcinogen 2-acetylaminofluorene (2-AAF). The method used a specific antiserum and protein A-horseradish peroxidase and permitted visualization of antigenic sites at both the light and electron microscopic levels. Electron microscopy revealed deposits of 3,3'-diaminobenzidine (DAB) reaction product in the plasma membranes of (i) hyperplastic cells, (ii) bile canaliculi, (iii) endothelial cell membranes, and (iv) lymphocytes. The so-called ATPase activity was localized in the plasma membrane in bile canaliculi and in endothelial cells; the hyperplastic cells show marked variability in the levels of this activity.