OCCURRENCE OF ENZYMES OF FREE-RADICAL METABOLISM SUGGESTS THE POSSIBLE CYTOTOXIC CAPACITY OF THE TRANSITIONAL EPITHELIUM OF THE HUMAN URETER

Three enzymes, viz., tartrate-resistant acid phosphatase (TRAP), nitri c oxide synthase I(NOS-I), and superoxide dismutase (SOD), involved in the production and metabolism of free radicals or radical equivalents , were demonstrated by immunocytochemistry in the urothelium of the ur eters of six patients of various ages. Two of these enzymes (TRAP and NOS-I) were colocalized in the most apical and lateral border of the s uperficial cells of the urothelium. In contrast, SOD showed a patchy o r granular distribution within the supranuclear region of these cells. Intra- and subepithelial macrophages exhibited a weak TRAP, but no NO S-I or SOD, immune reaction. On the basis of the immunocytochemical fi ndings, arguments in favor of a cytotoxic function of the superficial cells of the human urothelium are presented.