Occurrence of enzymes of free radical metabolism suggests the possible cytotoxic capacity of the transitional epithelium of the human ureter

Abstract.

Three enzymes, viz., tartrate-resistant acid phosphatase (TRAP), nitric 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 ureters 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 superficial cells of the urothelium. In contrast, SOD showed a patchy or granular distribution within the supranuclear region of these cells. Intra- and subepithelial macrophages exhibited a weak TRAP, but no NOS-I or SOD, immune reaction. On the basis of the immunocytochemical findings, arguments in favor of a cytotoxic function of the superficial cells of the human urothelium are presented.