Role of superoxide dismutase in the pathogenesis of pyelonephritis: immunological localization of superoxide dismutase in human renal tissues.

The enzyme superoxide dismutase affords a protective effect from renal scarring secondary to acute pyelonephritis in primates. To investigate the relationship between renal superoxide dismutase content and age we selected formalin-fixed normal human renal tissue from subjects of varying age, ranging from premature infant to adult, for immunostaining with human anti-superoxide dismutase antibody using the peroxidase-antiperoxidase technique. Sections that demonstrated acute pyelonephritis were immunostained for comparison. Immunostaining for superoxide dismutase was detected consistently in the proximal tubular cell cytoplasm in all specimens regardless of subject age. Superoxide dismutase was not detected in other segments of the nephron. In kidneys that demonstrated acute pyelonephritis we detected enhanced immunostaining in the proximal tubules, as well as increased background staining related to the inflammatory cells present. These results in conjunction with recent demonstrations of proximal tubular cell endocytosis of bacteria suggest that superoxide dismutase has an important role in mediating the initial events of pyelonephritis within the proximal tubular cell.