REACTIVE OXYGEN SPECIES AND NEUTROPHIL RESPIRATORY BURST CYTOCHROME B558 ARE PRODUCED BY KIDNEY GLOMERULAR CELLS IN PASSIVE HEYMANN NEPHRITIS

Reactive oxygen species (ROS) have been implicated in the production o f glomerular damage in passive Heymann nephritis (PHN), an experimenta l form of membranous nephropathy with neutrophil-independent proteinur ia. immunohistochemistry with monoclonal antibodies specific for cytoc hrome b558 (a major component of the oxidoreductase complex of the res piratory burst in stimulated neutrophilic granulocytes) showed that th is enzyme is localized within visceral glomerular epithelial cells (GE Cs) in a dense, granular pattern in rats with PHN and proteinuria. By immunoelectron-microscopy, the cytochrome was found in membrane vesicl es within the GEC and also extracellularly on the GEC membranes facing the glomerular basement membrane (GBM). By immunoblotting, cytochrome b558 was detected in highest concentration in lysates of isolated glo meruli from proteinuric rats. By contrast, only traces were found in n ormal glomeruli by immunohistochemistry. Depletion of complement aboli shed the expression of the cytochrome. Using an ultrastructural cerium -H2O2 histochemistry technique, the functional activity of the glomeru lar ROS-generating system was demonstrated exclusively in proteinuric PHN, where H2O2 Was found in highest concentration within the GBM. The se results provide evidence that in rats with PHN and proteinuria, the GECs express and externalize respiratory-burst enzymes that generate ROS in a manner similar to neutrophilic granulocytes, which could then lead to glomerular damage.