The localization of thromboxane synthase in normal and pathological human kidney tissue using a monoclonal antibody...

Thromboxane, excreted in the urine in increased amounts in glomerular, vascular and tubulo-interstitial diseases, is considered to originate from the kidney. The localization of thromboxane synthase, a key enzyme of arachidonic acid metabolism, was studied in the human kidney by immunohistology using the monoclonal antibody Tü 300. In the interstitial tissue dendritic reticulum cells surrounding the tubules expressed high concentrations of the enzyme. In glomeruli the enzyme was weakly expressed in podocytes. This was confirmed by co-localization with an antiserum directed to podocalyxin, a marker of the visceral epithelial cells. In the study of various kidney diseases, massive accumulation of thromboxane synthase containing cells was observed in interstitial diseases, whereas in glomerular diseases there were no differences from normal kidney; in a case of thrombotic microangiopathy podocytes exhibited an increase in thromboxane-synthase. The thromboxane-synthase positive infiltrating interstitial cells were shown by conventional light microscopy to be mononuclear phagocytic cells. The physiological sources of renal thromboxane are dendritic reticular cells and podocytes. In interstitial renal disease infiltrating cells of the monocyte/macrophage system constitute the major site of thromboxane synthesis. In glomerular disease, a characteristic alteration of thromboxane-synthase was not found.