<b>IMMUNOCYTOCHEMICAL LOCALIZATION OF ANGIOTENSIN CONVERTING ENZYME AT THE ULTRASTRUCTURAL LEVEL IN THE HUMAN LUNG AND </b><b>KIDNEY </b>

Abstract

The localization of angiotensin converting enzyme in the human lung and kidney was demonstrated at the ultrastructural level by an immunocytochemical procedure with peroxidase-labelled IgG or Fab' antibody against the enzyme of human kidney. Positive immunocytochemical reaction with the enzyme was observed only on the plasma membrane and micropinocytic vesicles at the luminal site of capillary endothelial cells in the lung. In the kidney, the reaction with the enzyme appeared prominently on the brush border membrane, and to a less extent on the intercellular and basal infolding membrane of the proximal tubules. Parietal and visceral layer cells of Bowman's capsule, especially near the urinary pole, also showed a positive reaction. However, no reaction was observed on the epithelial cells of distal tubules or on the endothelial cells of glomerular and peritubular capillaries.