Production of monoclonal antibodies to rat lung angiotensin-converting enzyme.

Several monoclonal antibodies to rat lung angiotensin-converting enzyme (ACE) have been produced. The antibodies are of the IgG class, do not inhibit ACE catalytic activity, and do not cross-react with the human or bovine enzyme. They bind in a curvilinear fashion to lung capillary endothelium by immunofluorescence microscopy, and radiolabeled antibody localizes in lung and other organs after intravenous injection into living rats. Each antibody tested appears to bind preferentially to lung rather than kidney ACE by ELISA, a finding supported by weak or absent immunofluorescence of kidney slices in vitro. These antibodies may be used to probe structural differences between ACE in various tissues and, by quantitating changes in accumulation of radiolabeled antibody in experimental models of lung injury, should complement functional measurements in determining the presence of subtle and progressive endothelial damage.