Angiotensin-converting enzyme activity in serum and bronchoalveolar lavage fluid after damage to the alveolo-capillary barrier in the human lung

OBJECTIVE: Angiotensin-converting enzyme (ACE) is considered as a possible marker for endothelial cell damage in serum or bronchoalveolar lavage fluid. This hypothesis was tested during cardiac surgery and during the adult respiratory distress syndrome. DESIGN: We used patients with an expected different degree of endothelial cell damage. ACE levels in serum and bronchoalveolar lavage fluid were compared with indirect markers of alveolo-capillary barrier integrity. SETTING: Interdisciplinary team in a university hospital. METHODS: 13 Cardiac surgery patients received no glucocorticoids and 13 others received 2g methylprednisolone before extracorporeal circulation. Thirteen patients were used as controls and 15 patients had nonseptic adult respiratory distress syndrome. All underwent bronchoalveolar lavage for ACE determination. RESULTS: At different times during surgery serum angiotensin-converting enzyme levels were not significantly different between the two groups. In post-operative bronchoalveolar lavage fluid, angiotensin-converting enzyme levels were significantly higher in patients who received corticoids (27.8±1.7U/1, mean±SEM), compared to patients without corticoids (19.8±1.4U/1), control patients (18.2±1.3U/1) or patients with full blown non-septic adult respiratory distress syndrome (18.8±1.1U/1). There were no correlations between lavage angiotensin-converting enzyme and other parameters for alveolo-capillary membrane integrity in the lavage fluid such as the number of neutrophil cells, albumin or protein concentration, and between lavage angiotensin-converting enzyme and PaO(2)/FIO(2) ratio during lavage. CONCLUSION: Angiotensin-converting enzyme activity in serum or bronchoalveolar lavage fluid does not reflect damage of endothelial cells or damage of alveolocapillary integrity in acute pulmonary disease.