The immunocytochemical detection of angiotensin-converting enzyme in alveolar macrophages from patients with sarcoidosis

Angiotensin-converting enzyme (ACE) was detected in alveolar macrophages obtained by bronchoalveolar lavage (BAL), but not in lymphocytes and other cells, by immunofluorescence using anti-human ACE antibody. The enzyme was localized on the surface of plasma membrane and cytoplasmic processes of alveolar macrophages, as demonstrated by immunoelectron microscopy. The immunocytochemical staining for ACE in alveolar macrophages from patients with sarcoidosis was intense, which was consistent with the result that ACE activity in BAL cells from patients with sarcoidosis was significantly higher than in cells from normal subjects and from patients with nonsarcoid lung diseases. Part of this work was presented at the 8th Asia-Pacific Congress on Diseases of the Chest, Tokyo, July 11–15, 1983