Angiotensin converting enzyme in sarcoidosis and in silicosis

Angiotensin converting enzyme (ACE) activities of bronchoalveolar lavage fluid (BALF) and serum in patients with sarcoidosis and with silicosis were measured. Serum ACE was measured by enzymic assay and radioimmunoassay. There was a close relationship between ACE activity and content (r = 0.78). Serum ACE activities in patients with active sarcoidosis (37.5 +/- 11.1 nmol/min/ml, mean +/- SD) and with silicosis (25.5 +/- 9.3) were significantly elevated from the control (18.6 +/- 6.0). BALF ACE activities in the control, patients with active sarcoidosis and with silicosis were 0.23 +/- 0.19 nmol/min/ml, 0.94 +/- 0.97 and 0.38 +/- 0.05, respectively. BALF ACE in patients with active sarcoidosis and with silicosis were significantly different from the control. When BALF ACE was corrected by the cell count of alveolar macrophage (per 10(6) cells), activity was significantly different from control only in the patients with sarcoidosis. Moreover, only the alveolar macrophages in sarcoidosis were stained by immunofluorescence and immunocytochemistry using rabbit antihuman ACE antibody. Induction of ACE in alveolar macrophage might have an important role for the activity or progression of sarcoidosis.