In vitro synthesis of angiotensin-converting enzyme by alveolar macrophages is increased in disseminated sarcoidosis

To determine the responsibility of alveolar macrophage (AM) for the increased concentration of angiotensin-converting enzyme (ACE) in bronchoalveolar fluid of patients with sarcoidosis, we cultured AM recovered by bronchoalveolar lavage of 30 subjects: 9 were normal control subjects (group C), 10 had intrathoracic localized sarcoidosis (group LS), and 11 had disseminated intrathoracic and extrathoracic sarcoidosis (group DS). Cells were cultured for 7 days and synthesis of ACE was evaluated according to the difference between final (ACEqe) and initial (ACEqi) ACE content. In groups C, LS, and DS, ACEqi were, respectively, 3.0 ± 1.7, 3.3 ± 1.9, and 4.8 ± 2.4 U/10⁶ AM, and ACEqe were 6.2 ± 1.7, 6.7 ± 2.5, and 11.3 ± 2.8 U/10⁶ AM. ACEqe was higher than ACEqi in all 3 groups (p < 0.01). When cycloheximide was added to the AM culture, ACEqe did not differ from ACEqi, in opposition to what was observed without cycloheximide (p < 0.002). ACEqi in group LS and DS did not differ from ACEqi in Group C, but ACEqe in Group DS was higher than in Groups C and LS (p < 0.01). We conclude that AM both from normal subjects and from subjects with sarcoidosis contain ACE, cultured AM synthesize ACE, and that a greater amount of ACE is produced when AM are obtained from patients with disseminated sarcoidosis.