Angiotensin-converting enzyme in macrophages and Freund's adjuvant granuloma.

Low angiotensin-converting enzyme (ACE) activity was found in rat and mouse peritoneal macrophages, in rat and rabbit pulmonary alveolar macrophages, in cultured mouse peritoneal macrophages stimulated i.p. for four days by thioglycollate, and in rabbit pulmonary alveolar macrophages stimulated in culture by 0.1 to 100 microgram/ml Salmonella typhosa endotoxin for four days. Rat subcutaneous Freund's adjuvant granulomas induced with Mycobacterium butyricum or M. tuberculosis H37 Ra contianed low ACE activity which was generally lower than that present in control tissues. Increased ACE activity in sarcoidosis and Gaucher's disease lesions does not reflect a universally high synthesis of ACE in mammalian macrophages or granulomas, but may be due to specific mechanisms.