Metabolism and subcellular localization of angiotensin converting enzyme in cultured human monocytes

The enhancement of monocyte ACE activity during culture by autologous T-lymphocytes was shown to be due to a stimulation of the rate of ACE synthesis. The rate of synthesis increased from 0.020 mU/10(6) monocytes/hr in monocytes cultured alone to 0.063 mU/10(6) monocytes/hr in monocytes co-cultured with T-lymphocytes. The presence of T-lymphocytes during culture did not alter the rate of ACE degradation observed in monocytes cultured alone. The ACE induced in monocytes by T-lymphocytes appears to be an ecto-enzyme. Brief exposure to diazosulfanilic acid (10(-3) M) and papain (250 micrograms/ml) reduced ACE activity 89% and 66%, respectively, without appreciably altering the activity of the cytosolic enzyme, lactate dehydrogenase.