The angiotensine converting enzyme (ACE) is a protein involved in controlling blood pressure. It is located on the inner face of all blood vessels and is particularly concentrated in the blood vessels of the lungs. ACE is also produced by inflammatory cells involved in the body’s defensive mechanisms. ACE levels are useful in the diagnosis and monitoring of sarcoidosis, a disease of unknown origin characterized by the formation of granulomas, small masses of immune and inflammatory cells and fibrous tissue. These granulomas develop under the skin and in several organs. The granuloma outer cells secrete large amounts of ACE. Sarcoidosis is suspected in the presence of a range of symptoms, including the presence of granulomas under the skin, chronic colds and shortness of breath, red and watery eyes and joint pain.
High levels of ACE in the presence of relevant clinical signs and symptoms is compatible with sarcoidosis. ACE is high in 50-80% of people with active sarcoidosis, so a normal enzyme level does not completely eliminate sarcoidosis, particularly the chronic form. A decrease in the enzyme level may indicate spontaneous or treatment-induced remission and allow for a favourable prognosis.