Lung inflammation in sarcoidosis: comparison of serum angiotensin-converting enzyme levels with bronchoalveolar lavage and gallium-67 scanning assessment of the T lymphocyte alveolitis.
Serum angiotensin-converting enzyme (ACE) is elevated in many patients with pulmonary sarcoidosis and has been proposed as a measure of disease activity. The present study was designed to evaluate the possible relationship between serum ACE and direct measures of the intensity of the alveolitis of pulmonary sarcoidosis as measured by bronchoalveolar lavage and gallium-67 (67Ga) scans. To accomplish this, 64 measurements of serum ACE, lavage T lymphocytes, and lung uptake of 67Ga were performed in 41 patients with biopsy-proven sarcoidosis. Elevations of serum ACE were found on at least one occasion in 17 patients (41%). However, serum ACE was found to be a poor predictor of the intensity of alveolitis in sarcoidosis as assessed by the quantitation of bronchoalveolar lavage cells that were T lymphocytes and by 67Ga scanning. Elevated serum ACE did not predict which patients would have elevated proportions of lavage T lymphocytes, which patients would demonstrate increased pulmonary uptake of 67Ga, or which patients would have high-intensity alveolitis as defined by a combination of these criteria. These observations suggest that while serum ACE may be useful in diagnosing sarcoidosis, it does not reflect accurately the intensity of the alveolitis of the pulmonary component of this disease.