Relationship between circulating immune complexes and angiotensin-converting enzyme in pulmonary sarcoidosis.

The relationship between circulating immune complexes (CIC), serum angiotensin-converting enzyme (SACE) and clinical features was investigated in 119 patients with sarcoidosis. CIC, measured by the C1q-binding test and a polyethylene glycol precipitation test, were detected in 42% of the patients. A significantly higher level of CIC was found in patients with duration of the disease of more than 2 years and in patients in stage II or III on chest X-ray. SACE was increased in 45% of the patients, most frequently in those with active disease and in those in stage II or III on chest X-ray. No positive correlation was found between CIC and elevated levels of SACE.