Relationship between circulating immune complexes, serum interferon and clinical features in sarcoidosis.

In order to assess the importance of circulating interferons and immune complexes as hypothetical mediators of some immune derangements observed in sarcoidosis, we evaluated serum interferon and immune complex levels in 45 patients with active disease. In none of our patients could circulating interferon be detected, suggesting that an infectious (viral) etiology is very unlikely, and that a great difference exists between sarcoidosis and true autoimmune diseases. On the other hand, circulating immune complexes could be found in 64.4% of our patients. A good correlation could be found with disease stage and duration, but only with 67Ga lung scan among other activity indexes.