Increased levels of interleukin-12 and interleukin-18 in bronchoalveolar lavage fluid of patients with pulmonary sarcoidosis.

We studied prospectively 43 patients with sarcoidosis and 13 normal subjects. IL-12 and IL-18 levels were measured using ELISA kits. Spirometry and body plethysmography were performed using an Elite DL Medgraphics body box. The sarcoidosis group was characterized by significantly higher median range of the plasma angiotensin-converting enzyme (ACE) concentration (72 vs. 34 U/l, P<0.0001), lymphocyte (34 vs. 14%, P<0.0001), CD4+ cells percentages (59 vs. 36%), and CD4/CD8 ratio (4.2 vs. 1.99, P<0.0001). The BALF IL-12 and IL-18 levels were significantly higher in sarcoidosis patients than in healthy subjects (4.1 pg/ml vs. 3.2 pg/ml; P<0.001 and 11.1 pg/ml vs. 6.15 pg/ml, P<0.0001, respectively). A negative correlation between BALF IL-12 and ACE plasma levels (r=-0.33, P<0.05) within the sarcoidosis group was found. Our data suggest a potential role of IL-12 and IL-18 in a local immunologic response in pulmonary sarcoidosis.