Cytokines in the bronchoalveolar lavage fluid of patients with active pulmonary sarcoidosis.

Numerous cytokines are thought to be important in the pathogenesis of granulomatous inflammation and subsequent fibrosis in sarcoidosis. Interleukin (IL)-6 and IL-8, two recently described cytokines with a broad spectrum of proinflammatory effects, could participate in this disease. We obtained bronchoalveolar lavage fluid (BALF) from 16 subjects (13 African-American, three Caucasian) with untreated active pulmonary sarcoidosis and 10 healthy nonsmoking volunteers (nine Caucasian, one African-American). Concentrated BALF was analyzed by an ELISA for IL-6, IL-8, and albumin. The median IL-6 level was 9.8 pg/mg albumin (range, 0-278) for the sarcoid group compared with 0.14 pg/mg (range, 0.14-9.8) in the control subjects (p = 0.001). The corresponding values for IL-8 were 202 pg/mg (range, 35-2179) versus 5.0 pg/mg (range, 0-44) in the control subjects (p < 0.001). Among the sarcoid patients, BALF IL-6 and IL-8 levels correlated with each other (r = 0.96, p < 0.001), and both cytokines correlated with the BALF neutrophil percentage (r = 0.96 and 0.95, respectively; p < 0.001 for both). No difference was detected in IL-8 concentrations as measured by ELISA in culture supernatants of alveolar macrophages obtained from five sarcoid patients and five control subjects. We conclude that IL-6 and IL-8 are elevated in BALF of patients with active sarcoidosis and may be important modulators of the disease process.