NORMAL BRONCHIAL EPITHELIAL-CELLS CONSTITUTIVELY PRODUCE THE ANTIINFLAMMATORY CYTOKINE INTERLEUKIN-10, WHICH IS DOWN-REGULATED IN CYSTIC-FIBROSIS

Interleukin-10 (IL-10) is a potent regulatory cytokine that decreases inflammatory responses and T-cell stimulation. We have found that resp iratory epithelial lining fluid (ELF) from patients with cystic fibros is (CF) contains significantly less soluble IL-10 than ELF of healthy control subjects. Although macrophages from the chronically infected l ungs of CF patients appear to be one source of IL-10, little or no int racellular IL-10 was found in bronchoalveolar lavage macrophages from healthy control subjects, suggesting that there must be another source of this cytokine in healthy lungs. We found that bronchial epithelial cells from healthy control subjects constitutively produce IL-10, whi ch appears to be downregulated in CF patients, It is thus likely that the bronchial epithelium plays an important role in regulating the loc al immune response, producing IL-10 to decrease inflammation in the he althy lung. Conversely, downregulation of epithelial IL-10 production in CF airways may contribute to enhancing local inflammation and tissu e damage.