INTERLEUKIN-8 - DIFFERENTIAL EXPRESSION IN LONE FIBROSING ALVEOLITIS AND SYSTEMIC-SCLEROSIS

Fibrosing alveolitis may occur alone (CFA) or in association with syst emic sclerosis (FASSc). FASSc was recently strewn to have a prognostic advantage over CFA. Because interleukin-8 (IL-8) is likely to be a ma jor determinant of neutrophil alveolitis, we evaluated IL-8 expression in patients with CFA and FASSc and compared it with that in normal in dividuals and sarcoidosis and systemic sclerosis patients without pulm onary involvement (SSc no FA). IL-8 protein in bronchoalveolar lavage fluid (BALF) was assessed by immunoassay, and IL-8 mRNA expression was assessed using Northern analysis and reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridization of lung parenchyma. Compared with normal subjects, IL-8 concentration was significantly g reater in both CFA (p < 0.001) and FASSc groups (p < 0.05) but no diff erent in sarcoidosis. The IL-8 concentration in CFA was higher than in FASSc (p < 0.01) and was related to BAL % neutrophils (r(s) = 0.48, p < 0.01). IL-8 mRNA expression evaluated by Northern analysis was seen only in patients with CFA and FASSc and was related to BAL % neutroph ils (r(s) = 0.63, p < 0.01). We suggest that IL-8 is a key factor in t he pathogenesis of fibrosing alveolitis and that the poorer prognosis of CFA compared with FASSc is related to higher levels of IL-8 within the lower respiratory tract.