Elevated Interleukin-8 in the Bronchoalveolar Lavage Fluid of Patients with Idiopathic Pulmonary Fibrosis

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Idiopathic pulmonary fibrosis (IPF) is a disease of unknown etiology and activated alveolar macrophages and neutrophils play important roles in its pathogenesis. Interleukin-8 (IL-8) is thought to be released by activated mononuclear phagocytes and exhibits potent chemotactic activity for neutrophils. We examined the levels of IL-8 in bronchoalveolar lavage fluid (BALF) from the patients with IPF (n=12) and control subjects (n=5). The level of IL-8 in patients with IPF was 59.4±51.2pg/ml BALF which was significantly higher than that in the controls (3.02±0.99pg/ml BALF; p<0.05). A close correlation was found between the level of IL-8 and BALF neutrophil content, whether expressed as a percentage (r=0.86; p<0.01) or cells per milliliter BALF (r=0.62; p<0.05). The level of IL-8 showed a positive correlation with alveolar-arterial oxygen difference (A-aDO_2), (r=0.586; p<0.05) and negative correlation with PaO_2 (r=0.753; p<0.01). These findings suggest that IL-8 plays an important role in the pathogenesis of IPF and that IL-8 content in BALF may be a useful parameter of its severity.