The pathogenesis of interstitial pneumonia and the role of cytokines

Various cytokines are known to participate in the pathogenesis of interstitial pneumonia follewed by lung fibrosis due to the proliferation of fibroblasts and production of collagen fibers. Patients with interstitial pneumonia including idiopathic interstitial pneumonia (IIP) and interstitial pneumonia with collagen vascular disease (IP with CVD) were examined by bronchoalveolar lavage (BAL). Cytokines such as IL-1α, TGF-α, and TGF-β in BAL fluid were measured by enzyme linked immunosorbent assay (ELISA). The concentrations of TGF-α and TGF-β in BAL fluid of patients with IIP and IP with CVD were higher than those of normal control, while IL-1α, in BAL fluid was detected in few patoents. The level of TGF-β in BAL fluid was higher in patients with greater decreases in pulmonary function and overt fibrosis on chest X-ray film, although TGF-α was higher in patients with milder disorders. The concentrations of TGF-α and TGF-β showed positive correlation with soluble IL-2 receptor as well as procollagen type Ⅲ in BAL fluid. These results indicated that cytokines regulationg lung fibrosis play important roles in the pathogenesis of interstitial pneumonia