Abstract

Interstitial lung disorders are characterized by chronic inflammation of the lower respiratory tract that include increased numbers of activated alveolar macrophages and fibroblasts. These increased numbers of fibroblasts may be influenced by the alveolar macrophage released factor which was known as alveolar macrophage derived growth factor. To evaluate this hypothesis, alveolar macrophages from bronchoalveolar lavage fluid in rat were incubated with various stimulants including lipopolysaccharide (LPS), free silica dust(Si02), natural carbon dust(NC) for 4 hours and we added these supernatants to the culture of fibroblasts. And we evaluated the fibroblast proliferation, ATP and protein in 1, 2, 3 days. The results were as follows; 1. The number of fibroblasts: in groups of LPS and Si02 show significant increase in comparison with the control group but there was no; difference between NC and control groups. 2. The measurements of ATP in groups of LPS and Si02 tended to be higher than those in the control, and also higher in NC group at the 2nd day than those of control. 3. The amount of protein in LPS and Si02 increased markedly compared with the control group but there was no difference between NC and control groups. 4. In LPS group, we can observe the decrease of ATP and protein after the peak at the 1st day, but;Si02 group show the continuous increase of ATP and protein during the observation period. 5. Increased proportion of ATP and protein indicated their sensitive changes compared with the fibroblast proliferation. These results suggest alveolar macrophages act as the important integrator of the fibrotic process in interstitial lung disorders.