Progressive inflammation and fibrosis are the central processes in the pathogenesis of pulmonary fibrosis. It is believed that macrophages in areas of chronically inflamed lung play a key role in fibrotic response. Therefore

we investigated the effects of alveolar macrophage （AmΦ） conditioned media from interstitial lung disease （ILD） patients on lung fibroblast proliferation and procollagen mRNA expression. After stimulating with AmΦ conditioned media from ILD patients

the fibroblast proliferation increased 71. 4 % compared with the control

but for media from bronchial carcinoma （BC） patients

it just increased 14. 3%. There is a significant difference between the two groups （P<0. 05）. The procollagen a1 （Ⅰ） mRNA in fibroblasts stimulated with AmΦ conditioned media from ILD patients was increased 21. 3 %

and a1 （ Ⅲ） was 37. 2% higher than control （P<0.05）. It increased 6. 8% and 12. 8% for media from BC patients respectively

but there was no difference when compared to the control. We considered that AmΦ from ILD patients might be in an activated state and could release some growth factors to stimulate fibroblast proliferation and promote collagen DNA expression.