[Studies on pulmonary fibrosis induced by interstitial macrophages].

OBJECTIVE

To evaluate the role of interstitial macrophages (IMs) in modulating the proliferative capacity of fibroblast(FB).

METHOD

IMs isolated by collagenase IA digestion of disaggreted lung tissues from bleomycin-treated rats were studied in this regard. The culture supernatants of alveolar macrophages(AMs) and of IMs were added to culture media of FBs.

RESULT

The releases of growth factors by the two sub-populations of macrophage were already elevated on 1st day following bleomycin instillation, and peaked on 7th day at a level nearly 3-fold above that of control groups(IM 342%, AM 332%, P < 0.01), the proliferative capacity was correlated well with the levels of TNF alpha and PDGF (r = 0.657, 0.713, P < 0.01).

CONCLUSION

Not only AMs, but also IMs could release growth factors to modulate the proliferation of FBs in vitro. IMs might be of more significance in maintenance of the process of pulmonary fibrosis because of its proximity to FBs.