Spontaneous production of fibronectin by alveolar macrophages in patients with scleroderma.

Interstitial pulmonary fibrosis is a common manifestation of systemic sclerosis (SSc) and is a pathologic feature shared by a variety of other diseases. In these other disease processes, the glycoprotein fibronectin (FN) has been shown to be released by the alveolar macrophage, and is thus implicated in the development of fibrosis. We therefore studied the release of FN by alveolar macrophages obtained by bronchoalveolar lavage of 17 patients with SSc and 14 controls. We found that SSc alveolar macrophages released significantly more FN than did those of controls. Furthermore, the level of FN correlated positively with the level of inflammation determined by cellular analysis of lavage fluid and negatively with carbon monoxide diffusing capacity. FN may therefore play a role in the development of lung fibrosis in SSc and may be a marker of alveolitis.