Role of inflammation in the lung disease of systemic sclerosis: comparison with idiopathic pulmonary fibrosis.

Alveolar inflammation is thought to underlie the development of pulmonary fibrosis in several forms of diffuse lung disease including the connective tissue diseases. The relationship between inflammation and the clinical manifestations of systemic sclerosis (scleroderma), such as skin and lung involvement, is less clear. We therefore evaluated 14 never-smoking patients with systemic sclerosis with pulmonary involvement by bronchoalveolar lavage (BAL) and compared the results with those found in eight nonsmoking patients with idiopathic pulmonary fibrosis (IPF) and eight normal subjects. The patients with scleroderma also underwent gallium citrate Ga 67 scanning. We found that patients with scleroderma and pulmonary involvement have alveolitis that appears to wane with time. In addition, patients with systemic sclerosis have a cellular profile in lavage fluid that appears to differ from that of patients with IPF. Finally, we found a significant correlation between BAL cellular recovery and the single-breath carbon monoxide diffusing capacity in patients with systemic sclerosis but not in patients with IPF. We conclude that inflammation may play an important role in the pathogenesis of the pulmonary disease of scleroderma and that different mechanisms may lead to fibrosis in IPF and scleroderma.