Interstitial lung disease in scleroderma. Immune complexes in sera and bronchoalveolar lavage fluid

Interstitial lung disease is a common feature of scleroderma (systemic sclerosis), and it may be a major determinant of morbidity and mortality. Analysis of bronchoalveolar lavage fluid from patients with scleroderma has shown evidence of inflammation in the lower respiratory tract of many patients. We have analyzed sera and bronchoalveolar lavage fluid from scleroderma patients for the presence of immune complexes, which may play a role in the inflammatory process. Using a solid-phase C1q enzyme-linked immunosorbent assay, we detected immune complexes in the sera of 6 of 23 patients (26%) and in none of 32 controls (P less than 0.01). All 6 patients with serum immune complexes had inflammatory cells in bronchoalveolar lavage fluid, and the presence of serum immune complexes correlated with the percentage of neutrophils in lavage fluid (P less than 0.02). Immune complexes were detected in lavage fluid of 11 of 21 patients (52%) compared with 1 of 7 normal controls (14%). Subjects having immune complexes in lavage fluid had a lower forced vital capacity than did those without lavage fluid immune complexes (P less than 0.05). The levels of immune complexes in bronchoalveolar lavage fluid exceeded those in serum by a mean of 45-fold, suggesting either local formation or selective deposition of immune complexes in the lower respiratory tract of some scleroderma patients.