Antibodies to collagen in scleroderma.

Using the enzyme-linked immunosorbent assay (ELISA), we detected antibodies to interstitial (type I) and basement membrane (type IV) collagens in the sera of patients with scleroderma (systemic sclerosis). Antibodies against type IV collagen were found in significant levels in these patients and correlated with the presence of abnormal pulmonary diffusion capacity. Levels of antibodies to type I collagens also correlated significantly with pulmonary diffusion capacity. Absorption of sera with type I or type IV collagens before analysis in the ELISA eliminated reactivity in an antigen-specific pattern, indicating that these antibodies reacted with determinants specific for either type I or type IV collagens. The removal of immune complexes by ultracentrifugation had no effect on serum antibody levels. Autoantibodies to basement membrane and interstitial collagens may participate in the pathogenesis of scleroderma.