Collagen-Specific Antibodies in Patients with Idiopathic Pulmonary Fibrosis

Abstract

Using the enzyme-linked immunosorbent assay (ELISA), we measured IgG antibodies to type I, III and V collagens in sera of 98 patients with idiopathic pulmonary fibrosis (IPF) and 39 normal subjects. Mean levels of types I, III and V collagens-specific antibodies in patients with IPF were significantly higher than those in normal subjects, (p<0.01). Circulating immune complexes (IC) were detected in sera of 26 (35%) out of 74 IPF patients by C₁q solid phase radioimmunoassay. Levels of antibodies to three types of collagens in IC-positive sera were significantly higher than in IC-negative sera (p<0.01 or p<0.05). There were statistically significant correlations among the levels of types I, III and V collagen-specific antibodies (p<0.01). Our data collectively suggest that autoantibodies to collagens, especially to type I collagen, may participate in the pathogenesis of pulmonary fibrosis and may reflect destruction of pulmonary connective tissue.