Elevation of anti-cytokeratin 19 antibody in sera of the patients with idiopathic pulmonary fibrosis and pulmonary fibrosis associated with collagen vascular disorders

It has been suggested that cytokeratin 19 is expressed in regenerated bronc hoepithelial cells in patients with pulmonary fibrosis, and serum cytokerat in 19 fragment is elevated in patients with pulmonary fibrosis. We hypothes ized that serum antibodies to cytokeratin 19 may be formed in patients with pulmonary fibrosis. To prove the existence of anti-cytokeratin 19 antibodi es in patients' sera, human recombinant cytokeratin 19 was stained with pat ients' sera by a Western immunoblot. Then, we tried to establish an enzyme- linked immunosorbent assay to quantitate anti-cytokeratin 19 antibody in th e sera of patients with idiopathic pulmonary fibrosis (IPF) and pulmonary f ibrosis associated with collagen vascular disorders (PF-CVD). We demonstrat ed the anti-cytokeratin 19 antibody in patient' sera by a Western immunoblo t. In patients with IPF and PF-CVD, significantly high anti-cytokeratin 19 antibody was demonstrated compared with normal volunteers, patients with ch ronic bronchitis, and patients with pneumonia. These results suggest that a nti-cytokeratin 19 antibody may have played a role in the process of lung i njury in pulmonary fibrosis.