Amiodarone-associated pulmonary fibrosis. Evidence of an immunologically mediated mechanism.

A case of pulmonary fibrosis attributed to amiodarone was studied immunologically and morphologically. A specific antibody of the IgG class was identified in the serum of this patient which reacted with the patient's own lung tissue. The immunoglobulin did not react with normal lung tissue nor was there evidence of reaction with lung tissue from patients with pulmonary fibrosis but without a history of amiodarone therapy. The patient probably developed a humoral antibody response to a lung-amiodarone complex with the amiodarone acting as a hapten which bound in vivo to the lung tissue. The subsequent antibody-antigen reaction stimulated a proliferation of pulmonary fibroblasts and probably enhanced the fibro-collagen deposition in the lung.