Bronchoalveolar lavage in amiodarone pneumonitis. Cellular abnormalities and their relevance to pathogenesis.

To investigate the contribution of direct cytotoxicity and immune-mediated hypersensitivity to the pathogenesis of amiodarone pneumonitis, we evaluated cells recovered by bronchoalveolar lavage from 13 patients with amiodarone pneumonitis. Alveolar macrophages from all patients contained two types of abnormal inclusions: small clear vacuoles and large phagolysosomes containing phospholipid in lamellar structures, abnormalities previously attributed to direct cytotoxicity from amiodarone. However, these changes were always associated with abnormalities in the numbers and types of immune and inflammatory cells present in the lower respiratory tract, which closely resemble those seen in hypersensitivity pneumonitis associated with inhaled antigens. Following discontinuation of amiodarone and institution of corticosteroid therapy, clinical improvement correlated with a return toward normal in the pattern of inflammatory cells present in the lung, although alveolar macrophages continued to display evidence of drug-induced cytotoxicity. These findings support the possibility that a cell-mediated immune response usually plays a role in the pathogenesis of amiodarone pneumonitis, although direct cytotoxicity may predispose these patients to the development of this abnormal immune response.