Amiodarone-induced hypersensitivity pneumonitis. Evidence of an immunological cell-mediated mechanism.

Interstitial pneumonitis developed in a patient who had received a cumulative dose of 985 g of amiodarone in nine years. No other cause for pneumonitis was found. The following findings favor an immunologic mechanism of hypersensitivity due to amiodarone: positive skin and basophil degranulation tests with amiodarone; lymphocytosis and inverted ratio of helper/suppressor T lymphocytes in bronchoalveolar lavage fluid; secretion of leukocyte inhibitory factor, as shown by the inhibition of migration of peripheral blood leukocytes; and positive lymphoblastic transformation in the presence of amiodarone.