Hypersensitivity pneumonitis induced by hexamethylene diisocyanate

A case of hypersensitivity pneumonitis (HP) induced by hexamethylene diisocyanate (HDI) is described. Serial determinations of the lymphocyte surface phenotypes by two-color assay revealed the following: 1) increased activated cytotoxic T lymphocytes in the bronchoalveolar lavage fluid (BALF), and 2) increased percentage and absolute number of non-major histocompatibility complex (MHC)-restricted natural killer (NK) cells in the peripheral blood (PB) during the recovery phase of the disease. These findings were considered to be related to the activity of the disease.