Specific bronchoalveolar lavage IgG antibody in hypersensitivity pneumonitis from diphenylmethane diisocyanate

We evaluated a patient for dyspnea, fever, malaise, and hypoxemia that developed after exposure to diphenylmethane diisocyanate (MDI). Specific inhalation challenge with MDI caused fever, leukocytosis, a restrictive decline in forced vital capacity, and a decrease in Pao2 several hours after challenge. Bronchoalveolar lavage 24 h after challenge showed lymphocytic alveolitis. Specific IgG antibodies to MDI human serum albumin (MDI-HSA) conjugate were demonstrated in serum and bronchial lavage fluid using the enzyme-linked immunoabsorbent (ELISA) technique. These findings suggest participation of both humoral and cellular immunity in the pathogenesis of hypersensitivity pneumonitis from isocyanate exposure.