An animal model of occupational immunologic asthma due to diphenylmethane diisocyanate, with multiple systemic immunologic responses.

Inhalation of MDI in the plastics industry may produce hypersensitivity pneumonitis or immediate-type asthma in workers. A suspension of MDI was given intrabronchially to dogs to determine whether any of the clinical and immunologic human responses could be duplicated, Results showed that dogs produce a systemic immune response to MDI-DSA. Serum MDI-125I-DSA binding was shown by the ammonium sulfate binding technique. Antibody activity of IgG, IgA, and IgM antibody classes was shown by a solid-phase enzyme-linked immunoassay. Precipitating antibodies were detected in he dog serum against MDI-DSA. Immediate-type skin reactivity to MDI-DSA consistent with a canine IgE response occurred. The skin reactivity appeared to correlate with an immediate-type airway response characterized by an increase in pulmonary resistance after intrabronchial MDI. There was transient peripheral blood lymphocyte reactivity to MDI-DSA. The results indicate that a large animal model of human immune response to MDI is available for various immunopathogenic studies.