Humoral and cellular immune responses in asthmatic isocyanate workers: report of two cases.

Two workers (23 and 28 years old) developed rhinitis and bronchial asthma after occupational contact with the isocyanate MDI. Positive skin prick test results for MDI-HSA and IgE antibodies to all isocyanate-HSA conjugates were obtained in both cases, and the inhalation challenge test with MDI produced immediate and late asthmatic reactions. In the patch test and the stimulation assay of peripheral mononuclear blood cells, a specific sensitization to the diamine MDA (in both cases) and to further amines (in one case), as well as to hydrolysates of the respective diisocyanates, was seen, which appears to be independent of the IgE response to isocyanate-HSA conjugates. Our results offer evidence of IgE-mediated, as well as lymphocyte, responses induced by exposures to isocyanate products over several months or years.