Occurrence and specificity of IgE antibodies to isocyanates in occupationally exposed workers

The levels of IgE antibodies specific for toluene-diisocyanate (TDI), diphenylmethane-diisocyanate (MDI) and hexamethylene-diisocyanate (HDI) were determined in eight workers with an unequivocal history of professional asthma, all having been exposed to isocyanates in the working atmosphere. Five workers were examined at the clinical onset of asthma. They had serum IgE antibodies specific for TDI, MDI and HDI, and depressed pulmonary ventilation parameters. In contrast, three workers, who had only a mild bronchial obstruction at the time of testing, had no anti-isocyanate IgE antibodies. The results indicated that asthma was induced by type I allergic reaction, but other pathogenetic mechanisms of bronchoobstruction could not be completely ruled out.