Clinical and immunologic findings of methylene diphenyl diisocyanate-induced occupational asthma in a car upholstery factory

Authors


Correspondence:
Hae-Sim Park, Department of Allergy and Rheumatology, Ajou University School of Medicine, San-5, Wonchun-dong, Youngtong-gu, Suwon, 443-721, Korea. E-mail: hspark@ajou.ac.kr

Summary

Background Although methylene diphenyl diisocyanate (MDI) is widely used in many industries, there have been few immunological studies of MDI-induced occupational asthma.

Objectives We investigated the effects of MDI exposure on the clinical and immunologic condition of workers in a single car upholstery factory.

Methods Fifty-eight MDI-exposed workers were studied. Work-related lower-respiratory symptoms (WRRS) were identified using a questionnaire. Serum-specific IgE and IgG antibodies to MDI-human serum albumin conjugate were detected by ELISA. Atopy was evaluated using a skin prick test. MDI-induced occupational asthma was confirmed in the symptomatic workers with a positive result on an MDI-specific inhalation test.

Results Thirteen (22.4%) of the subjects complained of WRRS. MDI-induced occupational asthma was confirmed in five (8.6%) of the workers, and occupational eosinophilic bronchitis was confirmed in two (3.5%). The prevalence of specific IgG antibodies (20.7%) was higher than that of specific IgE antibodies (8.6%). The prevalence of MDI-induced occupational asthma/eosinophilic bronchitis was strongly associated with the presence of both WRRS and serum-specific IgG antibodies to an MDI-human serum albumin conjugate (P<0.01, <0.05, respectively).

Conclusion These findings suggest that MDI could be a causative agent of occupational asthma among MDI-exposed workers. The prevalence of MDI-induced occupational asthma was 8.6%, and MDI-induced eosinophilic bronchitis was confirmed in two workers. The presence of work-related lower-respiratory symptoms and serum-specific IgG antibodies to an MDI-human serum albumin conjugate may be used to predict MDI-induced occupational asthma/eosinophilic bronchitis in MDI-exposed workers.

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