Prevalence of work-related symptoms and serum-specific antibodies to wheat flour in exposed workers in the bakery industry

Background: Although baker's asthma (BA) is a common occupational asthma, there have been few reports on this disease in Korean subjects. Objectives: We evaluated the prevalence of serum-specific IgE, IgG1, and IgG4 antibodies in relation to work-related respiratory symptoms in a single industrial bakery. Methods: Three hundred and ninety-two bakery workers were administered and taken a questionnaire regarding respiratory symptoms. For symptomatic workers, the methacholine bronchial challenge test and specific bronchoprovocation tests with wheat extracts were carried out. Skin prick tests were performed and serum-specific IgE, IgG1, and IgG4 antibodies to wheat flour were detected. The IgE- and IgG4-binding components were identified by immunoblotting. Results: Sixty-seven workers (17.1%) complained of work-related upper and lower respiratory symptoms. The prevalence of BA based on positive bronchoprovocation test results was 1.5%. The sensitization rate to wheat flour was 5.9% by skin prick test and 6.5% by ELISA, and was closely associated with the presence of atopy and work-related lower respiratory symptoms (P<0.001 for both). IgE immunoblotting revealed six major IgE-binding components (27, 31, 36, 43, 54, and 72 kDa). The presence of wheat-specific IgG1 and IgG4 antibodies was found to be significantly associated with exposure intensity (P<0.05 for both). Conclusions: The overall prevalence of wheat sensitization in a Korean bakery was 5.9%. We confirmed that an IgE-mediated response is the major pathogenic mechanism for the induction of work-related symptoms in wheat-exposed workers. Wheat-specific IgG antibodies may represent current or previous exposure to wheat dust.