Occupational respiratory allergy to lettuce in lettuce farmers.

BACKGROUND Lettuce-associated respiratory allergy has never been reported before. The aim of this study was to clarify the clinical condition of lettuce-associated respiratory allergy and to identify the lettuce antigen which induces allergic symptoms. METHODS We distributed questionnaires to 1,168 lettuce farmers and performed medical examinations in those who exhibited respiratory symptoms related to occupational exposure to lettuce. We analyzed specific IgE-binding proteins in the sera of patients through immunoblotting analysis and determined molecular characterization of the IgE-binding bands using liquid chromatography-mass spectrometry. RESULTS A total of 932 farmers(80%) responded to the questionnaire. Of those, 7% exhibited lettuce-associated respiratory symptoms, during harvesting and packaging. Thirteen patients were diagnosed with allergy to lettuce and agreed to undergo further examinations. The percentage of activated basophils in these patients was significantly higher compared with that reported in negative controls (P 50% of patients were identified as epidermis-specific secreted glycoprotein EP1-like (51 kDa). CONCLUSION The present analysis identified a novel lettuce allergen. This allergen may have clinically useful applications, such as specific IgE testing and allergen specific immunotherapy.