Host determinants for the development of allergy in apprentices exposed to laboratory animals.

The aim of this study was to evaluate whether determinants of work-related symptoms, skin sensitization and diseases differ between atopic and nonatopic subjects starting a career with exposure to laboratory animals (LA). A cohort of 417 apprentices in animal-health technology was prospectively followed during 32 or 44 months. The effect on the study outcomes of variables derived from questionnaire, skin reactivity, and lung function assessments at baseline were compared in atopic (n=212) and nonatopic (n=183) subjects. Eighty-five incident cases of sensitization to a LA-derived allergen were identified, 67 among atopic and 18 among nonatopic subjects. Baseline rhinitis symptoms in contact with pets and skin sensitization to pets were associated with the development of work-related rhinoconjunctivitis (RC) symptoms in atopic subjects, whereas perannual rhinitis symptoms and having a PC20 (provocative concentration causing a 20% fall in forced expiratory volume in one second) < or = 32 mg x mL(-1) were associated in nonatopic subjects. Baseline rhinitis symptoms on contact with pets and a PC20 value < or = 32 mg x mL(-1) were significant determinants for developing sensitization to a specific allergen in atopic subjects only. Finally, baseline rhinitis symptoms in contact with pets and perannual rhinitis symptoms were associated with the development of occupational RC in atopic subjects, whereas in nonatopic subjects this was associated with having a PC20 value < or = 32 mg x mL(-1). In conclusion, the determinants for the development of specific skin sensitization, symptoms and disease are different between atopic and nonatopic apprentices starting occupational exposure to laboratory-animal-derived allergens.