Markers of inflammation and bronchial reactivity in children with asthma, exposed to animal dander in school dust

Several studies have confirmed the presence of animal dander allergens in s chool dust but the effect of this indirect animal exposure on health has no t been evaluated. In this study we investigated bronchial reactivity and ma rkers of eosinophil activity and inflammation during two separate weeks of school in 10 children with mild asthma and a positive skin prick test to ca t and dog. At the beginning and the end of the first week the children unde rwent bronchial challenges with methacholine, and at the beginning and the end of the second week they underwent nasal lavages (NAL) and induced sputu m samplings. Blood and urine samples for analysis of inflammatory markers w ere obtained before and after both school weeks. Peak expiratory flow (PEF) and symptoms of asthma and allergy were recorded daily, and spirometry was performed on each visit. The exposure to animal dander allergens was estim ated from dust samples obtained in the subjects' schools and homes. Bronchi al sensitivity to methacholine increased in the week when this was measured . The proportion of eosinophils in peripheral blood, and urinary eosinophil protein X (EPX), decreased in both weeks. There was a trend towards an inc rease of eosinophil peroxidase (EPO) and myeloperoxidase (MPO) in sputum in the week when these proteins were measured. The concentrations of cat (Fel dl) and dog (Can fl) allergens were higher in dust collected in schools th an in homes. Our results show that in children with mild asthma and animal dander allergy, there is a significantly increased bronchial sensitivity to methacholine after one school week. There is also a significant decrease i n the number of circulating eosinophils and a trend towards an increase of sputum EPO, which could correlate with the early phase of eosinophil recrui tment to the lungs. These effects may be related to the continuous exposure to animal allergens in school dust.