Resuspension of indoor aeroallergens and relationship to lung inflammation in asthmatic children

Abstract

Studies have shown links between the concentration of allergens found in homes and asthma. Inhalation of allergens present in settled residential dust can occur when the dust is resuspended via human activity or air currents. Although previous studies have measured allergen concentrations in homes, the focus has been on the presence of the allergens in settled dust samples. However, the actual inhalation exposure is to airborne allergens. The relationship between the settled dust composition and suspended allergens and endotoxin and the effect of exposure of these aeroallergens to asthmatics are not well understood for species typically present indoors. In this study, settled dust and airborne particulate matter samples were collected in the homes and school classrooms of asthmatic children of ages 9 to 16 and analyzed for endotoxin and allergens including dust mite and cockroach allergen, and dog and cat dander (Der p1, Der f1, Bla g1, Can f1, and Fel d1, respectively). Concentrations of cockroach allergen were below detection limit for all samples. Measurements of the settled dust samples show higher dust mite allergen in bedroom samples than in living room samples. Concentrations of airborne endotoxin and indoor allergens were generally higher in the homes than those measured at school. Within the homes, higher concentrations of airborne allergens and endotoxin were observed in the living rooms compared to the bedrooms. Resuspension rates for endotoxin, dust mite allergen, and, cat and dog dander were estimated in this study. Calculated resuspension rates for cat dander (8.1x10(-7)+/-3.5x10(-7)min(-1)) and dust mite allergen (2.1x10(-6)+/-7.6x10(-7)min(-1)and 1.4x10(-5)+/-4.6x10(-6)min(-1) for Der p 1 and Der f 1, respectively) were found to be higher than those for dog dander (3.1x10(-7)+/-1.3x10(-7)min(-1)) and endotoxin (3.6x10(-7)+/-1.6x10(-7)min(-1)). Markers of asthma inflammation including nitrate in exhaled breath condensate (EBC) and exhaled nitric oxide (eNO), were correlated with the concentrations of dust mite allergen (Der p 1) (Spearman r=0.598; p-value=0.068 for EBC and Spearman r=0.819; p-value=0.007 for eNO) and cat dander (Fel d 1) (Spearman r=0.917; p-value=0.0002 for EBC and Spearman r=0.697; p-value=0.054 for eNO) present in PM(10) samples.