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Characterization of indoor home vacuum dust allergens and serum based allergen specific IgE levels in asthmatic and non-asthmatic children
Citation:
WILLIAMS, A. H., T. J. Smith, E. E. HUDGENS, S. W. RHONEY, H. A. OZKAYNAK, R. G. Hamilton, AND J. GALLAGHER. Characterization of indoor home vacuum dust allergens and serum based allergen specific IgE levels in asthmatic and non-asthmatic children. Presented at American Association of Aerosol Research Speciality Conference, San Diego, CA, March 22 - 26, 2009.
Impact/Purpose:
To investigate linkages among allergen exposure, immunological measurements, and asthma, we compared: 1) dust allergen levels in asthmatic versus non-asthmatic homes, 2) the proportion of homes with detectable dust allergens versus the proportion of subjects with detectable allergen specific IgE levels, 3) associations between concentrations of dust allergens and allergen specific IgE, and 4) whether people with detectable levels of allergen specific IgE were more likely to have an asthma diagnosis.
Description:
The Mechanistic Indicators of Childhood Asthma (MICA) study was conducted in the Detroit, Michigan area during fall to early winter 2006-2007. Children from 9-13 years of age were recruited into a cross-sectional study to examine biological markers of exposure, effects, and susceptibility using a source to health outcome (asthma) framework. The children were predominately African American (83.3%) and 47% ofthe subjects were asthmatic. Blood samples from 189 children were analyzed for total and allergen specific IgE analyses including cat and dog epithelial dander, German cockroach, two house dust mites (Dermatophagoides pteronyssisinus-Det P, Dermatophagoidesfarinae-Der f), mouse and rat pests, and four molds (Alternaria alternata, Aspergillusfumatus, Cladosporum herbarum, and Penicillium notatum). Vacuum dust samples from 148 households were sieved to 300 microns and analyzed for 10 allergens. To investigate linkages among allergen exposure, immunological measurements, and asthma, we compared: 1) dust allergen levels in asthmatic versus non-asthmatic homes, 2) the proportion of homes with detectable dust allergens versus the proportion of subjects with detectable allergen specific IgE levels, 3) associations between concentrations of dust allergens and allergen specific IgE, and 4) whether people with detectable levels of allergen specific IgE were more likely to have an asthma diagnosis. Cat and dog dust allergen levels were lower in asthmatic homes as compared to non-asthmatic homes. In contrast, dust mite, cockroach, mouse and Cladosporum allergen levels were higher in asthmatic compared to non-asthmatic homes. All homes had detectable levels ofdust allergens and no child's home had fewer than three dust allergens. Alternaria and Cladosporum were found in >99% of samples with Der f mite occurring in 82%, dog dander in 77%, cat dander in 50%, and cockroach in 10% of the homes. In contrast, only 43% of the subjects had elevated allergen specific IgE levels. The proportions of subjects with elevated allergen specific IgE levels were dust mite (31%), dog (27%), cat (22%), mouse (6%), and rat (5%). No significant correlations were observed between dust allergens and corresponding allergen specific IgE levels except for that of dog dander (r2=0.126, P<0.039). Asthmatic children had significantly higher levels oftotal serum IgE and Phadiatop (combined allergen specific IgE level to a panel of 15 aeroallergens) compared to non-asthmatic children. Additionally, allergen specific IgE levels for cat, dog, cockroach, and all four mold allergens were significantly higher in asthmatic children. Children with detectable levels of serum specific IgE to all molds, house dust mite Der f, German cockroach, and dog and cat danders demonstrated significantly greater probabilities of asthma diagnosis, based on odds ratio tests between asthmatic and non-asthmatic children. Given the general lack of association between dust allergens and corresponding IgE levels, it seems prudent to use allergen specific IgE levels, rather than allergen exposure levels, to investigate impacts of indoor home allergens on asthma ... exacerbation. Characterization of indoor dust allergens, though, would provide information useful for determining the presence of allergens and remediation efforts. This abstract is the text ofa proposed presentation and does not represent EPA policy