IgE antibodies to aeroallergens in allergic children in São Paulo, Brazil

The sensitization to inhaled allergens was studied in 80 Brazilian children and 12 controls, aged 6 to 16 years. We performed skin tests with Alternaria alternata, cat, dog, Lolium perenne, grasses and the following domestic mites: Blomia tropicalis, Dermatophagoides pteronyssinus, Dermatophagoides farinae, Lepidoglyphus destructor, Chortoglyphus arcutus and Aleuroglyphus ovatus. The frequencies of positive skin tests (mean diameter > or = 23 mm) were respectively 15%, 11%, 11%, 6%, 7%, 95%, 92%, 88%, 76%, 75% and 71%. The mean diameter of the wheal to domestic mites was higher to D. pteronyssinus than to B. tropicalis, L. destructor, A. ovatus and C. arcuatus (p < 0.05). The skin test results to domestic mites by regression analysis revealed highly significant correlation (p < 0.0001), suggesting considerable cross-reactivity between them. Specific IgE to each mite was determined and the results expressed as the mean of the percentage of total counts bound (% TCB). We had the highest levels of % TCB to D. farinae, followed by D. pteronyssinus, E. maynei, B. tropicalis, C. arcuatus, L. destructor and A. ovatus. The Brazilian children with asthma had more positive skin tests to domestic mites than to other inhalant allergens, and based on previous studies performed in São Paulo that have shown D. pteronyssinus and B. tropicalis as the most prevalent mite species in house dust, we assumed that IgE Ab to D. farinae reflects cross-reactivity with D. pteronyssinus in most cases. The observed high levels of IgE Ab to domestic mites stress the importance of environmental avoidance measures, decreasing the rate of sensitization or perhaps the development of symptoms of asthma in genetically predisposed children.