Natural exposure and serum antibodies to house dust mite of mite-allergic children with asthma in Atlanta

Pyroglyphid mites in house dust are important allergens associated with asthma in Europe, but comparable studies of house dust mites in the homes of patients with asthma have not been done in the United States. We examined the distribution of mites and mite allergen in the houses of 20 mite-sensitive children with asthma in Atlanta and measured IgE antibodies to mite allergens in their sera. One or more dust samples from bedding, bedroom floor, television room floor, or television room furniture from 17 20 houses contained > 10,000 ng of antigen P 1 equivalent per gram of fine dust: amounts ranged from 280 to 230,400 ng/gm. Allergen levels were higher in dust samples from furniture and bedding than from floors. Dust samples obtained from houses in June to September had more mites and mite allergen than those houses sampled in March to April: relative humidity in the room also was higher in June to September. Mite numbers and allergen in floor and furniture samples were correlated with relative humidity in the room and were high when relative humidity was >500: antigen P 1 equivalent was > 10,000 ng/gm in 21 39 such samples. Dermatophagoides pteronyssinus was present in all houses and dominant in 11 20 . D. farinae was found in 17 houses and was dominant in six. All children studied had high IgE antibody with either D. farinae or D. pteronyssinus RAST: 16 of the 20 children also had IgE to antigen P 1. It is likely that the IgE antibody responses in these 20 children with asthma were a direct result of exposure to high levels of mite allergen. We speculate that the mite sensitivity of these children might play a causative role in their asthma. These results also suggest that extracts of both D. farinae and D. pteronyssinus should be used for skin testing and immunotherapy in the United States.