Quantification of house dust mite allergens in ambient air

The house dust mites Dermatophagoides pteronyssinus and Dermatophagoides farinae are important sources of indoor allergens. In sensitized patients, house dust mites induce and exacerbate diseases like asthma bronchiale, rhinitis, and conjunctivitis. The most significant exposure of persons occurs overnight in bed and to a lesser extent, during the daytime while performing activities like vacuum cleaning or bed making. In general, house dust mite antigens are quantified in samples of reservoir dust of carpets or beds. Yet, assessing allergens in ambient air would better represent human exposures because inhalation is the main route of uptake, and a close correlation between levels of floor and air antigens has not yet been proved. Unfortunately, because of extremely low airborne particle concentrations, analyses are difficult to perform and depend on sophisticated sampling strategies, as well as on sensitive immunometric detection assays. Using monoclonal immunoassays, house dust mite antigens, quantified in undisturbed conditions in ambient air, are found at pg/m3 levels. The disturbance of reservoir dust by vacuum cleaning or bed making increases the airborne allergen levels up to ng/m3 concentrations. In this review, we discuss the current knowledge regarding the analysis of airborne house dust mites in both undisturbed and disturbed ambient air. The advantages and disadvantages of different sampling strategies are outlined.