December 12th, 2017
Exposure to allergens derived from house dust mites (eg, Dermatophagoides pteronyssinus) is considered an important factor in the development and exacerbation of asthma. In cultures, more than 95% of mite allergen Der p 1 was associated with mite feces (mean diameter of 22 ± 6 mm; range, 10 to 40 mm).1 Domestic air sampling in bedrooms during dust disturbance showed that greater than 80% of detectable Der p 1 was associated with particles larger than 10 mm and only a small proportion with particles smaller than 5 mm,2,3 the identity of which is not known. To explain how exposure to such large particles (>10 mm) could cause asthma, it was proposed that a low proportion of these large fecal particles would enter the lower airways, and the effects of high local allergen concentrations from each particle, on chronic exposure, might provide sufficient stimulus to maintain or produce hyperreactivity.2 There is also some direct evidence of mite allergen, albeit in low concentrations, in the lungs of asthmatic subjects. We investigated the sources of Der p 1 aeroallergen by using a new technique, which enables individual particles containing allergen to be visualized.