Detection of inhaled Der p 1

Background Measurement of personal exposure to Der p 1 aeroallergen has pre viously been limited by the low quantity of material collected by sampling systems and the assay sensitivity. This has meant that exposure could only be detected if long sampling periods were used or reservoir dust was artifi cially disturbed. We have developed a sampling method to sample true person al exposure and combined it with a novel method which is sensitive enough t o measure allergen exposure over shorter time frames. Objective To describe normal domestic exposure to dust mite allergen during a range of activities in houses in Sydney, Australia. Methods Inhaled particles containing mite allergen Der p 1 were collected u sing a nasal air sampler which impacts particles (> approximate to 5 mu m) onto a protein-binding membrane coated with a thin, porous, adhesive film. The allergen is bound to the membrane in the immediate vicinity of the part icle and detected by immunostaining with monoclonal antibodies specific for Der p. In addition, samples were collected using a standard Institute of O ccupational Medicine (IOM) personal air sampler and the amount of eluted De r p 1 was assayed by ELISA. Results The median number (range) of inhaled particles containing Der p 1 c ollected in each 10-min sampling period was: dust raising 5 (2-10); lying i n bed, 0 (0-2); sitting on the bed, 1 (0-2); walking around the bedroom, 0 (0-2). This represented 0-5.1% of all particles captured. The Der p 1 conce ntration of floor and bed dust was 19.4 and 55.1 mu g/g, respectively. The standard IOM personal sampler and ELISA were unable to detect Der p 1 for a ny of the activities performed. Conclusions We were able to count individual allergen-carrying particles in haled over short time periods, during different domestic exposure situation s. This will offer new insight into several aspects of personal allergen ex posure.