Detection of inhaled Der p 1.

Abstract

Measurement of personal exposure to Der p 1 aeroallergen has previously 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 artificially disturbed. We have developed a sampling method to sample true personal exposure and combined it with a novel method which is sensitive enough to measure allergen exposure over shorter time frames. To describe normal domestic exposure to dust mite allergen during a range of activities in houses in Sydney, Australia. Inhaled particles containing mite allergen Der p 1 were collected using a nasal air sampler which impacts particles (> approximately 5 microm) 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 particle and detected by immunostaining with monoclonal antibodies specific for Der p 1. In addition, samples were collected using a standard Institute of Occupational Medicine (IOM) personal air sampler and the amount of eluted Der p 1 was assayed by ELISA. The median number (range) of inhaled particles containing Der p 1 collected in each 10-min sampling period was: dust raising 5 (2-10); lying in 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 concentration of floor and bed dust was 19.4 and 55.1 microg/g, respectively. The standard IOM personal sampler and ELISA were unable to detect Der p 1 for any of the activities performed. We were able to count individual allergen-carrying particles inhaled over short time periods, during different domestic exposure situations. This will offer new insight into several aspects of personal allergen exposure.