Airborne House Dust Particles and Diesel Exhaust Particles As Allergen Carriers

Background: Indoor suspended particulate matter (SPM) consists of many different types of particles, the vast majority of which are less than 2.5 microm in diameter. The question arises how these particles may contribute to asthma and respiratory symptoms. One possibility is that airborne dust particles act as carriers of allergens into the airways, as several allergens have been found to be associated with inhalable airborne dust particles.

Objective: We studied the presence of three different allergens on the surface of SPM, i.e. Can f 1 (dog), Bet v 1 (birch pollen) and Der p 1 (house dust mite). We also examined the ability of diesel exhaust particulates (DEP) to attach these allergens and Fel d I (cat) in vitro.

Methods: SPM was collected on polycarbonate filters and an immunogold labelling technique was used to detect the allergens on the particles. The specimens were examined in the backscatter mode of a scanning electron microscope. The same technique was used to examine the binding of the allergens to DEP, after exposing DEP to either crude allergen extracts or partly purified allergens.

Results: Both Can f 1 and Bet v 1 allergens were detected on the surface of the soot particles in SPM mixtures, although to a lesser degree than previously found with Fel d 1. Der p 1 (house dust mite), however, did not show any significant binding to SPM particles. Furthermore, DEP had the ability to adsorb all four allergens in vitro, although to a varying extent.

Conclusion: Soot particles in airborne house dust may act as carriers of several allergens in indoor air. Furthermore, DEP has the ability to bind all the four allergens investigated under aqueous conditions in vitro.