Improving allergen concentration homogeneity for investigating the effect of corona discharge on Der p1 allergen

Air ionisers utilising corona discharge have been commercially available for some time, although clinical trials have shown that these do not improve the health of asthma sufferers. New research has shown that the corona products can actually destroy allergens including the main allergen of the house dust mite Dermatophagoides pteronyssinus; Der p1. Concentration heterogeneity of commonly used sources of allergen and the additional problems that occur with electrostatic studies mean that present methods of allergen preparation are unsatisfactory. This paper describes work that improves the repeatability of tests investigating the effects of ionic bombardment on Der p1 allergen concentration. Initial experimental methods involved the distribution of sieved culture medium over a surface and divided into sectors for concentration analysis but this gave extremely variable data and so any effect of an allergen reduction method could not reliably be assessed. Different methods of distributing the sample are described in this paper, The results show that by dissolving Der p1 samples and using small evaporated aliquots, samples of homogenous concentration can be reliably used in electrostatic investigations. The benefits of using the new evaporated solution method is described with a comparison made between the effect of negative corona discharge on Der p1 using heterogeneous Der p1-containing culture particles and the new technique described in the present paper. Using the new technique of sample preparation, reductions in the Der p1 concentration increased from a significant (P < 0.01) 37.26% after 60 min to 67.37% after 300 min. Using faecal particles, however, led to insignificant (P > 0.05) reductions that ranged from 4.11% to 26.86% after 60 and 300 min, respectively. (C) 2002 Elsevier Science B.V. All rights reserved.