The Use of Ionizers to Destroy Allergens: Past, Present and Future Research

the significant reductions observed in both rabbit-reactive IgG epitope binding and also human IgE epitope binding. Furthermore, we now have some data on the allergenicity of treated samples in vivo: subjects suffering from pollinosis were found to react less to ion-treated samples in both intracutaneous and conjunctival reaction tests. In future research, identification of the corona product(s) responsible for the destruction of allergens would be the first logical step to take in order to increase the allergen-destroying efficacy of an ionizer. Although Kawamoto et al. state that only two species of ions were generated in their setup (hydrated H 3 O + and O 2 – ), it is known that many highly reactive species are created in this process and each have a different half-life [4–6] . Experiments performed using atmospheres of different pure gases, which would create different corona products, in combination with biochemical techniques to determine the structural and chemical alterations of proteins could aid identification. Once the active species are identified it would then be possible to enhance an ionizer’s production of these species. By increasing the production of active corona products, whilst reducing harmful ozone production (e.g., by heating the corona electrode and modifying the electrode configuration of the ionizer [7] ), the allergen content of the domestic environment could be reduced more efficiently and safely. A trade-off between the maximum amounts of these desired products in the plasma discharge and the unwanted ozone could then be made. Preliminary investigations have already been performed into whether this technique of allergen reduction would translate well into a practical application for the removal of allergens from the domestic environment. The results of chamber tests and in situ, room-scale tests have Although previous research has shown that the allergens Der p 1, Der f 1 and Fel d 1 are destroyed after exposure to corona discharge, it remains to be seen how this occurred [1, 2] . It is essential that we know how these allergens are being inactivated so that we can be sure that they are made safe and to possibly improve the efficacy of the treatment. However, at present, there is a dearth of information on the chemical reactions that occur when proteins encounter the products of corona discharge. In this issue of International Archives of Allergy and Immunology , Kawamoto et al. [3] report on the observed decrease in allergenicity of allergens when treated with positive and negative ions. In this instance, the allergens under study were from Japanese cedar (Cryptomeria japonica) pollen (JCP): Cry j 1 and Cry j 2. In their bench testing, atomized JCP extract was treated with ion-generating devices consisting of a ceramic dielectric plate, a high-voltage applied electrode and an earth electrode in an enclosed experimental system that subjected the atomized JCP solution to the bipolar plasma cluster ions generated on the surface of the ceramic plate. This paper is important as it reveals some clues as to what happens when corona products interact with allergen molecules. Due to the ability of corona products to destroy the structurally different group 1 and group 2 Dermatophagoides allergens and also Fel d 1, it has previously been suggested that the active corona products must follow a broad-spectrum method of destroying proteins, probably affecting the primary structure. In agreement with this are the results of Kawamoto et al.’s biochemical analysis of the treated JCP allergen samples, which shows that the total protein content was degraded when visualized with SDS-PAGE. This complete protein degradation explains Published online: August 29, 2006