The European Union CREATE project: a model for international standardization of allergy diagnostics and vaccines.

Allergen measurements are used extensively in the formulation of allergy diagnostics and vaccines, yet no purified international allergen standards are available for calibration purposes. The aims of the European Union CREATE project were to develop international standards with verifiable allergen content. Purified natural and recombinant allergens were analyzed by means of SDS-PAGE, mass spectrometry, circular dichroism spectra, and small-angle x-ray scattering. IgE reactivity was assessed by means of direct RAST, RAST inhibition, immunoblotting, and basophil histamine release with sera from 961 allergic patients. Three recombinant allergens, rBet v 1, rPhl p 5a, and rDer p 2, were structurally indistinguishable from their natural counterparts and showed excellent IgE reactivity suitable for use as certified reference materials. A second tier of allergens (rPhl p 5b, rOle e1, rDer p 1, rDer f 1, and rDer f 2) was identified that could provide suitable candidates for certified reference materials with minor improvements to the recombinant proteins. Only rPhl p 1 was considered unsuitable as a reference material. Quantitative ELISAs were identified that accurately measured each allergen, except for rPhl p 1. The CREATE project has provided a major step forward in allergen standardization and provides a model for the development of a comprehensive panel of international reference preparations that will harmonize allergen measurements worldwide.