Purification and IgE binding capacity of Der s 3, a major allergen from Dermatophagoides siboney

Background Sensitization to the house dust mite Dermatophagoides siboney has been demonstrated in asthmatic patients. Previously, Dermatophagoides siboney group 1 and group 2 allergens, named Der s 1 and Der s 2, respeetively, have been purified. Objectives The aim of this study was to purify and to study the IgE reactivity of a 30 kDa component, suspected to correspond to group 3 allergens. Methods The protein was purified by affinity chromatography using anti-Der f 3 monoclonal antibodies and semi-preparative SDS-PAGE. The IgE binding capacity of the purified fractions was tested with sera from 106 mite- sensitive asthmatic patients using a modified chemiluminiscent method. Results Affinity chromatography resulted in fractions containing the 30 kDa component which was further purified to homogeneity by SDS-PAGE. Seventythree per cent of the sera showed IgE reactivity to this protein, indicating that it is a major allergen. The protein also reacted with anti Der f 3 polyclonal antibodies and had tryptic activity. There were differences in the reaetivity to Der s 3 according to the age of the patients. Conclusion Based on the frequency of IgE reactions and the reactivity with antibodies directed to Der f 3, it is proposed to name this 30 kDa allergen from D. siboney, Der s 3.