Cross-reactivity of Tyrophagus purtescentiae with Dermatophagoides farinae and Dermatophagoides pteronyssinus in urban areas

Background: Tyrophagus putrescentiae (TP) have cohabited with D. pteronyssinus (DP) and D, farinae (DF) in more than 25% of houses in urban areas of Korea, and many atopic subjects have also been cosensitized to TP and Dermatophagoides species. Objective: We evaluated the cross-reactivity of TP with DF and DP in atopic subjects of urban inhabitants. Methods: The cross-reactivity was evaluated with inhibition ELISA and immunoblotting. Allergenic components of TP were evaluated with IgE immunoblotting of the sera from 25 individual atopics. All enrolled subjects lived in urban areas. Results: In ELISA inhibition with pooled sera, all TP, DP, and DF extract inhibited TP-specific IgE by more than 90%, and the 50% inhibitory concentrations of TP, DP, and DF extract were 0.4 mu g/mL, 0.8 mu g/mL and 0.8 mu g/mL, respectively. The maximum inhibition, however, of DP-specific and DF-specific IgE by TP extracts was 32% and 29%, respectively. With six individual sera, the TP-specific IgE was also inhibited by more than 88% with DF extract in all cases. In inhibition immunoblotting, all of the TP, DP, and DF extracts completely inhibited the TP-specific IgE bands at a concentration of 2.0 mu g/mL. Fifteen allergenic components in TP were found. Among them, the 16-kD allergen was most prevalent (52%) and its IgE binding was completely inhibited by 0.1 mu g/mL of purified Der f2 and it also bound with 2 different monoclonal antibodies to the group 2 allergen of Dermatophagoides species. Conclusions: Our results suggested considerable cross-reactivity between TP and the two Dermatophagoides species in urban areas where TP and Dermatophagoides species cohabit. The 16-kD allergen, which shared common epitopes with the group 2 allergen of Dermatophagoides, is one of the most prevalent allergens of TP.