Cross-Reactivity between Major IgE Epitopes of Family 5 Allergens from Dermatophagoides pteronyssinus and Blomia tropicalis.

BACKGROUND: The aim of this work was to understand the molecular features that trigger the cross-reactivity observed between Der p 5 from Dermatophagoides pteronyssinus, Blo t 5 from Blomia tropicalis, and Der f 5 from D. farinae. METHODS: We collected serum from 60 house dust mite (HDM)-allergic patients residing in the Dellys area of Boumerdès province in northern Algeria. The presence of specific IgE to Der p 5, Der f 5, and Blo t 5 was analyzed. We performed in silico analysis of the structure of the different allergens in order to identify epitopes that can elicit the cross-reactivity of the sera. Synthetic peptides corresponding to the linear epitope sequence of Der p 5, Der f 5, and Blo t 5 were used to evaluate its implication in the cross-reactivity between the allergens. We also modified the sequence of the conformational epitope of Der p 5 by site-directed mutagenesis to mimic Blo t 5. RESULTS: Several sera of patients allergic to HDM contained specific IgE antibodies to Der p 5 and Blo t 5. We demonstrated that the linear epitope of Der p 5 and Blo t 5 is not involved in the cross-reactivity of the sera. Furthermore, mutations introduced in the sequence of Der p 5 to mimic Blo t 5 could not modulate the cross-reactivity between them. CONCLUSIONS: The major linear IgE epitopes of Der p 5 and Blo t 5 are involved in species-specific recognition. Our results may be useful for the development of a hypoallergenic vaccine against HDM group 5 allergens.