Identification of the major allergenic components in Blomia tropicalis and the relevance of the specific IgE in asthmatic patients.

Background: Blomia tropicalis has been reported to be a clinically important allergen in house dust. High prevalence of sensitization to B. tropicalis has been noted in asthmatic patients in Taiwan; however, the allergenic components and its impact on asthmatic patients remain to be clarified.

Objective: To analyze the prevalence of IgE against B. tropicalis and each allergenic component in asthmatic patients.

Methods: A series of recombinant allergenic components were used for skin tests. The B. tropicalis specific IgE in the serum were measured using the Pharmacia CAP System and immunoblot analysis.

Results: A total of 131 patients were included in this study: 44% of these 131 patients were allergic to B. tropicalis, 43% of the 80 B. tropicalis-sensitive patients were allergic to Blo t 5, and 75% of the 65 Blo t 5-sensitive patients were allergic to Blo t 5 fragment 3 (Blo t 5 70-117). The sera IgE binding activity to B. tropicalis was repeatedly tested after Dermatophagoides pteronyssinus absorption, and results showed that most patients were concurrently sensitized to D. pteronyssinus and B. tropicalis. In addition, in 2 (18%) of 11 patients, the B. tropicalis sensitization was caused by the cross-reactivity of D. pteronyssinus.

Conclusion: A high prevalence of B. tropicalis sensitization was detected in our asthmatic patients, and most of them were concurrently sensitized to D. pteronyssinus and B. tropicalis. The major allergenic component and its IgE binding fragments in Blo t 5 have been identified. These allergenic components can be used for the allergenic determination in B. tropicalis and for further immunotherapy.