IgE Binding Capacity of Synthetic and Recombinant Peptides of the Major Storage Mite (Lepidoglyphus destructor) Allergen, Lep d 2

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Abstract
Background: Lepidoglyphus destructor is an important non–pyroglyphid mite species in Europe and a dominant allergen in farming environments. The major allergen of L. destructor, Lep d 2, is a protein of 13.2 kD that is recognised by about 90% of sera RAST positive to this mite species. Methods: The cDNA of two isoallergens of the Lep d 2 has previously been sequenced and the protein expressed in different protein expression systems. In order to map the B–cell epitopes, the full length protein and the truncated forms of the protein have been expressed in Escherichia coli as glutathione–S–transferase (GST) fusion proteins. Recombinant Lep d 2 fragments and synthetic overlapping 15 mer peptides spanning Lep d 2 were probed with sera from patients allergic to storage mite. Results: The full–length (125 amino acids) GST fusion protein reacted strongly with patient IgE in Western blots and dot blots. Synthetic peptides failed to react with IgE antibodies from mite–allergic patients and the truncated fusion proteins displayed weak IgE–binding capacity. Conclusion: We conclude that there are no dominant linear IgE–binding epitopes in Lep d 2. Recombinant or synthetic Lep d 2 fragments may, however, be further evaluated as hypoallergenic candidate molecules for specific immunotherapy.