IgE binding capacity of synthetic and recombinant peptides of the major storage mite (Lepidoglyphus destructor) allergen, Lep d 2

Background: Lepidoglyphus destructor is an important non-pyroglyphid mite species in Europe and a dominant allergen in fanning 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.