Cross-reactivity studies of a new group 2 allergen from the dust mite Glycyphagus domesticus, Gly d 2, and group 2 allergens from Dermatophagoides pteronyssinus, Lepidoglyphus destructor, and Tyrophagus putrescentiae with recombinant allergens

Background: Dust mites are important inducers of allergic disease. Group 2 allergens are recognized as major allergens in several mite species, includ ing Dermatophagoides pteroronyssinus, Lepidoglyphus destructor, and Tyropha gus putrescentiae. No allergens have thus far been characterized on the mol ecular level from the dust mite Glycyphagus domesticus. Objective: We sought to examine the cross-reactivity among group 2 allergen s of G domesticus, L destructor, T putrescentiae, and D pteronyssinus. Methods: A group 2 allergen from G domesticus, Gly d 2, was cloned and expr essed as a recombinant protein. Cross-reactivity between Gly d 2 and 3 othe r group 2 allergens, Lep d 2,Tyr p 2, and Der p 2, was studied by using ind ividual sera and a serum pool RAST-positive to G domesticus, L destructor, T putrescentiae, and D pteronyssinus. Recombinant allergens were used as in hibitors of IgE binding in immunoblotting experiments. Molecular modeling o n the basis of the Der p 2 structure was carried out for Gly d 2, Lep d 2, and Tyr p 2. Results: Two cDNAs encoding isoforms of Gly d 2 were isolated, but only the Gly d 2.02 isoform was used in this study Sixteen of 17 subjects had IgE t o Gly d 2. The protein sequence of Gly d 2 revealed 79% identity to Lep d 2 and 46% and 41% identity to Tyr p 2 and Der p 2, respectively. Extensive c rossreactivity was demonstrated among Gly d 2, Lep d 2, and Tyr p 2, but li ttle cross-reactivity was found between these allergens and Der p 2. Accord ing to the tertiary structure of Der p 2 and 3-dimensional models of Gly d 2, Lep d 2, and Tyr p 2, differences reside mainly in surface-exposed resid ues. Conclusion: Gly d 2 showed high sequence homology to Lep d 2. Cross-reactiv ity was observed between Gly d 2, Lep d 2, and Tyr p 2, but only limited cr oss-reactivity was demonstrated between these 3 allergens and Der p 2.