Human IgE against the major allergen Bet v 1--defining an epitope with limited cross-reactivity between different PR-10 family proteins.
Bottom Line: This provides a potential explanation, at the molecular level, for the differences in recognition of isoforms of Bet v 1 and other allergens in the PR-10 protein family displayed by IgE targeting this epitope.Finally, we present the first high-resolution structure of a human allergen-specific IgE fragment in the single-chain fragment variable (scFv) format.Such studies may aid us in development of better diagnostic tools and guide us in the development of new therapeutic compounds.
Affiliation: Department of Immunotechnology, Lund University, Lund, Sweden.Show MeSH
Related in: MedlinePlus
Mentions: Different Bet v 1-isoforms have shown varying ability to initiate allergic responses 15,16 and not all IgE-binding epitopes may be shared between the different isoforms, a fact that potentially could complicate diagnosis and specific immunotherapy. We therefore profiled the cross-reactivity between our human Bet v 1-specific IgE-derived scFv and three naturally existing Bet v 1-isoforms (Fig.3). All four scFv, including M0418 that was selected on Bet v 1.0102, did bind the major isoform Bet v 1.0101. It was thus not possible to select binders from this combinatorial IgE library without cross-reactivity to Bet v 1.0101, indicating that epitopes carried on this isoform were major contributors in the sensitization of the allergic donors to Bet v 1-like allergens. Notably, all four scFv showed high reactivity with Bet v 1.0102, an isoform suggested to be a naturally occurring hypoallergen (i.e. a naturally existing Bet v 1-isoform with reduced allergenicity) 15,16,39. In contrast, only two of the available Bet v 1-specific scFv, B10 and B13, showed binding to Bet v 1.0112, another naturally existing variant only differing from Bet v 1.0101 by a single amino acid substitution (F62L). Bet v 1.0112 has also been the foundation for design of two hypoallergenic variants, Bet v 1.2595 and Bet v 1.2744 22, carrying 4 and 9 mutations, respectively, to which none of our four scFv showed any detectable binding, supporting their hypoallergenic properties.
Affiliation: Department of Immunotechnology, Lund University, Lund, Sweden.