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Quality and Potency Profile of Eight Recombinant Isoallergens, Largely Mimicking Total Bet v 1‐Specific IgE Binding of Birch Pollen

Christian Seutter von Loetzen et al., Clinical & Experimental Allergy (2019) - PMID: 30706562

Product(s) used in this publication:  Reference Peptides for Targeted Proteomics - SpikeTides™ & SpikeMix™

Abstract

BACKGROUND:

To date, only limited information on structure, expression levels and IgE binding of Bet v 1 variants, which are simultaneously expressed in birch pollen, is available.

OBJECTIVE:

To analyse and compare structure and serum IgE/IgG binding of rBet v 1 variants to Bet v 1.0101.

METHODS:

Recombinant Bet v 1 variants were studied with sera of 20 subjects allergic to birch pollen. Folding, aggregation and solubility of the rBet v 1 variants were analysed to attribute diverging IgE binding to either allergen structure or methodological features. IgE/IgG binding was studied with rBet v 1 in solution or adsorbed to solid phases. Allergen-mediated cross-linking of FcεRI receptors was determined by mediator release of sensitized humanized rat basophil leukaemia cells.

RESULTS:

All variants, except for rBet v 1.0113, were monomeric and had Bet v 1-type conformation. Serum IgE binding to variants adsorbed to solid phase was reduced to 6.6%-36.5% compared with Bet v 1.0101. In contrast, inhibition of IgE binding to Bet v 1.0101 by rBet v 1 variants ranged from 62% to 83%. Similarly, mediator release ranged from 30.7% to 55.2% for all variants and was only clearly reduced for rBet v 1.0301 (10.4%). The IgE-binding potency of rBet v 1 variants representing their native quantities in birch pollen was only slightly lower compared to extract. IgG binding to variants was between 50.9% and 134.5% compared with rBet v 1.0101 (100%).

CONCLUSION AND CLINICAL RELEVANCE:

Bet v 1 variants previously classified as hypoallergenic can exhibit similar functional IgE binding as Bet v 1.0101. Eight rBet v 1 variants largely reproduce total Bet v 1-specific IgE binding of birch pollen extracts. Assay format-dependent variation in IgE-binding properties needs to be considered in the development of diagnostic or therapeutic products.

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