Allergen recognition by IgE antibodies is a key event in allergic inflammation. In this study, the IgE IGHV repertoires of individuals with allergy to the major birch pollen allergen, Bet v 1, were analyzed over a four years period of allergen exposure by RT-PCR and sequencing of cDNA. Approximately half of the IgE transcripts represented non-redundant sequences, which belonged to seventeen different IGHV genes. Most variable regions contained somatic mutations but also non-mutated sequences were identified. There was no evidence for relevant increases of somatic mutations over time of allergen exposure. Highly similar IgE variable regions were found after four years of allergen exposure in the same and in genetically non-related individuals. Our results indicate that allergens select and shape a limited number of similar IgE variable regions in the human IgE repertoire.
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