Cross-protection of AIT-induced antibodies to related allergens requires a high degree of structural identity.

In summary, our findings suggest that a relatively high threshold of similarity is required to establish effective cross-blocking antibodies to related allergens. Apparently, the structural identity between Bet v 1 and Mal d 1 is below this threshold. Therefore, this study may explain why immunotherapy with birch pollen allergen often fails to reduce birch pollen-related apple allergy.