Birch pollen immunotherapy inhibits anaphylaxis to the cross-reactive apple allergen Mal d 1 in mice.

BACKGROUND:

Cross-reactive apple allergy is a common co-morbidity of birch pollen allergy, caused by the presence of a Bet v 1 homologue allergen in apple, Mal d 1. Treatment of tree pollen hay fever by immunotherapy is well-established, but its effect on the accompanying apple allergy is debated.

OBJECTIVE:

To establish a mouse model of birch pollen induced cross-reactivity to Mal d 1 and investigate the effect of birch pollen immunotherapy on the cross-reactivity to Mal d 1.

METHODS:

Respiratory allergy was induced in Balb/c mice by intraperitoneal exposure to alum-adsorbed birch pollen extract (BPE) in combination with short or prolonged intranasal exposure to BPE. To evaluate the response to Mal d 1, mice were exposed intraperitoneally to Mal d 1. Immunoglobulin responses and cytokine production by splenocytes were measured by ELISA. Allergic symptoms were evaluated by measuring airway hyper-reactivity and hypothermia as a surrogate marker for anaphylaxis. Immunotherapy was performed subcutaneously with alum-adsorbed BPE.

RESULTS:

Mice exposed to BPE develop cross-reactive IgE to Mal d 1. Early after exposure to BPE, this response is still weak and does not yet translate into anaphylaxis. Interestingly, later re-challenge with BPE increased cross-reactivity to a level where Mal d 1 exposure induced anaphylaxis. Cross-sensitization can also be induced by systemic Mal d 1 exposure. Birch pollen immunotherapy significantly reduced the anaphylactic response of mice to Mal d 1.

CONCLUSION & CLINICAL RELEVANCE:

A mouse model mimicking birch pollen induced cross-reactivity to Mal d 1 was successfully established. In this model birch pollen immunotherapy significantly ameliorated the anaphylaxis induced by Mal d 1. Our experimental data suggest that boosting of Mal d 1 recognizing immunoglobulins by BP SCIT is important for the amelioration of apple allergy in human. This article is protected by copyright. All rights reserved.

This article is protected by copyright. All rights reserved.