Allergenic cross-reactivity, food allergy and pollen.

Pollen-allergic patients frequently present oral allergy-like symptoms after ingestion of several kinds of plant foods. The majority of these reactions are due to three distinct cross-reactive structures that are present in birch pollen. Proteins that share common epitopes with Bet v 1, the major birch pollen allergen, occur in other kinds of tree pollen, apples, stone fruits, celery, carrots and nuts. Approximately 70% of patients who are allergic to birch pollen may experience symptoms after consumption of foods from these groups. In contrast to Bet v 1, two minor allergenic structures which sensitise ≈10-20% of all pollen-allergic patients are also present in grass and weed pollen, namely profilin and cross-reactive carbohydrate determinants. Profilins can induce symptoms to almost all kinds of plant foods, whereas the clinical relevance of IgE binding to ubiquitous carbohydrates of N-glycans from plants remains in doubt. The paper summarises the knowledge pertaining to the molecular features of these cross-reactive structures and the characteristics of the cross-reactivity patterns and discusses aspects of diagnosis, management and routes of sensitisation.