Allergic cross‐reactivity: from gene to the clinic

Abstract

A large number of allergenic proteins have now their complete cDNA sequences determined and in some cases also the 3D structures. It turned out that most allergens could be grouped into a small number of structural protein families, regardless of their biological source. Structural similarity among proteins from diverse sources is the molecular basis of allergic cross‐reactivity. The clinical relevance of immunoglobulin E (IgE) cross‐reactivity seems to be influenced by a number of factors including the immune response against the allergen, exposure and the allergen. As individuals are exposed to a variable number of allergenic sources bearing homologous molecules, the exact nature of the antigenic structure inducing the primary IgE immune response cannot be easily defined. In general, the ‘cross‐reactivity’ term should be limited to defined clinical manifestations showing reactivity to a source without previous exposure. ‘Co‐recognition’, including by definition ‘cross‐reactivity’, could be used to describe the large majority of the IgE reactivity where co‐exposure to a number of sources bearing homologous molecules do not allow unequivocal identification of the sensitizing molecule. The analysis of reactivity clusters in diagnosis allows the interpretation of the patient's reactivity profile as a result of the sensitization process, which often begins with exposure to a single allergenic molecule.

Allergic Rhinitis and its Impact on Asthma (ARIA) 2008*

“…Molecular biology-based approaches have also improved our knowledge on cross-reactivity among allergens (546)(547)(548). The identification of allergens in fruits and vegetables showed IgE cross-reactivities with the important birch pollen allergens Bet v 1 (549) and Bet v 2 (birch profilin; 550-553).…”

Skin prick tests and allergy diagnosis

“…106 Cross-reactivity depends on the type of allergens involved, in particular their structural and sequential similarity. 106 Pan-allergens responsible for cross-reactivity in vegetables are pathogen-related proteins (PRP) and profi llins. 107 For invertebrates, tropomyosin is the most implicated protein.…”

Strategies for prevention and mitigation of hay fever

“…Several allergenic pollen proteins have homologous proteins in fruits and vegetables. Specific IgE to pollen allergens may subsequently cross-react to these food proteins (Ferreira et al 2004). Approximately 50-70% of the hay-fever patients suffer from one or several food allergies and display symptoms upon the ingestion of fresh fruit from members of the Rosaceae family, like apple, cherry, peach and plum, but also celery and carrot (Table 1).…”

“…Approximately 50-70% of the hay-fever patients suffer from one or several food allergies and display symptoms upon the ingestion of fresh fruit from members of the Rosaceae family, like apple, cherry, peach and plum, but also celery and carrot (Table 1). Especially patients who are sensitized to birch pollen are prone to develop food allergy, since the pollen allergen initiates the sensitization to the main allergens in apple and celery (Bohle et al 2003;Ferreira et al 2004;Fritsch et al 1998). For example, 73% of the patients who are sensitized to the major birch allergen Bet v 1 are also reacting to a natural apple extract (Rossi, Monasterolo and Monasterolo 2003).…”