Abstract
Oral allergy syndrome (OAS) is one of the most common IgE-mediated allergic reactions. It is characterized by a number of symptoms induced by the exposure of the oral and pharyngeal mucosa to allergenic proteins belonging to class 1 or to class 2 food allergens. OAS occurring when patients sensitized to pollens are exposed to some fresh plant foods has been called pollen food allergy syndrome (PFAS). In the wake of PFAS, several different associations of allergenic sources have been progressively proposed and called syndromes. Molecular allergology has shown that these associations are based on IgE co-recognition taking place between homologous allergens present in different allergenic sources. In addition, the molecular approach reveals that some allergens involved in OAS are also responsible for systemic reactions, as in the case of some food Bet v 1-related proteins, lipid transfer proteins and gibberellin regulated proteins. Therefore, in the presence of a convincing history of OAS, it becomes crucial to perform a patient’s tailored molecule-based diagnosis in order to identify the individual IgE sensitization profile. This information allows the prediction of possible cross-reactions with homologous molecules contained in other sources. In addition, it allows the assessment of the risk of developing more severe symptoms on the basis of the features of the allergenic proteins to which the patient is sensitized. In this context, we aimed to provide an overview of the features of relevant plant allergenic molecules and their involvement in the clinical onset of OAS. The value of a personalized molecule-based approach to OAS diagnosis is also analyzed and discussed.
Highlights
The term oral allergy syndrome (OAS) describes the rapid onset of symptoms induced by food allergens on the oral and pharyngeal mucosa
In medical dictionaries, syndrome is a term indicating a characteristic combination of symptoms, without a precise reference to its causes and to the mechanism of the symptom onset
In line with this definition, OAS represents a complex of allergy symptoms localized to the mouth and throat, including itching and/ or angioedema of the lips, tongue, palate, ears and throat, accompanied by stinging pain
Summary
The term oral allergy syndrome (OAS) describes the rapid onset of symptoms induced by food allergens on the oral and pharyngeal mucosa. Patients suffering from pollinosis may display PFAS when ingesting some plant-derived foods (Fig. 1) This syndrome is caused by IgE cross-reactive molecules, profilins and Bet v 1-related proteins, shared by inhalant and food allergen sources. Some aspects are still unclear and the positive IgE testing to profilins and/or to Bet v 1-like proteins does not always correspond to clinical reactivity, that is some patients sensitized to pollen allergens react to plant foods after exposure while others do not [45]. Peach and other fruits, as well as tree nuts and peanuts, are the most common foods eliciting allergic reactions in Bet v 1 like sensitized subjects with differences in prevalence related to different geographical areas [87, 88] and to the patient specific profile of IgE recognition [78]. Some of them cause OAS and sometimes laryngeal edema, and even anaphylactic shock such as Act d 1, the major kiwi allergen
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