Heat-and pepsin-sensitive plant food allergens (PR-10 and profilin) sometimes cause systemic reaction.
To detect the risk factors for systemic reactions induced by labile food allergens.
A retrospective multicenter study was performed on patients with a documented history of systemic allergic reaction to labile plant food allergens and on age-matched controls with a history of oral allergy syndrome (OAS) induced by the same foods. Offending foods, their amount and state (solid or liquid), and potential co-factors (nonsteroidal anti-inflammatory drugs, protonic pump inhibitors, exercise, alcohol, and fasting) were considered.
We studied 89 patients and 81 controls. Sensitization to PR-10 or profilin, IgE to Bet v 1 and/or Bet v 2, and foods causing OAS were similar in the two groups. Twenty patients experienced > 1 systemic allergic reaction. Tree nuts, Rosaceae, Apiaceae and soymilk were the main offending foods. Seventeen (19%) patients were taking a PPI when the systemic reaction occurred (vs 5% in controls; p< 0.025). The ingestion of the offending food in liquid form (soymilk) was frequent among patients (15%) but unusual among controls (2%; p< 0.025). Soy milk-induced systemic reactions were independent of PPI treatment. Fasting and excess of allergen, but not NSAID and exercise, were other relevant co-factors for systemic reactions. Systemic reactions occurred without any identifiable cofactor in 39 (44%) cases.
PR-10- and profilin-induced systemic reactions are facilitated by PPI, ingestion of large amounts of unprocessed foods, and fasting. Soybean beverages represent a risk for PR-10 hypersensitive patients and should be avoided.

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