D2.286 - High Prevalence of Clinical Tolerance to Avoided Foods in LTP-Sensitized Patients

Lipid Transfer Proteins (LTPs), particularly Pru p 3, are a major cause of severe IgE-mediated food allergy. Due to high cross-reactivity among LTPs, patients frequently exhibit sensitization to multiple foods without presenting clinical symptoms. Since distinguishing relevant allergy from asymptomatic sensitization is challenging with standard diagnostic tests, the Oral Food Challenge (OFC) remains the gold standard for definitive diagnosis. Therefore, the aim of this study is to evaluate the clinical relevance of sensitization to cross-reactive foods in LTP-sensitized patients using the OFC to distinguish asymptomatic sensitization from true allergy.

We included patients with confirmed plant food allergy due to LTP sensitization with a positive skin prick test (SPT), specific IgE (sIgE) to Pru p 3. A standardized evaluation was performed using component-resolved diagnostics (ALEX). The OFC was proposed to assess the clinical relevance of sensitization in patients classified within the LTP Syndrome group and was directed toward foods currently avoided due to positive test results. OFC were performed in a hospital setting following established protocols, and outcomes were classified as negative when tolerance was demonstrated or positive when objective allergic symptoms occurred (Figure 1).

A total of 106 OFCs were performed in 41 patients, predominantly involving nuts (almond, peanut, hazelnut) (Table 1) avoided largely as a precaution (73.5%) rather than due to prior reactions. Results indicated a high tolerance rate, with 87.8% of challenges being negative. The 12.2% of confirmed positive reactions were significantly associated with comorbidities (asthma and atopic dermatitis) (Table 2). Molecular profiling confirmed universal Pru p 3 sensitization and broad cross-reactivity to other LTPs (e.g., Mal d 3, Ara h 9), with no sensitization to storage proteins (Figure 2).

The findings demonstrate that LTP-sensitized patients have high clinical tolerance to a diverse range of plant foods, despite positive sensitization. This confirms that molecular cross-reactivity rarely translates into broad clinical allergy. Consequently, the OFC is indispensable to prevent unwarranted dietary restrictions across different food groups and to ensure accurate diagnosis.