POLLEN food allergy syndrome (PFAS) affects a significant portion of birch pollen allergy sufferers, with 50-75% experiencing allergic reactions to foods containing proteins similar to Bet v 1, the major allergenic protein in birch pollen. Despite its prevalence, the specific characteristics of patients who develop PFAS have not been well-defined.
A study presented at the European Academy of Allergy & Clinical Immunology (EAACI) Annual Congress 2024 detailed a clinical trial in Canada focusing on patients with moderate to severe birch pollen allergies to better understand PFAS. Researchers compared baseline characteristics between those with and without PFAS using t-tests, Wilcoxon rank sum tests, and chi-square tests. Logistic regression was employed to identify predictors of PFAS, while allergic symptoms were analysed descriptively.
The team found that PFAS was reported by 31% (68 out of 217) of patients. These individuals commonly experienced local itchiness of the mouth and ears after consuming raw apples, peaches, cherries, plums, and almonds, typically within five minutes of ingestion. The majority of these reactions were reported to occur year-round, with no noticeable seasonality. Patients with PFAS showed higher sensitization to birch and Bet v 1, indicated by elevated specific IgE levels (median 7.67 kUa/L for birch vs. 5.11 kUa/L, p=0.014; and median 6.56 kUa/L for Bet v 1 vs. 3.71 kUa/L, p=0.0056). They also had slightly larger skin prick test diameters (median 12.8 mm vs. 11.5 mm, p=0.004).
The study highlighted key patient characteristics associated with a higher probability of PFAS among those with moderate to severe birch pollen allergies. Although limited by potential recall bias and the absence of component allergen-specific IgE data, these findings offer valuable insights for future research. Notably, the low impact of seasonality on PFAS symptoms suggests that future PFAS trials could be conducted outside the birch pollen season, facilitating more comprehensive investigations.
Reference
Maloney K et al. Predictors of birch pollen food allergy syndrome in patients with moderate-severe birch allergy. Poster. EAACI Annual Meeting, 31 May-3 June 2024.
