Birch allergy and oral allergy syndrome: The practical relevance of serum immunoglobulin E to Bet v 1

Background: Birch allergy (BA) may frequently be associated with fruit-vegetables oral allergy syndrome (OAS). Bet v 1 is the major birch allergen. Previously, it was reported that serum-specific immunoglobulin E (IgE) level could differentiate allergy from sensitization. Thus, this study aimed to investigate the practical role of Bet v 1 IgE. Methods: A total of 245 subjects (128 women, 117 men; mean age, 41 years) with suspected allergic rhinitis and sensitization to Bet v 1 were evaluated. Serum IgE to Bet v 1 was assessed by using immuno-enzymatic. BA and OAS were diagnosed according to validated criteria. Symptom severity perception was measured by the visual analog scale. Results: A total of 158 patients (64.5%) had BA. Patients with BA had higher serum Bet v 1 IgE levels than subjects who were sensitized (p < 0.0001). A cutoff value of 8.94 kUA/L predicted BA (area under the curve, 0.76; odds ratio, 6.18). Fifty-three patients with BA (33.5%) had OAS. Patients positive for OAS had higher Bet v 1 levels (p < 0.0001) and more-severe symptoms (p < 0.0001) than patients with BA and negative for OAS. A cutoff value of 17.4 kUA/L predicted OAS (area under the curve, 0.59; odds ratio, 3.19). Conclusions: The present study demonstrated that serum IgE levels to Bet v 1 could be a useful marker for differentiating between different birch pollen sensitization phenotypes.