Clinical benefit of component-resolved diagnosis in Japanese birch-allergic patients with a convincing history of apple or peach allergy.

OBJECTIVE: In northern Japan, birch pollen is the major allergen in pollinosis, while oral allergy syndrome (OAS) is caused primarily by apple and peach, and is almost exclusively related to birch pollinosis. To clarify the clinical benefit of allergen-based component-resolved diagnosis (CRD) in Japanese birch-allergic patients with OAS, we present an analysis of IgE profiles in response to crude extracts and recombinant component-resolved allergen to birch pollen and Rosaceae fruits allergens.

METHODS: The sera of 30 patients with birch pollen-related OAS to apple or peach were analyzed for specific IgE reactivity to pathogenesis-related class 10 (PR-10) family (birch: rBet v 1, apple: rMal d 1, and peach: rPru p 1), profilin (birch: rBet v 2 and peach: rPru p 4), and lipid transfer protein (LTP) (apple: rMal d 3 and peach: rPru p 3) allergens, as well as to conventional crude, unfractionated extracts (birch: T3, apple: f49, and peach: f95) using the ImmunoCAP System™. Allergen-specific IgE values <0.35kUA/L were considered negative.

RESULTS: Of the 30 sera CAP-positive for natural birch pollen extract, 28 (93.3%) exhibited specific IgE against Bet v1, and two (6.7%) contained specific IgE against Bet v2. Of the 26 sera of OAS to apple patients, only 17 were positive for specific IgE against f49 extract (65.4%); however, 24 were positive for specific IgE against rMal d 1 (92.3%). Similarly, only 17 of the 23 sera of OAS to peach patients contained specific IgE against the f95 extract (73.9%); however, 22 were positive for specific IgE against rPru p 1 (95.7%).

CONCLUSION: Our data suggest that CRD constitutes a reliable tool for the diagnosis of birch pollen-related OAS.