Usefulness of Gly m 4‐specific IgE test in the diagnosis of Rosaceae fruit‐oral allergy syndrome caused by Betulaceae pollen sensitization

Abstract Background Pollen‐food allergy syndrome (PFAS) is caused by the cross‐reaction of the specific IgE to pollen allergens with similar allergens contained in fruits, vegetable, and nuts. The representative allergen responsible for this cross‐reaction is pathogenesis‐related protein (PR)‐10. Specific IgE test using Gly m 4, soybean PR‐10, is widely used to diagnose soy allergy. We aimed to investigate whether the Gly m 4‐specific IgE test is useful for predicting oral allergy symptoms (OAS) to Rosaceae fruits in PFAS caused by Betulaceae pollen sensitization. Methods Forty‐one patients with suspected PFAS were enrolled. Specific IgE levels were measured against alder pollen, apple, peach, pear, and Gly m 4, and correlation between test results and allergic symptoms was assessed to compare the accuracy of these allergen‐specific IgE tests. Results Of the 41 patients, 32 were positive for alder pollen‐specific IgE. Of those, 16 showed OAS to at least one of apple, peach, and pear (OAS (+) group), and the rest 16 cases showed no symptoms (OAS (−) group). The Gly m 4‐specific IgE value was significantly higher in the OAS (+) group (p = .014), and the highest in area under the receiver operating characteristics curve. The cut‐off value for detection of the OAS (+) group was 2.65 UA/ml, with a sensitivity of 62.5% and a specificity of 81.3%. Other allergen‐specific IgE values were not significantly different between the two groups. Conclusions In the subjects sensitized to Betulaceae pollen allergens, the Gly m 4‐specific IgE test is useful for predicting OAS of Rosaceae fruits.