Currently, the detection of crude buckwheat extract-specific
IgE by ImmunoCAP (f11) (Phadia AB, Uppsala, Sweden) is widely used to diagnose buckwheat
allergy. However, the results of this test do not always correlate with the development of allergic symptoms. This study aimed to evaluate the diagnostic usefulness of specific
IgE antibody titers for the major buckwheat
allergens Fag e 1 and Fag e 2. Specific
IgE antibodies were determined using the ImmunoCAP method for native Fag e 1 and Fag e 2, recombinant Fag e 1 and Fag e 2, and crude buckwheat extract (f11) in 10 buckwheat
allergy patients, 14
atopic dermatitis patients, and 15 healthy subjects. All buckwheat
allergy patients showed positive results for native Fag e 1- and Fag e 2-specific
IgE tests and for ImmunoCAP (f11). In contrast, the rates of
atopic dermatitis patients with positive results for native Fag e 1- and Fag e 2-specific
IgE tests were 64.2% (9/14) and 57.1% (8/14), respectively. The sensitivities of the test using
recombinant proteins were lower than those of the test using native
proteins. The area under the curve (AUC) as determined by receiver operating characteristic (ROC) curve analysis was the largest for the native Fag e 2-specific
IgE test (0.967), with a sensitivity of 90% and a specificity of 89.6% (cut-off: 2.74 kUa/L). Thus, the native Fag e 2-specific
IgE antibody titer obtained using the ImmunoCAP method is more reliable than the buckwheat ImmunoCAP (f11) value for predicting buckwheat
allergy.