Background: Some patients with a wheat allergy have been reported to
show clinical cross-reactivity to barley. However, it is not clear
whether the development of barley allergy in patients with a wheat
allergy is due to cross-antigenicity between wheat and barley. In our
study, we aimed to determine the clinical cross-reactivity and
immunological cross-antigenicity of wheat and barley. Methods: We
compared the results of barley oral food challenges (OFCs) before oral
immunotherapy (OIT) for wheat with those after OIT in nine patients with
a wheat allergy to estimate the clinical cross-reactivity of wheat and
barley. Moreover, we performed enzyme-linked immunosorbent assay (ELISA)
inhibition and immunoblotting inhibition using serum from seven patients
allergic to wheat and barley. Results: Nine patients who had positive
barley-OFC results performed before OIT for wheat were all negative on
barley-OFC performed after OIT. In ELISA inhibition, preincubation of
serum from patients allergic to wheat and barley with a high barley
extract concentration inhibited binding of IgE to wheat extract by less
than 10%. On the other hand, wheat and barley extracts equally
inhibited binding to barley sIgE at high concentrations. In the
immunoblotting inhibition test, the spots of wheat were inhibited but
weakly by barley extracts, and most of the spots of barley were
inhibited even by low concentrations of the wheat and barley extract.
Conclusion: We showed that barley allergy associated with wheat allergy
is caused by cross-reactivity from wheat. The OIT for wheat was one of
the promising options for barley allergy.
The clinical cross-reactivity and immunological cross-antigenicity of wheat and barley
