[Detection of IgE antibodies to salt-insoluble wheat proteins in sera of patients with atopic dermatitis by ELISA and immunoblotting techniques].

Specific IgE antibodies against salt-insoluble wheat proteins were investigated in sera from 60 patients with atopic dermatitis (AD) positive to wheat specific CAP-RAST. The salt-insoluble wheat protein fraction was prepared from whole protein fraction of wheat flour, which was extracted by PBS containing 6 M urea. IgE antibodies to salt-insoluble proteins were detected in 15 of the sera. IgE-ELISA was applied to these 15 sera, with whole wheat proteins, salt-soluble proteins, and salt-insoluble proteins used as antigens. Wheat specific CAP-RAST values correlated well with the IgE-ELISA titers against salt-soluble proteins (r = 0.918 p < 0.001). On the other hand, IgE-ELISA titers against both the salt-insoluble proteins and the whole wheat proteins correlated least with CAP-RAST values (r = 0.161 and r = 0.113). The inhibition tests indicated that IgE antibodies against salt-insoluble proteins were different from those against salt-soluble ones. Thus, IgE antibodies to salt-insoluble proteins were another antigen target of IgE-mediated allergy manifestation. To determine the molecular weight of antigens reacting with IgE, IgE-immunoblotting was performed. Several polypeptides with molecular weights of 33-45, 84, 90 and 98 KD were detected. However, the antigen patterns of the blots varied depending on the sera used. These findings suggest that salt-insoluble wheat proteins are the major antigens in some wheat-dependent AD, and that IgE detection against salt-insoluble wheat proteins is important for the diagnosis of wheat allergy.