Contact urticaria and protein contact dermatitis from corn in a patient with serum IgE specific for a salt-soluble corn protein of low molecular weight.

Among the cereals, wheat, rye, barley and oats, have been reported to cause protein contact dermatitis. However, in these cases neither the involvement of an immunological mechanism nor the role of specific protein(s) has been demonstrated. We present a case of protein contact dermatitis from corn. The patient presented with a Type I sensitization to corn, as shown by the presence of specific immunoglobulin (Ig)E and positivity to prick tests with both a flour suspension and the salt-soluble protein fraction of this cereal. The same corn preparations induced a strong urticarial reaction on scratch testing. This reaction was followed several days later by the appearance of erythema and then eczema at the site of application. When boiled, these preparations became inactive on both prick and scratch testing. Patch tests were negative in all cases. Immunoblotting performed with the patient's serum showed the presence of a unique IgE-binding protein band with a molecular weight of around 14 kDa, belonging to the salt-soluble corn protein fraction. Our results give the first clear evidence that cornflour can induce protein contact dermatitis. The IgE-binding 14-kDa protein has characteristics identical to those of the trypsin/alpha-amylase inhibitors from cereals.