SKIN-PRICK TEST AND RAST RESPONSES TO CEREALS IN CHILDREN WITH ATOPIC-DERMATITIS - CHARACTERIZATION OF IGE-BINDING COMPONENTS IN WHEAT AND OATS BY AN IMMUNOBLOTTING METHOD

Background Hypersensitivity to cereals may occur via inhalation or ing estion. Although cereals are essential in the daily nutrition, only li ttle information is available of the allergens causing symptoms in pat ients with atopic dermatitis (AD). Objective The purpose of the presen t study was to analyse the IgE immune-response to various cereals and specific cereal fractions of wheat and oats in children with severe AD and correlate the results with challenge studies. Methods Skin-prick tests (SPT) with a NaCl suspension of wheat, oats, rice, corn, millet and buckwheat and the ethanol soluble gliadin fraction of wheat were p erformed to 34 wheat/oats challenge positive or negative children with AD. Simultaneously serum total IgE and specific IgE antibody radioall ergosorbent test (RAST), levels to wheat, oats and gluten were determi ned. In addition serum samples of these 34 AD patients and five age ma tched controls were analysed with IgE immunoblotting using neutral and acidic protein extracts of wheat and oats. Results From the 34 AD chi ldren 33 were SPT positive with wheat and 18 with oats. Positive RAST to wheat and oats could be detected in 32 and 30 samples respectively. From the oral wheat challenge positive children 12/14 appeared positi ve with gliadin SPT and revealed positive RAST to gluten, but each of the wheat challenge negative were negative in SPT with gliadin. In imm unoblotting using neutral and acidic fractions of cereals the IgE bind ing with sera of challenge positive children showed the most intensive staining, but no correlation was found between different staining pat terns and the clinical wheat sensitivity. The 26, 38 and 69 kDa bands in wheat and the 46 and 66 kDa in oats could be classified as major Ig E binding proteins of these cereals (> 50 % of the sera were positive) . SPT with rice, corn, millet or buckwheat was positive in 16/34 patie nts. Conclusion Intensive IgE staining to neutral/acidic soluble prote ins in wheat and oats was seen, with major IgE binding to 26, 38 and 6 9 kDa proteins in wheat and 46 and 66 kDa in oats, but no specific IgE staining patterns correlating with clinical cereal sensitivity were f ound. The strong association between the positive oral wheat challenge and the positive SPT with the ethanol soluble gliadin suggests that a lso gliadin is an important allergen in wheat-allergic children with A D. The allergens in rice, corn, millet and buckwheat should be better studied before they can be recommended as alternatives for cereal alle rgic children.