Identification of soybean proteins that show cross-allergenicity with cow’s milk caseins

CURCIARELLO, RENATA; PETRUCCELLI, SILVANA; DOCENA, GUILLERMO; FOSSATI, A. C.

Rio de Janeiro

Congreso; 13th International Congress of Immunology; 2007

Immunology Society

Identification of soybean proteins that show cross-allergenicity with cow’s milk caseins.   Cow’s milk allergy (CMA) constitutes the main food allergy observed in the pediatric population in Argentina. Besides, soy-based formulas are the nutritional substitute most employed as treatment. However, adverse reactions have been reported in 40% of the treated patients. These rare allergic reactions might be mostly caused by cross-reactive components that share immunodominat epitopes. Our group has previously described the cross-reactivity between the glycinin A5A4B3 and bovine caseins. We aimed to identify additional cross-allergenic soy components since residual immunochemical cross-reactivity was detected when Glycine max L.merr Raiden, a soy variety that naturally lacks of A5A4B3, was studied. Employing immunoenzimatic methods (immunoblotting and ELISA), cow milk specific antibodies (rabbit sera, monoclonal antibodies, IgE–containing sera from cow milk allergic) and several antigens (soybean purified proteins, recombinant full-length and fragmented proteins) we identified the a and b subunits of b-conglycinin (a soybean 7S globulin) as new potential soybean allergens that show cross-reactivity with cow’s milk proteins. This in-vitro reactivity may suggest that this cross–reactivity may be responsible for the intolerance observed in the treated children. Further studies will be necessary to identify inmunodominant epitopes in these soy globulins, in order to design a strategy to reduce the allergenicity of the soybean formula.        Key words: cow milk allergy, soy proteins, IgE, cross–reactivity