Application of a food allergy murine model to study the cross reactivity between allergens from cow`s milk and soybean”

REY, A.; CURCIARELLO, R.; FOSSATI, A. C.; SILVANA PETRUCCELLI; DOCENA, G. H.

Cordoba

Congreso; Congreso Latinoamericano de Inmunología; 2005

Our aim was to demonstrate the in vitro and in vivo cross reactivity between cow milk proteins and soy globulins using a cow milk murine model of food allergy. Cow milk allergy constitutes the most important food allergy in the pediatric population in several regions. Avoidance of the offending allergen is the only efficient treatment. Soy formula are widely used in our country as a dairy substitute. Even in children not previously exposed to soy proteins intolerance to such formula has been observed. BALB/c mice were intraperitoneal sensitized using either a cow milk protein extract (CMP) or soy protein extract (SP) and Al(OH)3 as adjuvant, during a 30 dayimmunization protocol. An oral challenge was performed with CMP or SP a week after the last boost. Serum total and specific antibodies (IgE, total IgG, IgG1and IgG2a) were measured by ELISA and EAST using as antigens: CMP, SP, soy fractions and recombinant soy proteins (A5A4B3 and alpha subunit of the beta conglicinin). Antigenspecific proliferation was carried out using spleen cells. IgE antibodies: mice sensitized with CMP recognized CMP and, with less intensity SP. Mice sensitized with SP only recognized slightly SP.IgG1 antibodies: mice sensitized with CMP recognized CMP and SP. Mice sensitized with SP only recognized  SP.IgG2a antibodies: mice sensitized with CMP recognized CMP and SP (delayed response). Mice sensitized with SP only recognized SP. Controls also showed specific antibodies.SPN from mice sensitized with CMP recognized in vitro CMP and SP fractions.IgG1 antibodies: mice sensitized with CMP recognized SP fractions and recombinant proteins (mainly the 11S fraction and the A5A4B3). Mice sensitized with SP recognized fractions and recombinant proteins.∗In vivo cross reactivity (clinical signs): sensitized mice showed mainly reduced activity, scratching and rubbing of the nouse and head , pili erection after the oral challenge. ∗In vitro cross reactivity: - only serum IgG1 antibodies detected an immunochemical cross reactivity against whole, fractions and recombinant SP in CMP sensitized mice. - serum IgE antibodies from CMP sensitized mice showed only a slightly cross reactivity against SP. IgE antibodies might be bound to IgE receptors on mast cells. - mice sensitized with soy showed a reduced IgE response against CMP and SP. IgE antibodies might be bound to IgE receptors on mast cells. - IgG1 showed a strong response against SP (whole, fractions and recombinant proteins), while CMP were not recognized. - mice sensitized with CMP recognized A5A4B3 stronger than mice sensitized with SP. - proliferation of splenocytes also showed cross reactivity between CMP and SP fractions. Caseins from cow´s milk (previous work) and the A5A4B3 (11S soy globulin fraction) along with the alpha subunit of beta conglicinin (7S soy globulin fraction) seem to be cross reactive components from both protein systems. Food allergy mouse models proved to be useful tools to study both in vivo and in vitro cross reactivity between different allergens.