Preliminary results of epitope mapping on cross-reactive allergens of cow?Ls milk and soy.

TREJO SEBASTIAN; CANDREVA ANGELA; FERRER-NAVARRO MARIO; AVILES FRANCESC; DOCENA GUILLERMO; PETRUCCELLI SILVANA

Barcelona

Congreso; XXXIV Congreso de la Sociedad Española de Bioquímica y Biología Molecular; 2011

Cow?Ls milk (CM) and soy have became relevant food allergens, mainly due to the high exposition to these allergens in the general population. Besides, soy-based formulas are frequently used substitutes in CM allergic patients under the age of two. However, clinical intolerance has been observed and it may be explained by the cross-reactivity previously described between these allergenic proteins. Bovine caseins and 7S and 11S soy glycinins were described as cross-reactive proteins. Using different assays with monoclonal antibodies (mAb) specific to bovine caseins, we have investigated the antigenic properties of CM and soy proteins. In order to identify the epitopes recognized by these antibodies (linear B epitopes-LBE), purified caseins were enzymatically digested. The resulting peptides were separated by RP-HPLC and analyzed by dot blot using three casein-specific mAbs, and finally they were identified by MALDI-TOF MS. In parallel, antibodies were immobilized onto magnetic beads and afterwards incubated with the peptide mixture previously obtained by proteolysis. MALDI-TOF analysis was performed to compare bound and unbound peptide profiles. Using different proteolytic enzymes we have found that casein-specific mAbs recognize at least three peptides (two on ?¿S1-casein and one on ?¨-casein) all of them containing LBE. The sequence of these peptides has been confirmed by MALDI-TOF/TOF. By means of bioinformatic tools we have found that these immunogenic epitopes are also expressed in different soy allergenic proteins. In conclusion, we have detected CM epitopes that may cross-react with soy allergens. They might constitute potential targets to reduce the allergenicity of soy compounds, or vaccine candidates to develop tolerance in patients with food allergy.