Identification of cross-reactive B-cell epitopes between Gly m 5.0101 [Glycine max] and α-casein [Bos Taurus] by epitope mapping - mass spectrometry

ÁNGELA MARÍA CANDREVA; MARIO FERRER-NAVARRO; SILVIA BRONSOMS; ALEJANDRA QUIROGA; RENATA CURCIARELLO; SILVANA PETRUCCELLI; GUILLERMO DOCENA; TREJO SEBASTIÁN

Mar del Plata

Congreso; LXV Reunión Científica Anual de la Sociedad Argentina de Inmunología; 2016

Sociedad Argentina de Inmunología

Cow´s milk proteins are one of the most common causes of food allergyand intolerance in a restricted proportion of IgE-mediated milk allergicpatients treated with soy formulae, due to the cross-allergenicity previouslydescribed. We aimed to characterize cross-reactive epitopes between prevalentsoy and milk allergens using mass spectrometry tools. A bovine casein-specificmonoclonal antibody (1D5 mAb), purified milk caseins (Bos d 8) and therecombinant soy allergen Gly m 5.0101 (rGlym5) were employed to identify linearepitopes by MALDI-TOF MS. The 1D5 mAb was immobilized onto magnetic beads andincubated with the peptide mixture previously obtained by enzymatic digestionof both allergens. The MALDI-TOF MS analysis was performed to compare bound andunbound peptide profiles. Finally, mapped peptides were sequenced de novo byMALDI-TOF to identify dominant epitopes.We showed thatcasein-specific 1D5 mAb recognized 4 peptides on αS1-casein and 3cross-reactive epitopes in rGlym5 of mass: 2260.2 Da (residues 125to142);1993.2 Da (residues 367to385) and 1864.0 Da (residues 527to543).The alignmentof the sequences of these cross-reactivity peptides and peptides of αS1-casein,using the study of occurrence frequency analysis of this epitopes residues (byWebLogo), enables us to identify 4 critical residues charged and neutral (polarand non-polar ) for 1D5 mAb binding. In conclusion, this method identifiedcommon sequential B epitopes and critical aminoacidic between allergens with nophylogenetic relationship. These findings may be relevant for potentialimmunotherapies for patients and led us to understand the clinical intoleranceof milk allergic patients that are exposed to soy formula as dairy substituteduring treatment.