BACKGROUND: The 2S-albumin Ara h 2 is the most potent peanut allergen and a good predictor of clinical reactivity in allergic @entity1 . Posttranslational hydroxylation of @entity1521 residues occurs in DPYSP(OH)S motifs, which are repeated 2 or 3 times in different isoforms. OBJECTIVES: We investigated the effect of @entity1521 hydroxylation on IgE binding and the relative contributions of linear and conformational epitopes to Ara h 2 allergenicity. METHODS: Peptides containing DPYSP(OH)S motifs were synthesized. A  recombinant variant of Ara h 2 without DPYSP(OH)S motifs was generated by means of deletion mutagenesis. IgE reactivity of 18 French and 5 American @entity1 with @entity16244 toward synthetic peptides and recombinant allergens was assessed by using IgE-binding inhibition assays and degranulation tests of humanized @entity35 @entity32651 cells. RESULTS: @entity720 -containing peptides exhibited an IgE-binding activity equivalent to that of the unfolded Ara h 2. In contrast, corresponding peptides without hydroxyprolines displayed a very weak IgE-binding capacity. Despite removal of the DPYSP(OH)S motifs, the deletion variant still displayed Ara h 2 conformational epitopes. The IgE-binding capacity of Ara h 2 was then recapitulated with an equimolar mixture of a hydroxylated peptide and the deletion variant. Hydroxylated peptides of 15 and 27 @entity535 residues were also able to trigger cell degranulation. CONCLUSIONS: Sensitization toward linear and conformational epitopes of Ara h 2 is variable among @entity1 with @entity16244 . Optimal IgE binding to linear epitopes of Ara h 2 requires posttranslational hydroxylation of @entity1521 residues. The absence of hydroxyprolines could then affect the accuracy of component-resolved diagnostics by using rAra h 2.

Allergenicity of peanut component Ara h 2: Contribution of conformational versus linear XXXX -containing epitopes.

@entity1 :: ('9606', 'Species') :: ['children', 'patients'] @entity16244 :: ('MESH:D021183', 'Disease') :: ['peanut allergy'] @entity535 :: ('CHEBI:33704', 'Chemical') :: ['amino acid'] @entity720 :: ('CHEBI:18095', 'Chemical') :: ['Hydroxyproline'] @entity32651 :: ('MESH:D015471', 'Disease') :: ['basophilic leukemia'] @entity35 :: ('10116', 'Species') :: ['rat'] @entity1521 :: ('CHEBI:26271', 'Chemical') :: ['proline']
@entity720 :: (CHEBI:18095,Chemical) :: ['hydroxyproline']
