Allergenicity of peanut component Ara h 2: Contribution of conformational versus linear hydroxyproline-containing epitopes.
J Allergy Clin Immunol
; 135(5): 1267-74.e1-8, 2015 May.
Article
em En
| MEDLINE
| ID: mdl-25483599
ABSTRACT
BACKGROUND:
The 2S-albumin Ara h 2 is the most potent peanut allergen and a good predictor of clinical reactivity in allergic children. Posttranslational hydroxylation of proline residues occurs in DPYSP(OH)S motifs, which are repeated 2 or 3 times in different isoforms.OBJECTIVES:
We investigated the effect of proline 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 patients with peanut allergy toward synthetic peptides and recombinant allergens was assessed by using IgE-binding inhibition assays and degranulation tests of humanized rat basophilic leukemia cells.RESULTS:
Hydroxyproline-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 amino acid residues were also able to trigger cell degranulation.CONCLUSIONS:
Sensitization toward linear and conformational epitopes of Ara h 2 is variable among patients with peanut allergy. Optimal IgE binding to linear epitopes of Ara h 2 requires posttranslational hydroxylation of proline residues. The absence of hydroxyprolines could then affect the accuracy of component-resolved diagnostics by using rAra h 2.Palavras-chave
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Glicoproteínas
/
Antígenos de Plantas
/
Albuminas 2S de Plantas
/
Hidroxiprolina
/
Epitopos
Idioma:
En
Ano de publicação:
2015
Tipo de documento:
Article