Clinical & Experimental Allergy

Characterization of IgE epitopes of Cuc m 2, the major melon allergen, and their role in cross-reactivity with pollen profilins

Authors


:
Araceli Díaz Perales, Departamento de Biotecnología, Unidad de Bioquímica, E.T.S. Ingenieros Agrónomos, Ciudad Universitaria, 28040 Madrid, Spain.
E-mail: araceli.diaz@upm.es

Summary

Background Plant profilins are described as minor allergens, although with some exceptions in foods such as melon, watermelon or orange. In fact, they could be responsible for many cross-reactions among distantly related species. This is likely to be a consequence of the presence of common epitopes.

Objective To characterize the B epitopes of Cuc m 2, a model of plant food profilin, using phage display techniques and to compare with other profilins, such as those of timothy grass and birch pollen, and human I profilin, to understand the mechanism of cross-reaction among members of this family.

Methods IgE of melon-allergic patients was used to select clones from a phage display 12 mer peptide library. After two rounds of screening, Cuc m 2-specific clones were eluted and the DNA insertion sequenced. The residues of each clone were mapped on the Cuc m 2 surface to define a mimotope, which was also localized on the three-dimensional surfaces of other profilins.

Results Seventeen melon-allergic patients were selected. Sera from each of them recognized the melon profilin, Cuc m 2, but the majority also recognized Phl p 12 or Bet v 2, timothy grass-, and birch-pollen profilins, respectively. A Cuc m 2 mimotope was defined and mapped onto its surface giving the following sequence: S2W3A5Y6D9H10T111P112G113Q114N116M117R121L122. The homologous residues in Phl p 12 and Bet v 2 had almost identical sequences. By contrast, the homologous sequence in human profilin showed many differences.

Conclusions The identified mimotope could be involved in cross-reactions among food and pollen profilins. Many of these cross-reactions observed in the clinical realm could be explained by the presence of a common epitope found in food and pollen allergens. A new strategy of immunotherapy based on this IgE region could be used in alternative immunotherapy strategies.

Cite this as: L. Tordesillas, L. F. Pacios, A. Palacín, J. Cuesta-Herranz, M. Madero and A. Díaz-Perales, Clinical & Experimental Allergy, 2010 (40) 174–181.

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