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.