Characterization of the T-Cell Epitopes of the Major Peach Allergen Pru p 3

Abstract

Background: Pru p 3 is the major peach allergen recognized by more than 90% of peach-allergic individuals of the Mediterranean area. Identification of the dominant Pru p 3 T-cell epitopes can improve our understanding of the immune responses against this protein and could be helpful in the development of hypoallergenic immunotherapy. For this purpose, we examined the phenotypes, specificities and cytokine secretion profiles of proliferating T cells in response to Pru p 3 in peach-allergic individuals. Methods: Peripheral blood mononuclear cells from 15 peach-allergic patients were incubated with Pru p 3. The proliferation of antigen-specific T-cell lines (TCLs) was assessed by tritiated methylthymidine incorporation. T-cell epitopes were identified by analyzing the reactivity of TCLs against 8 overlapping peptides spanning the entire length of Pru p 3. We characterized the phenotype of Pru-p-3-specific TCLs by flow cytometry and analyzed their production of interleukin (IL) 4 and γ-interferon (IFN-γ) by ELISA. Results: Ninety-two Pru-p-3-specific TCLs were isolated (stimulation index ≧5). These TCLs proliferated mainly in response to Pru p 3_12–27 and Pru p 3_57–72. Pru-p-3-specific TCLs were mainly CD4+ (81%) and expressed cell surface CD30. In addition, TCLs produced high levels of IL-4 and low levels of IFN-γ, indicating a Th2 phenotype. Conclusions: Two immunodominant T-cell-reactive regions of Pru p 3 were identified: Pru p 3_12–27 and Pru p 3_57–72. These peptides showed a differential ability to elicit a Th2 response. Taken together, our results provide a better understanding of the immunological T-cell reactivity against Pru p 3.

Sensitization Prevalence, Antibody Cross-Reactivity and Immunogenic Peptide Profile of Api g 2, the Non-Specific Lipid Transfer Protein 1 of Celery

“…Interestingly, Api g 2 and Art v 3 produced considerable numbers of peptides comprising cluster 4, while only a limited number could be assigned to the C-terminal region of Pru p 3. As depicted in Figure 6C, peptide regions generated by endolysosomal proteases perfectly matched previously identified T cell epitopes of Pru p 3 [28], [29], [30]. Interestingly, cluster 1 and 3 which comprised most of the peptides were also shown to harbor the immunodominant and most important T cell epitopes within amino acids 12–27 and 57–75 of Pru p 3 [28], [29].…”

“…In general, Api g 2 and Art v 3 displayed a more congruent profile compared to Pru p 3, particularly in terms of peptide numbers, kinetics, and the absence of sub-cluster 2b which was only observed for Pru p 3. Interestingly, the i n vitro generated peptides of Pru p 3 (cluster 1–3) perfectly matched to recently identified T cell epitopes [28], [29]. The importance of cluster 3 was also unraveled in two recent studies using natural Pru p 3 and microsomes from human or murine dendritic cells [32], [41].…”

“…The panel on the right side shows the number of peptides (indicated by different grey shadings) observed for each cluster during endolysosomal digestion (0.5–48 hours). Black bars on bottom represent previously identified T cell epitopes of Pru p 3 [28], [29].…”

Proteomic‐based Techniques for the Characterization of Food Allergens

“…In the case of CD, research in this direction is more advanced, as a comprehensive inventory of gluten-derived T-cell epitopes has been already outlined (Tye-Din et al, 2010). Multiple peanut Ara h1 T-cell epitopes with defined HLA restriction (DeLong et al, 2011) and two immunodominant T-cellreactive regions of peach Pru p3 have been recently described (Pastorello et al, 2010). It can be expected that in the next future, a large part of the research effort will be focused on the identification of T-cell epitopes of food allergens, in consideration of their effectiveness in inducing oral tolerance and, hence, of the promising utilize in immunotherapy (Tanabe, 2007).…”

Interaction of Allergens, Major Histocompatibility Complex Molecules, and T Cell Receptors: A ‘Ménage à Trois’ That Opens New Avenues for Therapeutic Intervention in Type I Allergy

“…The larger major allergen in ragweed pollen (Amb a 1; 372 aa) contains more than 20 T cell epitopes and 2 major ones [27]. The small non-specific lipid transfer protein Pru p 3 in peach (91 aa) also harbors more than 6 T cell epitopes with 2 major ones [34,41,42]. Hence, in addition to degenerate HLA binding, the diversity in T cell recognition seems to be a common property of highly allergenic molecules.…”