UvA-DARE ( Digital Academic Repository ) Sensitization Prevalence , Antibody Cross-Reactivity and Immunogenic Peptide Profile of Api g 2 , the Non-Specific Lipid Transfer Protein 1 of Celery

Background: Celery (Apium graveolens) represents a relevant allergen source that can elicit severe reactions in the adult population. To investigate the sensitization prevalence and cross-reactivity of Api g 2 from celery stalks in a Mediterranean population and in a mouse model. Methodology: 786 non-randomized subjects from Italy were screened for IgE reactivity to rApi g 2, rArt v 3 (mugwort pollen LTP) and nPru p 3 (peach LTP) using an allergen microarray. Clinical data of 32 selected patients with reactivity to LTP under investigation were evaluated. Specific IgE titers and cross-inhibitions were performed in ELISA and allergen microarray. Balb/ c mice were immunized with purified LTPs; IgG titers were determined in ELISA and mediator release was examined using RBL-2H3 cells. Simulated endolysosomal digestion was performed using microsomes obtained from human DCs. Results: IgE testing showed a sensitization prevalence of 25.6% to Api g 2, 18.6% to Art v 3, and 28.6% to Pru p 3 and frequent co-sensitization and correlating IgE-reactivity was observed. 10/32 patients suffering from LTP-related allergy reported symptoms upon consumption of celery stalks which mainly presented as OAS. Considerable IgE cross-reactivity was observed between Api g 2, Art v 3, and Pru p 3 with varying inhibition degrees of individual patients’ sera. Simulating LTP mono-sensitization in a mouse model showed development of more congruent antibody specificities between Api g 2 and Art v 3. Notably, biologically relevant murine IgE cross-reactivity was restricted to the latter and diverse from Pru p 3 epitopes. Endolysosomal processing of LTP showed generation of similar clusters, which presumably represent T-cell peptides. Conclusions: Api g 2 represents a relevant celery stalk allergen in the LTP-sensitized population. The molecule displays common B cell epitopes and endolysosomal peptides that encompass T cell epitopes with pollen and plant-food derived LTP. Citation: Gadermaier G, Hauser M, Egger M, Ferrara R, Briza P, et al. (2011) Sensitization Prevalence, Antibody Cross-Reactivity and Immunogenic Peptide Profile of Api g 2, the Non-Specific Lipid Transfer Protein 1 of Celery. PLoS ONE 6(8): e24150. doi:10.1371/journal.pone. 0024150 Editor: Jacques Zimmer, Centre de Recherche Public de la Santé (CRP-Santé), Luxembourg Received May 24, 2011; Accepted August 1, 2011; Published August 29, 2011 Copyright: 2011 Gadermaier et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: The study was supported by the Christian-Doppler Research Association, Biomay AG, Vienna, Austria, and the Italian Ministry of Health – Current Research Program 2009. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The role of Biomay AG in funding the research was via the Christian Doppler Research Association, a government institution partially financed by industrial partners. This does not alter the authors’ adherence to all the PLoS ONE policies on sharing data and materials. * E-mail: Gabriele.Gadermaier@sbg.ac. at