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

• Published in: PloS one Vol. 6; no. 8; p. e24150
• Main Authors: Gadermaier, Gabriele, Hauser, Michael, Egger, Matthias, Ferrara, Rosetta, Briza, Peter, Souza Santos, Keity, Zennaro, Danila, Girbl, Tamara, Zuidmeer-Jongejan, Laurian, Mari, Adriano, Ferreira, Fatima
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 29.08.2011; Public Library of Science (PLoS)
• Subjects: Adolescent; Adult; Agriculture; Allergens; Allergens - chemistry; Allergens - immunology; Allergies; Allergy; Amino Acid Sequence; Analysis; Animals; Antibodies - immunology; Antigen-antibody reactions; Antigenic determinants; Antigens, Plant - chemistry; Antigens, Plant - immunology; Antigens, Plant - metabolism; Apium graveolens; Apium graveolens - immunology; Biology; Carrier Proteins - chemistry; Carrier Proteins - immunology; Celery; Cell Line, Tumor; Child; Cohort Studies; Computer Science; Computer simulation; Cross Reactions; Cross-reactivity; Dendritic cells; Enzyme-linked immunosorbent assay; Epitopes; Epitopes, T-Lymphocyte - immunology; Female; Fluorides; Food allergies; Humans; Hypersensitivity; Hypersensitivity - immunology; Immunization; Immunogenicity; Immunoglobulin E; Immunoglobulin E - immunology; Immunoglobulin G; Immunology; Laboratories; Lipids; Lymphocytes B; Lymphocytes T; Male; Medicine; Methacrylates; Mice; Microsomes; Middle Aged; Models, Molecular; Patients; Peptide Fragments - chemistry; Peptide Fragments - immunology; Peptide Fragments - metabolism; Peptides; Plant Proteins - chemistry; Plant Proteins - immunology; Plant Proteins - metabolism; Pollen; Pollen - immunology; Polyurethanes; Population; Protein Conformation; Proteins; Rats; Reactivity; T cells; Vegetables; Young Adult; Italy; Austria
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0024150

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. 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. 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. 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.