Sensitization prevalence, antibody cross-reactivity and immunogenic peptide profile of Api g 2, the non-specific lipid transfer protein 1 of celery

PLoS One. 2011;6(8):e24150. doi: 10.1371/journal.pone.0024150. Epub 2011 Aug 29.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Allergens / chemistry
  • Allergens / immunology
  • Amino Acid Sequence
  • Animals
  • Antibodies / immunology*
  • Antigens, Plant / chemistry
  • Antigens, Plant / immunology*
  • Antigens, Plant / metabolism
  • Apium / immunology*
  • Carrier Proteins / chemistry
  • Carrier Proteins / immunology*
  • Cell Line, Tumor
  • Child
  • Cohort Studies
  • Cross Reactions
  • Epitopes, T-Lymphocyte / immunology
  • Female
  • Fluorides
  • Humans
  • Hypersensitivity / immunology
  • Immunization*
  • Immunoglobulin E / immunology
  • Male
  • Methacrylates
  • Mice
  • Middle Aged
  • Models, Molecular
  • Peptide Fragments / chemistry
  • Peptide Fragments / immunology*
  • Peptide Fragments / metabolism
  • Plant Proteins / chemistry
  • Plant Proteins / immunology*
  • Plant Proteins / metabolism
  • Pollen / immunology
  • Polyurethanes
  • Protein Conformation
  • Rats
  • Young Adult


  • Allergens
  • Antibodies
  • Antigens, Plant
  • Api g 2 allergen, celery
  • Art v 3 allergen, Artemisia vulgaris
  • Carrier Proteins
  • Epitopes, T-Lymphocyte
  • Methacrylates
  • Peptide Fragments
  • Plant Proteins
  • Polyurethanes
  • Pru p 3 allergen
  • Sequence (bonding agent)
  • lipid transfer proteins, plant
  • Immunoglobulin E
  • Fluorides