Molecular variability of group 1 and 5 grass pollen allergens between Pooideae species: implications for immunotherapy

Clin Exp Allergy. 2010 Mar;40(3):505-19. doi: 10.1111/j.1365-2222.2009.03380.x. Epub 2009 Nov 5.


Background: Differences between major allergens from distinct grass species remain to be investigated, both in terms of structure and antigenicity.

Methods: Group 1 and 5 allergens purified from five common Pooideae species were analysed by mass spectrometry (MS). Major histocompatibility complex (MHC) class II-restricted T cell epitopes were identified using predictive algorithms and human leucocyte antigen (HLA)-binding assays. CD4+ T cell reactivity and IgE binding were assessed based on the induction of CD154 expression in peripheral blood mononuclear cells and using competitive ELISA assays, respectively.

Results: MS analysis of group 5 pollen allergens reveals considerable intra- and inter-species variability in amino acid sequence, with 30-50 predominant isoforms found for each species. Differences in the amino acid sequence as well as N- and O-glycosylation contribute to the variability of group 1 allergens, yielding 5-10 main isoforms, depending on the species. Out of 14 MHC class II-restricted T cell epitopes identified within group 1, only one is conserved among the five grass species. Significant differences in binding affinities for HLA-DR molecules result in variable CD4+ T cell recognition of group 1 and 5 allergens purified from the various species. Up to 38% and 85% of patients exhibit seric IgE responses to species-restricted (or semi-restricted) epitopes associated with group 1 or 5 allergens, respectively.

Conclusion: Major pollen allergens from distinct grass species bear both shared and species-restricted T and B cell immune epitopes. When compared with single extracts, a five grass pollen extract is thus more suitable for specific immunotherapy, as it contains a broader repertoire of the IgE epitopes to which patients are sensitized.

MeSH terms

  • Allergens / chemistry*
  • Allergens / classification*
  • Allergens / immunology
  • Allergens / isolation & purification
  • Amino Acid Sequence
  • Animals
  • Antigen-Antibody Reactions
  • Desensitization, Immunologic*
  • Epitopes / chemistry
  • Epitopes / immunology
  • Humans
  • Immunoglobulin E / immunology
  • Leukocytes / immunology
  • Mice
  • Models, Molecular
  • Molecular Sequence Data
  • Peptide Mapping
  • Poaceae / chemistry*
  • Poaceae / classification*
  • Pollen / chemistry*
  • Protein Conformation
  • Species Specificity
  • T-Lymphocytes / immunology


  • Allergens
  • Epitopes
  • Immunoglobulin E