Molecular, immunological, and structural characterization of Phl p 6, a major allergen and P-particle-associated protein from timothy grass (Phleum pratense) pollen

Susanne Vrtala, Sabine Fischer, Monika Grote, Luca Vangelista, Annalisa Pastore, Wolfgang R. Sperr, Peter Valent, Rudolf Reichelt, Dietrich Kraft, Rudolf Valenta

Research output: Contribution to journalArticlepeer-review

68 Citations (Scopus)

Abstract

Due to the wide distribution and heavy pollen production of grasses, ~50% of allergic patients are sensitized against grass pollen allergens, cDNAs coding for two isoforms and four fragments of a major timothy grass (Phleum pratense) pollen allergen, Phl p 6, were isolated by IgE immunoscreening from a pollen expression cDNA library. Recombinant Phl p 6 (rPhl p 6), an acidic protein of 11.8 kDa, was purified to homogeneity as assessed by mass spectrometry and exhibited almost exclusive α-helical secondary structure as determined by circular dichroism spectroscopy. Phl p 6 reacted with serum IgE from 75% of grass pollen-allergic patients (n = 171). IgE binding experiments with rPhl p 6 fragments indicated that the N terminus of the allergen is required for IgE recognition. Purified rPhl p 6 elicited dose-dependent basophil histamine release and immediate type skin reactions in patients allergic to grass pollen. A rabbit antiserum raised against purified rPhl p 6 identified it as a pollen-specific protein that, by immunogold electron microscopy, was localized on the polysaccharide- containing wall-precursor bodies (P-particles). The association of Phl p 6 with P-particles may facilitate its intrusion into the deeper airways and thus be responsible for the high prevalence of IgE recognition of Phl p 6. Recombinant native-like Phl p 6 can be used for in vitro as well as in vivo diagnoses of grass pollen allergy, whereas N-terminal deletion mutants with reduced IgE binding capacity may represent candidates for immunotherapy of grass pollen allergy with a low risk of anaphylactic side effects.

Original languageEnglish
Pages (from-to)5489-5496
Number of pages8
JournalJournal of Immunology
Volume163
Issue number10
Publication statusPublished - Nov 15 1999

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

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