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Identification of isoform‐specific T‐cell epitopes in the major timothy grass pollen allergen, Phl p 5
Author(s) -
Würtzen P. A.,
Bufe A.,
Wissenbach M.,
Madsen H. O.,
Ipsen H.,
Arnved J.,
Van Neerven R. J. J.
Publication year - 1999
Publication title -
clinical and experimental allergy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.462
H-Index - 154
eISSN - 1365-2222
pISSN - 0954-7894
DOI - 10.1046/j.1365-2222.1999.00652.x
Subject(s) - epitope , t cell receptor , immunology , biology , t cell , recombinant dna , human leukocyte antigen , antigen , microbiology and biotechnology , allergen , t lymphocyte , monoclonal antibody , antibody , immune system , allergy , gene , genetics
Background The involvement of CD4 + T cells in the pathophysiology of atopic disease is well established. Objective To gain further insight into the activation requirements for allergen‐specific T cells, we characterized epitope specificity, HLA restriction and T‐cell receptor (TCR) usage for T cells specific to Phl p 5, the group 5 major allergen of the grass Phleum pratense . Methods To identify the T‐cell epitopes of Phl p 5, three Phl p 5‐specific T‐cell lines (TCLs) and 15 T‐cell clones (TCCs) generated from the peripheral blood of three grass‐allergic patients were tested with recombinant truncated Phl p 5a fragments and synthetic Phl p 5b peptides representing these two different recombinant Phl p 5 isoallergens. Additional activation experiments with HLA‐subtyped antigen‐presenting cells and flow cytometry analysis with TCR V‐specific mAb were performed to further characterize the activation requirements for Phl p 5‐specific TCCs. Results At least nine distinct T‐cell specificities were identified and the T‐cell epitopes recognized differed considerably among the three patients. Most of the epitopes found were isoform‐specific, whereas three epitopes were shared between Phl p 5a and 5b. Several human leucocyte antigen (HLA) class II molecules were involved in the recognition of Phl p 5. Different HLA restriction specificities were even found among TCCs specific to the same epitope region. All TCCs were TCR‐α/β positive, and an overrepresentation of TCR Vβ 3.1 + clones among TCCs specific to Phl p 5 appear to exists as 31% (4/13) of the TCCs expressed TCR Vβ 3.1 (compared with 5% TCR Vβ 3.1 + T cells in human peripheral blood) with no correlation with epitope specificity or HLA restriction. Conclusion The T‐cell reactivity of the three grass‐allergic patients investigated shows that isoallergen‐specific T‐cell epitopes are found throughout the peptide backbone of Phl p 5a and Phl p 5b, and dominant T‐cell epitopes of Phl p 5 were not identified. This indicates that a mixture of at least full‐length rPhl p 5a and rPhl p 5b may be required to target the total Phl p 5‐specific T‐cell response of atopic patients.