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CD8+ T-cell recognition of a synthetic epitope formed by t-butyl modification

Reid, Reiss, Redman, James Edward, Rizkallah, Pierre, Fegan, Christopher Daniel, Pepper, Christopher John and Man, Stephen Tzekwung 2015. CD8+ T-cell recognition of a synthetic epitope formed by t-butyl modification. Immunology 144 (3) , pp. 495-505. 10.1111/imm.12398

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Abstract

We set out to clone Bax-specific CD8+ T cells from peripheral blood sam- ples of patients with primary chronic lymphocytic leukaemia. A number of clones were generated using a Bax peptide pool and their T-cell epitope was mapped to two peptides sharing a common 9-amino-acid sequence (LLSYFGTPT), restricted by HLA-A*0201. However, when these T-cell clones were tested against highly purified syntheses (> 95%) of the same peptide sequence, there was no functional response. Subsequent mass spectrometric analysis and HPLC fractionation suggested that the active component in the original crude peptide preparations (77% pure) was a peptide with a tert-butyl (tBu) modification of the tyrosine residue. This was confirmed by modification of the inactive wild-type sequence to gen- erate functionally active peptides. Computer modelling of peptide:HLA- A*0201 structures predicted that the tBu modification would not affect interactions between peptide residues and the HLA binding site. However, these models did predict that the tBu modification of tyrosine would result in an extension of the side chain out of the peptide-binding groove up towards the T-cell receptor. This modified product formed < 1% of the original P603 crude peptide preparation and < 0.05% of the origi- nal 23-peptide mixture used for T-cell stimulation. The data presented here, illustrate the potential for chemical modifications to change the immunogenicity of synthetic peptides, and highlight the exquisite capacity of T-cell receptors to discriminate between structurally similar peptide sequences. Furthermore, this study highlights potential pitfalls associated with the use of synthetic peptides for the monitoring and modulating of human immune responses.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Chemistry
Medicine
Subjects: Q Science > QD Chemistry
Q Science > QR Microbiology > QR180 Immunology
Publisher: Wiley Blackwell
ISSN: 0019-2805
Funders: MRC, Leukaemia Lymphoma Research, Cancer Research Wales, Cardiff University
Date of First Compliant Deposit: 30 March 2016
Date of Acceptance: 30 September 2014
Last Modified: 18 Oct 2019 12:30
URI: http://orca.cf.ac.uk/id/eprint/67727

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