title: A functional link for major TCR expansions in healthy adults caused by persistent Epstein-Barr virus infection.
abstract: Dramatic clonal expansions of unknown functional significance have been documented in the T cell receptor (TCR) alpha beta peripheral blood repertoires of apparently healthy adults. In this study, we provide evidence that persistent infection with the ubiquitous Epstein-Barr virus (EBV) causes major distortions within the memory repertoire of healthy virus carriers. Using complementarity determining region 3 (CDR3) length analysis to measure repertoire diversity, dominant expansions that dramatically skewed the entire TCRBV6 blood repertoire towards oligoclonality were enriched in the CD8(+)CD45RO+CD45RA- subset of HLA B8(+) healthy virus carriers. Evidence of phenotypic heterogeneity between individuals was also observed for these expansions based on their variable coexpression of CD45RO and CD45RA. TCR junctional region sequencing revealed that these expansions were clonal and that they represented commonly selected HLA B8-restricted memory cytotoxic T cells that recognize the immunodominant latent EBV epitope, FLRGRAYGL. Furthermore, the functional identity of these virus-specific CD8(+) T cells was confirmed by their FLRGRAYGL-specific cytotoxicity. Therefore, the functional significance of dramatic clonal expansions in healthy adults can be linked in some cases to virus-specific CD8(+) T cells that play an essential role in immunosurveillance. This first identified link for expansions in the circulation of healthy adults strongly implies that restricted-memory TCR responses to environmental antigens play a pivotal role in expansion development, which should have an important impact on studies interpreting TCR expansion patterns in health and disease.
authors.affiliation: Epstein-Barr Virus Unit, Queensland Institute of Medical Research and University of Queensland Joint Oncology Program, Brisbane, Queensland, Australia 4029. sharonS@qimr.edu.au
authors.forename: S L
authors.initials: SL
authors.lastname: Silins
authors.forename: S M
authors.initials: SM
authors.lastname: Cross
authors.forename: K G
authors.initials: KG
authors.lastname: Krauer
authors.forename: D J
authors.initials: DJ
authors.lastname: Moss
authors.forename: C W
authors.initials: CW
authors.lastname: Schmidt
authors.forename: I S
authors.initials: IS
authors.lastname: Misko
mesh_terms: D000328:Adult; D000595:Amino Acid Sequence; D016827:CD8 Antigens; D002353:Carrier State / Q000276:immunology*; D002999:Clone Cells; D015333:Gene Rearrangement, beta-Chain T-Cell Antigen Receptor; D015795:HLA-B8 Antigen; D006566:Herpesviridae Infections / Q000276:immunology*; D004854:Herpesvirus 4, Human / Q000276:immunology*; D006801:Humans; D016056:Immunodominant Epitopes; D007135:Immunoglobulin Variable Region / Q000235:genetics; D007157:Immunologic Surveillance; D017493:Leukocyte Common Antigens; D008213:Lymphocyte Activation; D008875:Middle Aged; D008969:Molecular Sequence Data; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics*; D013602:T-Lymphocytes, Cytotoxic
chemical_list: D016827:CD8 Antigens; D015795:HLA-B8 Antigen; D016056:Immunodominant Epitopes; D007135:Immunoglobulin Variable Region; D016693:Receptors, Antigen, T-Cell, alpha-beta; D017493:Leukocyte Common Antigens