Price, D.A. et al. Avidity for antigen shapes clonal dominance in CD8+ T cell populations specific for persistent DNA viruses. J. Exp. Med. 202, 1349-1361

Human Immunology Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
Journal of Experimental Medicine (Impact Factor: 12.52). 12/2005; 202(10):1349-61. DOI: 10.1084/jem.20051357
Source: PubMed


The forces that govern clonal selection during the genesis and maintenance of specific T cell responses are complex, but amenable to decryption by interrogation of constituent clonotypes within the antigen-experienced T cell pools. Here, we used point-mutated peptide-major histocompatibility complex class I (pMHCI) antigens, unbiased TCRB gene usage analysis, and polychromatic flow cytometry to probe directly ex vivo the clonal architecture of antigen-specific CD8(+) T cell populations under conditions of persistent exposure to structurally stable virus-derived epitopes. During chronic infection with cytomegalovirus and Epstein-Barr virus, CD8(+) T cell responses to immunodominant viral antigens were oligoclonal, highly skewed, and exhibited diverse clonotypic configurations; TCRB CDR3 sequence analysis indicated positive selection at the protein level. Dominant clonotypes demonstrated high intrinsic antigen avidity, defined strictly as a physical parameter, and were preferentially driven toward terminal differentiation in phenotypically heterogeneous populations. In contrast, subdominant clonotypes were characterized by lower intrinsic avidities and proportionately greater dependency on the pMHCI-CD8 interaction for antigen uptake and functional sensitivity. These findings provide evidence that interclonal competition for antigen operates in human T cell populations, while preferential CD8 coreceptor compensation mitigates this process to maintain clonotypic diversity. Vaccine strategies that reconstruct these biological processes could generate T cell populations that mediate optimal delivery of antiviral effector function.

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    • "In this regard, the T cell receptor (TCR) is an excellent marker that allows antigen-specific responses to be followed along T cell differentiation and over time [11]. Thorough analyses of both viral and tumor antigen-specific CD8 T cell responses have revealed that the antigen-specific T cell repertoire is generally composed of highly frequent (also defined as dominant) as well as less frequent (defined as non-dominant) T cell clonotypes [12,13]. Through a process known as TCR clonotype selection, certain clonotypes may become more dominant along T cell differentiation [14-16] or throughout the time course of infection [17]. "
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    ABSTRACT: Persistent viruses are kept in check by specific lymphocytes. The clonal T cell receptor (TCR) repertoire against Epstein-Barr virus (EBV), once established following primary infection, exhibits a robust stability over time. However, the determinants contributing to this long-term persistence are still poorly characterized. Taking advantage of an in vivo clinical setting where lymphocyte homeostasis was transiently perturbed, we studied EBV antigen-specific CD8 T cells before and after non-myeloablative lympho-depleting chemotherapy of melanoma patients. Despite more advanced T cell differentiation, patients T cells showed clonal composition comparable to healthy individuals, sharing a preference for TRBV20 and TRBV29 gene segment usage and several co-dominant public TCR clonotypes. Moreover, our data revealed the presence of relatively few dominant EBV antigen-specific T cell clonotypes, which mostly persisted following transient lympho-depletion (TLD) and lymphocyte recovery, likely related to absence of EBV reactivation and de novo T cell priming in these patients. Interestingly, persisting clonotypes frequently co-expressed memory/homing-associated genes (CD27, IL7R, EOMES, CD62L/SELL and CCR5) supporting the notion that they are particularly important for long-lasting CD8 T cell responses. Nevertheless, the clonal composition of EBV-specific CD8 T cells was preserved over time with the presence of the same dominant clonotypes after non-myeloablative chemotherapy. The observed clonotype persistence demonstrates high robustness of CD8 T cell homeostasis and reconstitution.
    PLoS ONE 10/2013; 8(10):e78686. DOI:10.1371/journal.pone.0078686 · 3.23 Impact Factor
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    • "Polyclonal αPD-1–biotin was obtained from R&D Systems. The fluorescent-peptide–Mamu-A*01 tetrameric complexes central memory 9 (CM9)-PE (Gag, CTPYDINQM; residues 181 to 189) and TL8-PE (Tat, TTPESANL; residues 28 to 35) were produced in house, as described previously (19). "
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    ABSTRACT: Programmed Death-1 (PD-1) expression by human/simian immunodeficiency virus (HIV/SIV)-specific CD8 T cells has been associated with defective cytokine production and reduced in vitro proliferation capacity. However, the cellular mechanisms that sustain PD-1(high) virus-specific CD8 T cell responses during chronic infection are unknown. Here, we show that the PD-1(high) phenotype is associated with accelerated in vivo CD8 T cell turnover in SIV-infected rhesus macaques, especially within the SIV-specific CD8 T cell pool. Mathematical modeling of BrdU labeling dynamics demonstrated a significantly increased generation rate of PD-1(high) compared to PD-1(low) CD8 T cells in all memory compartments. Simultaneous analysis of Ki67 and BrdU kinetics revealed a complex in vivo turnover profile, whereby only a small fraction of PD-1(high) cells, but virtually all PD-1(low) cells, returned to rest after activation. Similar kinetics operated in both chronic and acute SIV infection. Our data suggest that the persistence of PD-1(high) SIV-specific CD8 T cells in chronic infection is maintained in vivo by a mechanism involving high production coupled to high disappearance.
    Journal of Virology 07/2013; 87(17). DOI:10.1128/JVI.01001-13 · 4.44 Impact Factor
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    • "After 7 days, cells were centrifuged, resuspended in PBS supplemented with 1% bovine serum albumin (BSA) and 5 mM EDTA, and stained for 45 min at 4°C with anti-mouse CD8α α-allophycocyanin (ImmunoSource, Halle-Zoersel, Belgium) and influenza NP366–374 tetramer-phycoerythrin (PE). Tetramers were produced by conjugation of soluble biotinylated NP366–374/H-2Db monomeric protein at a 4∶1 molar ratio with PE-conjugated streptavidin as described elsewhere [18]. Dead cells were excluded from flow cytometric analyses using 7AAD (ImmunoSource). "
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    ABSTRACT: Current influenza vaccines fail to induce protection against antigenically distinct virus strains. Accordingly, there is a need for the development of cross-protective vaccines. Previously, we and others have shown that vaccination with whole inactivated virus (WIV) induces cross-protective cellular immunity in mice. To probe the mechanistic basis for this finding, we investigated the role of TLR7, a receptor for single-stranded RNA, in induction of cross-protection. Vaccination of TLR7-/- mice with influenza WIV failed to protect against a lethal heterosubtypic challenge; in contrast, wild-type mice were fully protected. The lack of protection in TLR7-/- mice was associated with high viral load and a relative paucity of influenza-specific CD8+ cytotoxic T lymphocyte (CTL) responses. Dendritic cells (DCs) from TLR7-/- mice were unable to cross-present WIV-derived antigen to influenza-specific CTLs in vitro. Similarly, TLR7-/- DCs failed to mature and become activated in response to WIV, as determined by the assessment of surface marker expression and cytokine production. Plasmacytoid DCs (pDCs) derived from wild-type mice responded directly to WIV while purified conventional DCs (cDCs) did not respond to WIV in isolation, but were responsive in mixed pDC/cDC cultures. Depletion of pDCs prior to and during WIV immunization resulted in reduced numbers of influenza-specific CTLs and impaired protection from heterosubtypic challenge. Thus, TLR7 plays a critical role in the induction of cross-protective immunity upon vaccination with WIV. The initial target cells for WIV appear to be pDCs which by direct or indirect mechanisms promote activation of robust CTL responses against conserved influenza epitopes.
    PLoS ONE 05/2013; 8(5):e63163. DOI:10.1371/journal.pone.0063163 · 3.23 Impact Factor
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