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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: 13.91). 12/2005; 202(10):1349-61. DOI: 10.1084/jem.20051357
Source: PubMed

ABSTRACT 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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    • "The viability dye Aqua (Invitrogen) was used to eliminate dead cells from the analysis. Fluorescent tetrameric antigen complexes (tetramers) were produced as described previously [31], and included: HLA-A*0201 CMV-pp65-NV9, HLA-A*0201 EBV-BMLF1-GL9 and BRLF1-YV9, HLA-A*1101 EBV-EBNA3B-AK10 and EBNA3B-IK9, HLA-B*0701 CMV-pp65-TM10, HLA-B*0801 EBV-BZLF1-RL8 and EBNA3A-FL9. Overlapping CMV peptides were kindly provided by Dr. Daniel Olive (Centre Paoli Calmettes, Marseille, France). "
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    • "Using FACS sorting of T cells stained with an HLA-A2 MHC tetramer loaded with the immunodominant cytomegalovirus (CMV) peptide NLVPMVATV, we have identified two CMVspecific T cell clones that dramatically expanded after HSCT as shown by both mass sequencing (Fig 2 and Supporting Information Table 3) and flow cytometry (Supporting Information Fig 9) analysis. Both clones displayed the same TCR beta amino acid sequence identical to the CMV-specific sequences previously reported in other patients (V beta 7-6, J beta 1-4, CDR3: CASSLAPGATNEKLFF) (Price et al, 2005; Venturi et al, 2008). Expansion of these CMV-specific clones is consistent with clinical studies reporting the activation of persistent viral infections after HSCT (Afessa & Peters, 2006). "
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