title: Long-term stable expanded human CD4+ T cell clones specific for human cytomegalovirus are distributed in both CD45RAhigh and CD45ROhigh populations.
abstract: T cells play an important role in the control of human CMV (HCMV) infection. Peripheral blood CD4+ T cell proliferative responses to the HCMV lower tegument protein pp65 have been detected in most healthy HCMV carriers. To analyze the clonal composition of the CD4+ T cell response against HCMV pp65, we characterized three MHC class II-restricted peptide epitopes within pp65 in virus carriers. In limiting dilution analysis, we observed high frequencies of pp65 peptide-specific CD4+ T cells, many of which expressed peptide-specific cytotoxicity in addition to IFN-gamma secretion. We analyzed the clonal composition of CD4+ T cells specific for defined HCMV peptides by generating multiple independent peptide-specific CD4+ clones and sequencing the TCR beta-chain. In a given carrier, most of the CD4+ clones specific for a defined pp65 peptide had identical TCR nucleotide sequences. We used clonotype oligonucleotide probing to quantify the size of individual peptide-specific CD4+ clones in whole PBMC and in purified subpopulations of CD45RAhighCD45ROlow and CD45RAlowCD45ROhigh cells. Individual CD4+ T cell clones could be large (0.3-1.5% of all CD4+ T cells in PBMC) and were stable over time. Cells of a single clone were distributed in both the CD45RAhigh and CD45ROhigh subpopulations. In one carrier, the virus-specific clone was especially abundant in the small CD28-CD45RAhigh CD4+ T cell subpopulation. Our study demonstrates marked clonal expansion and phenotypic heterogeneity within daughter cells of a single virus-specific CD4+ T cell clone, which resembles that seen in the CD8+ T cell response against HCMV pp65.
authors.affiliation: Department of Medicine, University of Cambridge Clinical School, Cambridge, United Kingdom.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Weekes
authors.forename: Mark R
authors.initials: MR
authors.lastname: Wills
authors.forename: J G Patrick
authors.initials: JG
authors.lastname: Sissons
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Carmichael
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D018106:CD28 Antigens / Q000096:biosynthesis; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology* / Q000821:virology*; D002455:Cell Division / Q000276:immunology; D002999:Clone Cells; D003587:Cytomegalovirus / Q000276:immunology*; D018984:Epitopes, T-Lymphocyte / Q000276:immunology* / Q000378:metabolism; D000949:Histocompatibility Antigens Class II / Q000235:genetics; D006801:Humans; D007156:Immunologic Memory; D017493:Leukocyte Common Antigens / Q000096:biosynthesis*; D018655:Lymphocyte Count / Q000379:methods; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000276:immunology / Q000378:metabolism; D010750:Phosphoproteins / Q000276:immunology* / Q000378:metabolism; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology* / Q000821:virology*; D013997:Time Factors; D014763:Viral Matrix Proteins / Q000276:immunology* / Q000378:metabolism
chemical_list: D018106:CD28 Antigens; D018984:Epitopes, T-Lymphocyte; D000949:Histocompatibility Antigens Class II; D010446:Peptide Fragments; D010750:Phosphoproteins; D014763:Viral Matrix Proteins; C065418:cytomegalovirus matrix protein 65kDa; D017493:Leukocyte Common Antigens