title: Identification of naive or antigen-experienced human CD8(+) T cells by expression of costimulation and chemokine receptors: analysis of the human cytomegalovirus-specific CD8(+) T cell response.
abstract: Human CMV (HCMV) infection provides an informative model of how long term human CD8(+) T cell memory is maintained in the presence of Ag. To clarify the phenotypic identity of Ag-experienced human CD8(+) T cells in vivo, we determined the expression of costimulation and chemokine receptors on Ag-specific CD8(+) T cells by quantifying individual virus-specific clones in different cell populations using TCR clonotypic probing. In healthy HCMV carriers, expanded CD8(+) clones specific for either HCMV tegument protein pp65 or immediate-early protein IE72 are found in both CD45RO(high) cells and the subpopulation of CD45RA(high) cells that lack the costimulatory molecule CD28. In contrast to previous suggested models of CD8(+) T cell memory, we found that in healthy virus carriers highly purified CD28(-)CD45RA(high)CCR7(-) cells are not terminally differentiated, because following stimulation in vitro with specific HCMV peptide these cells underwent sustained clonal proliferation, up-regulated CD45RO and CCR5, and showed strong peptide-specific cytotoxic activity. In an individual with acute primary HCMV infection, HCMV pp65-specific CD8(+) T cells are predominantly CD28(-)CD45RO(high)CCR7(-). During convalescence, an increasing proportion of pp65-specific CD8(+) T cells were CD28(-)CD45RA(high)CCR7(-). We conclude that naive human CD8(+) T cells are CD28(+)CD45RA(high), express CCR7 but not CCR6, and are predominantly CD27(+) and L-selectin CD62 ligand-positive. The phenotype CD27(+)CD45RA(high) should not be used to identify naive human CD8(+) T cells, because CD27(+)CD45RA(high) cells also contain a significant subpopulation of CD28(-)CD27(+) Ag-experienced expanded clones. Thus CD8(+) T cell memory to HCMV is maintained by cells of expanded HCMV-specific clones that show heterogeneity of activation state and costimulation molecular expression within both CD45RO(high) and CD28(-)CD45RA(high) T cell pools.
authors.affiliation: Department of Medicine, University of Cambridge, Cambridge, United Kingdom. mrw1004@cam.ac.uk
authors.forename: Mark R
authors.initials: MR
authors.lastname: Wills
authors.forename: Georgina
authors.initials: G
authors.lastname: Okecha
authors.forename: Michael P
authors.initials: MP
authors.lastname: Weekes
authors.forename: Maher K
authors.initials: MK
authors.lastname: Gandhi
authors.forename: Patrick J G
authors.initials: PJ
authors.lastname: Sissons
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Carmichael
mesh_terms: D018106:CD28 Antigens / Q000032:analysis*; D018414:CD8-Positive T-Lymphocytes / Q000737:chemistry / Q000276:immunology*; D002454:Cell Differentiation; D003587:Cytomegalovirus / Q000276:immunology*; D003586:Cytomegalovirus Infections / Q000276:immunology; D006801:Humans; D017493:Leukocyte Common Antigens / Q000032:analysis*; D010750:Phosphoproteins / Q000276:immunology; D054400:Receptors, CCR7; D019707:Receptors, Chemokine / Q000032:analysis*; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7 / Q000032:analysis*; D014763:Viral Matrix Proteins / Q000276:immunology
chemical_list: C515370:CCR7 protein, human; D018106:CD28 Antigens; D010750:Phosphoproteins; D054400:Receptors, CCR7; D019707:Receptors, Chemokine; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7; D014763:Viral Matrix Proteins; C065418:cytomegalovirus matrix protein 65kDa; D017493:Leukocyte Common Antigens