title: Identification of circulating antigen-specific CD4+ T lymphocytes with a CCR5+, cytotoxic phenotype in an HIV-1 long-term nonprogressor and in CMV infection.
abstract: Antigen-specific CD4+ effector T cells primarily provide help for B-cell antibody responses and CD8+ cytotoxic T-lymphocyte (CTL) responses. We have found an expanded population of HIV-1 p24-specific, T-cell receptor V beta 17+, CD4+ T lymphocytes, defined by in vitro proliferative and interferon-gamma responses to a 15-mer Gag peptide, in the peripheral blood of an individual with long-term nonprogressive HIV-1 infection. Ex vivo, these cells were CCR5+ and CCR7-, consistent with an effector/memory function. Surprisingly, these cells highly expressed several proteins characteristic of cytotoxic lymphocytes, including TIA-1 (T-cell intracellular antigen 1; GMP-17/NKG7), granzymes A and B, CD161 (NKRP-1), and CD244 (C1.7/2B4). Following in vitro peptide stimulation, these cells produced interleukin 2 (IL-2) and intracellular CD40L, suggesting possible helper function, in addition to induction of perforin and cytotoxicity. A subset of cytomegalovirus (CMV)-specific CD4+ T cells in healthy adults similarly expressed these CTL markers and CCR5, ex vivo. Furthermore, this distinct subset of CD4+ T cells was significantly elevated in healthy CMV-seropositive adults, compared with CMV-seronegative individuals. These results suggest that CCR5+ CD4+ CTL may be a major effector mechanism of the immune response to viral infections in humans. Moreover, expression of CCR5 may render them particularly susceptible to cytopathic effects during progressive HIV-1 infection.
authors.affiliation: Centre for Immunology, St Vincent's Hospital, and University of New South Wales, Sydney, Australia. j.zaunders@cfi.unsw.edu.au
authors.forename: John J
authors.initials: JJ
authors.lastname: Zaunders
authors.forename: Wayne B
authors.initials: WB
authors.lastname: Dyer
authors.forename: Bin
authors.initials: B
authors.lastname: Wang
authors.forename: Mee Ling
authors.initials: ML
authors.lastname: Munier
authors.forename: Monica
authors.initials: M
authors.lastname: Miranda-Saksena
authors.forename: Rebecca
authors.initials: R
authors.lastname: Newton
authors.forename: John
authors.initials: J
authors.lastname: Moore
authors.forename: Charles R
authors.initials: CR
authors.lastname: Mackay
authors.forename: David A
authors.initials: DA
authors.lastname: Cooper
authors.forename: Nitin K
authors.initials: NK
authors.lastname: Saksena
authors.forename: Anthony D
authors.initials: AD
authors.lastname: Kelleher
mesh_terms: D000328:Adult; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism / Q000821:virology*; D003586:Cytomegalovirus Infections / Q000276:immunology*; D005434:Flow Cytometry; D016655:HIV Core Protein p24 / Q000276:immunology; D015658:HIV Infections / Q000276:immunology*; D015497:HIV-1; D006801:Humans; D016130:Immunophenotyping; D016601:RNA-Binding Proteins / Q000378:metabolism; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000276:immunology / Q000378:metabolism; D019713:Receptors, CCR5 / Q000276:immunology* / Q000378:metabolism; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology / Q000378:metabolism / Q000821:virology
chemical_list: D016655:HIV Core Protein p24; D016601:RNA-Binding Proteins; D016693:Receptors, Antigen, T-Cell, alpha-beta; D019713:Receptors, CCR5; C076751:TIAL1 protein, human