title: Expansion and contraction of HIV-specific CD4 T cells with short bursts of viremia, but physical loss of the majority of these cells with sustained viral replication.
abstract: Chronic infection with the HIV results in poor HIV-specific CD4 T cell proliferation, but more recent analyses using intracellular cytokine staining demonstrated that IFN-gamma-producing, HIV-specific CD4 T cells can be detected for years in HIV-infected subjects. Because it is not known whether the majority of HIV-specific T cells are lost or become dysfunctional, we examined the kinetics of the T cell response over an extended period of time using a panel of 10 HLA-DR tetramers loaded with HIV p24 peptides. Tetramer+ CD4 T cells were present at a relatively high frequency during acute infection, but the size of these populations substantially contracted following suppression of viral replication. Short-term cessation of antiretroviral therapy resulted in a burst of viral replication and concomitant expansion of tetramer+ CD4 T cells, and these populations again contracted following reinitiation of therapy. The kinetics with which these cell populations contracted were characteristic of effector T cells, a conclusion that was supported by their phenotypic (CCR7-CD45RA-) and functional properties (IFN-gamma+). Continued high-level viremia resulted in the physical loss of the majority of tetramer+ CD4 T cells, and the decline of HIV p24-specific CD4 T cells occurred more rapidly and was more substantial than the reduction of total CD4 T cell numbers. We conclude that the population of HIV p24-specific CD4 T cells is initially responsive to changes in the levels of viral Ags, but that the majority of these cells are lost in a setting of chronic viremia.
authors.affiliation: Department of Cancer Immunology & AIDS, Dana-Farber Cancer Institute, Boston MA 02115, USA.
authors.forename: Nilufer
authors.initials: N
authors.lastname: Seth
authors.forename: Daniel
authors.initials: D
authors.lastname: Kaufmann
authors.forename: Timothy
authors.initials: T
authors.lastname: Lahey
authors.forename: Eric S
authors.initials: ES
authors.lastname: Rosenberg
authors.forename: Kai W
authors.initials: KW
authors.lastname: Wucherpfennig
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000473:pathology; D049109:Cell Proliferation; D016655:HIV Core Protein p24 / Q000378:metabolism; D015658:HIV Infections / Q000276:immunology* / Q000473:pathology / Q000821:virology*; D015497:HIV-1 / Q000276:immunology* / Q000502:physiology; D006684:HLA-DR Antigens / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007371:Interferon-gamma / Q000096:biosynthesis; D007700:Kinetics; D008969:Molecular Sequence Data; D020836:Protein Structure, Quaternary; D014766:Viremia / Q000276:immunology* / Q000473:pathology; D014779:Virus Replication
chemical_list: D016655:HIV Core Protein p24; D006684:HLA-DR Antigens; D007371:Interferon-gamma