title: Direct ex vivo analysis reveals distinct phenotypic patterns of HIV-specific CD8(+) T lymphocyte activation in response to therapeutic manipulation of virus load.
abstract: Therapeutic intervention with antiretroviral therapy (ART) enables the modulation of HIV virus load and hence provides a unique opportunity to study the consequences of varying antigen load on the phenotype of virus-specific CD8(+) T lymphocytes in a persistent human viral infection. The recent advent of tetrameric peptide / HLA class I complexes has enabled the direct phenotypic characterization of antigen-specific T cell populations ex vivo. Here, we use this technology to examine directly ex vivo the consequences of therapeutic manipulation of HIV virus load on the phenotype of HIV-specific CTL. Our observations show that: (1) distinct sequential activation patterns of CD8(+) T cells are associated with increasing virus load; (2) T cell receptor (TCR) down-regulation without apoptosis represents an early event during the generation of a T cell response in a natural infection and precedes the emergence of two distinct antigen-specific CD8(+) T cell populations which differ in TCR and CD8 expression levels. Clear differences in surface Annexin V staining were observed between these populations. The observation that CTL activation, demonstrated by TCR and CD8 down-regulation, in response to rising levels of virus load, co-segregates with apoptosis only during later stages of the response indicates that antigen-associated cell death is restricted to distinct subpopulations of CTL.
authors: Nuffield Department of Medicine, John Radcliffe Hospital, Oxford, Great Britain. annette.oxenius@ndm.ox.ac.uk
authors: A
authors: A
authors: Oxenius
authors: H F
authors: HF
authors: Günthard
authors: B
authors: B
authors: Hirschel
authors: S
authors: S
authors: Fidler
authors: J N
authors: JN
authors: Weber
authors: P J
authors: PJ
authors: Easterbrook
authors: J I
authors: JI
authors: Bell
authors: R E
authors: RE
authors: Phillips
authors: D A
authors: DA
authors: Price
mesh_terms: D017304:Annexin A5 / Q000032:analysis; D019380:Anti-HIV Agents / Q000494:pharmacology / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects; D016827:CD8 Antigens / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D002478:Cells, Cultured; D002908:Chronic Disease; D015536:Down-Regulation / Q000187:drug effects; D005434:Flow Cytometry; D015658:HIV Infections / Q000188:drug therapy* / Q000276:immunology* / Q000821:virology; D015497:HIV-1 / Q000187:drug effects / Q000276:immunology* / Q000502:physiology; D015395:Histocompatibility Antigens Class I / Q000276:immunology; D006801:Humans; D016130:Immunophenotyping; D008213:Lymphocyte Activation / Q000187:drug effects; D010455:Peptides / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D019562:Viral Load
chemical_list: D017304:Annexin A5; D019380:Anti-HIV Agents; D016827:CD8 Antigens; D015395:Histocompatibility Antigens Class I; D010455:Peptides; D011948:Receptors, Antigen, T-Cell