title: Single-cell analysis of lymphokine imbalance in asymptomatic HIV-1 infection: evidence for a major alteration within the CD8+ T cell subset.
abstract: In this study we investigated at single-cell level by flow cytometry the potential of T cell cytokine production in asymptomatic HIV-1-infected subjects with > 200 CD4 counts and possible correlation with T helper cell depletion and viral load. Mitogen-stimulated peripheral blood mononuclear cells from 32 HIV-1+ patients and 16 healthy subjects were intracytoplasmically stained for IL-2, interferon-gamma (IFN-gamma), IL-4 or IL-10, and the frequency of cytokine-producing cells was assessed in total T cells, CD4, CD8 and CD45RO subsets as well as in CD69+CD3+ gated lymphocytes. HIV-1+ patients, irrespective of their degree of CD4 depletion, exhibited a major increase in IFN-gamma+ CD8 T cells, largely due to CD28- cells, as well as a decrease in the capacity of CD8 T cells to produce IL-2. Patients with > 500 CD4 counts showed a diminished frequency of IL-4 expression in CD4 T cells and a negative correlation was found between this parameter and the ex vivo CD4 counts in the 32 patients. Analysis of patients stratified according to viral load revealed a significantly higher proportion of IL-2-producing CD4 cells in the group with < 5000 RNA copies/ml. In short, using single-cell analysis and an antigen-presenting cell-independent stimulus, we have not been able to find any significant cytokine imbalances in the CD4 subset, suggesting that the well described T helper defects are not due to intrinsic alterations in the potential of CD4 T cells to produce cytokines. On the other hand, the major disturbances in the CD8 T lymphocytes agree with the marked activation and possible replicative senescence of CD8 T cells and emphasize the role of this subset in HIV immunopathogenesis.
authors.affiliation: Faculty of Medicine of Lisbon, Cellular Immunology Unit (CEBIP) and University Hospital of Santa Maria, Portugal.
authors.forename: A E
authors.initials: AE
authors.lastname: Sousa
authors.forename: R M
authors.initials: RM
authors.lastname: Victorino
mesh_terms: D000328:Adult; D018791:CD4 Lymphocyte Count; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry / Q000379:methods; D015658:HIV Infections / Q000276:immunology*; D015497:HIV-1; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis; D016753:Interleukin-10 / Q000096:biosynthesis; D007376:Interleukin-2 / Q000096:biosynthesis; D015847:Interleukin-4 / Q000096:biosynthesis; D017493:Leukocyte Common Antigens / Q000032:analysis; D008213:Lymphocyte Activation; D008222:Lymphokines / Q000096:biosynthesis*; D008297:Male; D008875:Middle Aged; D016176:T-Lymphocyte Subsets / Q000276:immunology* / Q000378:metabolism; D019562:Viral Load
chemical_list: D007376:Interleukin-2; D008222:Lymphokines; D016753:Interleukin-10; D015847:Interleukin-4; D007371:Interferon-gamma; D017493:Leukocyte Common Antigens