Comparison of the frequency of interleukin (IL)-2-, interferon-gamma-, and IL-4-producing T cells in 2 diseases, human immunodeficiency virus types 1 and 2, with distinct clinical outcomes.
ABSTRACT Human immunodeficiency virus (HIV) type 2 infection is associated with a better clinical outcome, slower rates of CD4 T cell decline, and lower viremia than is HIV-1. This study compares HIV-1 and HIV-2 in regard to the percentages of interleukin (IL)-2-, interferon (IFN)-gamma-, and IL-4-producing cells at the single-cell level, as determined by flow cytometry. At a given degree of CD4 T cell depletion, the frequency of T cells able to produce IL-2 is better preserved in HIV-2 than in HIV-1 infection, particularly within the CD4 T cell subset. As described for HIV-1 immunodeficiency, HIV-2-positive patients exhibit a marked expansion of terminally differentiated effector CD8 T cells (CD28(-)CD27(-)IFN-gamma(+)). However, the proportion of CD8 T cells able to simultaneously produce IL-2 and IFN-gamma is higher in HIV-2 disease. Considering the central role of IL-2 as a lymphocyte proliferative and survival factor, these findings provide a possible immunologic basis for the distinct course of HIV-2 immunodeficiency.
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ABSTRACT: HIV-1 and HIV-2 share many similarities including their basic gene arrangement, modes of transmission, intracellular replication pathways and clinical consequences: both result in AIDS. However, HIV-2 is characterised by lower transmissibility and reduced likelihood of progression to AIDS. The underlying mechanistic differences between these two infections illuminate broader issues of retroviral pathogenesis, which remain incompletely understood. Comparisons between these two infections from epidemiological, clinical, virologic and immunologic viewpoints provide a basis for hypothesis generation and testing in this 'natural experiment' in viral pathogenesis. In terms of epidemiology, HIV-2 remains largely confined to West Africa, whereas HIV-1 extends worldwide. Clinically, HIV-2 infected individuals seem to dichotomise, most remaining long-term non-progressors, whereas most HIV-1 infected individuals progress. When clinical progression occurs, both diseases demonstrate very similar pathological processes, although progression in HIV-2 occurs at higher CD4 counts. Plasma viral loads are consistently lower in HIV-2, as are average levels of immune activation. Significant differences exist between the two infections in all components of the immune system. For example, cellular responses to HIV-2 tend to be more polyfunctional and produce more IL-2; humoral responses appear broader with lower magnitude intratype neutralisation responses; innate responses appear more robust, possibly through differential effects of tripartite motif protein isoform 5 alpha. Overall, the immune response to HIV-2 appears more protective against disease progression suggesting that pivotal immune factors limit viral pathology. If such immune responses could be replicated or induced in HIV-1 infected patients, they might extend survival and reduce requirements for antiretroviral therapy. Copyright © 2013 John Wiley & Sons, Ltd.Reviews in Medical Virology 02/2013; · 7.62 Impact Factor
- AIDS (London, England) 04/2014; 28(7):1075-7. · 4.91 Impact Factor
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ABSTRACT: Despite the strong correlation of T-cell CD38 expression with HIV disease progression, evidence linking CD38 expression and dysfunction at the single cell level is scant. Since CD38 memory CD4 T cells, especially those from HIV-infected persons, fail to induce CD154 (CD40L) while responding to a superantigen with interferon (IFN)-γ or interleukin (IL)-2, we aimed to determine if recall responses to cytomegalovirus (CMV) were similarly affected in the CD38 memory CD4 T-cell subpopulation. Peripheral blood mononuclear cells from HIV+ patients and healthy controls were incubated 14 h with CMV antigens, the superantigen Staphylococcus aureus enterotoxin B or medium, and labeled for identification of central memory (TCM) and effector memory (TEM) CD4 T cells, and for the intracellular detection of induced CD154, IFN-γ and/or IL-2 by flow cytometry. Compared with CD38 cells, CD38 TCM cells from patients had less CD40L induction after CMV stimulation, and increased IFN-γ response. Patients' CD38 TEM cells showed a lower IL-2 response, and tended to have a greater IFN-γ response, in which CD154 induction frequently failed. CMV-specific responses of patients' CD38 TCM and TEM cells were dominated by IFN-γ, and almost all IL-2 cells co-expressed IFN-γ. IL-2 responses to the polyclonal activator S. aureus enterotoxin B were also significantly less frequent among CD38 TCM and TEM cells than in CD38 cells. Patients' CD38 memory CD4 T-cell responses to CMV favor the effector cytokine IFN-γ over IL-2, in the context of deficient CD154 induction, which may limit co-stimulation, proliferation and survival.AIDS (London, England) 01/2014; 28(3):311-6. · 4.91 Impact Factor