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Query: UMLS:C0021051 (immunodeficiency)
 71,517 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Major histocompatibility (MHC)-restricted cytotoxic T-lymphocytes (CTL) kill human immunodeficiency virus (HIV)-infected cells. In addition, activated CD8(+) T-lymphocytes from HIV-infected individuals suppress virus replication in vitro by producing antiviral factor (CAF). The effector mechanism(s) of CAF involves modulation of HIV gene transcription, is non-cytolytic and mediated in part by soluble antiviral factors. Initially, CAF activity was shown to be more vigorous in activated CD8(+) cells and cell free supernatants (SNs) from asymptomatic individuals compared to those with AIDS, suggesting a protective role in vivo. CAF-mediated suppression is also evident in animal models of immunodeficiency virus infection. Several soluble molecules that contribute to non-cytolytic virus suppression have been characterised, including alpha- and beta-chemokines and interleukin-16 (IL-16), but these are distinct from CAF. Two agents possessing certain CAF-like characteristics, modified antithrombin 111 (AT111) and the human alpha-defensins, have been described but their antiviral mechanisms are not fully understood. CAF-secretion may not be virus-specific as similar activity is found in activated CD8(+) cells/SNs from humans and chimpanzees seronegative for HIV-1. Recent data indicates that the secretion of CAF is MHC-restricted and both cytolytic and non-cytolytic mechanisms are mediated by CTL. If the latter is correct, a single appropriate stimulus could be used to enhance both effector mechanisms in vivo. This paper reviews research aimed at characterising HIV-suppressive factors and raises other questions that must be considered for the development of prophylactic and therapeutic strategies leading to the safe and effective control of HIV.
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PMID:CD8+ T-cell-mediated non-cytolytic suppression of human immuno-deficiency viruses. 1276 88

Interleukin-16 (IL-16) was the first described T lymphocyte chemoattractant. It has since been shown that IL-16 also functions as a primer of T cell proliferation, a modulator of inflammatory and immune responses, a stimulus of B cell differentiation and an inhibitor of Human immunodeficiency virus (HIV) replication. Its precursor, Prointerleukin-16 (pro-IL-16), is expressed in both the nucleus and cytoplasm of T cells. Cytoplasmic pro-IL-16 serves as the precursor for mature IL-16 while nuclear pro-IL-16 is associated with G0/G1 cell cycle arrest. Herein, we review the ability of IL-16 to act as both primer and modulator of T lymphocyte growth. The impact of IL-16 on T cell apoptosis is also discussed. Finally, we describe the role of pro-IL-16 as a T lymphocyte cell cycle growth suppressor.
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PMID:The effect of interleukin-16 and its precursor on T lymphocyte activation and growth. 1525 85

Changes in virological and immunological parameters were analysed following structured intermittent interruption of highly active anti-retroviral therapy (HAART) of patients with chronic human immunodeficiency virus (HIV) infection. Parameters analysed were serum levels of the CD8+ T-cell-derived inhibitory molecules interleukin-16 (IL-16), monocyte inhibitory protein-1beta (MIP-1beta) and RANTES ('regulated upon activation, normal T-cell expressed and presumably secreted'), and the enhancer of HIV replication, monocyte chemotactic protein-1 (MCP-1). Twenty-five patients with chronic HIV infection were evaluated during three cycles of intermittent interruptions of therapy (8 weeks on/4 weeks off) in comparison with 20 healthy sex- and age-matched controls. At enrolment, HIV-infected patients showed significantly higher serum concentrations of IL-16 and RANTES, and significantly lower concentrations of MCP-1, than did healthy controls. Levels of MIP-1beta were similar in both groups. Only the serum levels of IL-16 increased significantly in HIV-infected patients after every treatment interruption. However, differences between the CD4+ or CD8+ T-cell counts/microL, HIV loads and serum concentrations of each cytokine at baseline and at the end of the three cycles of intermittent interruptions of therapy were not significant. It was concluded that structured intermittent interruption of HAART for patients with chronic HIV infection did not modify the immunological parameters, including serum levels of CD8+ T-cell-derived inhibitory molecules, or the virus parameters studied. Thus, the findings do not support the use of this treatment modality for the management of HIV-infected patients.
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PMID:Absence of favourable changes in circulating levels of interleukin-16 or beta-chemokine concentration following structured intermittent interruption treatment of chronic human immunodeficiency virus infection. 1564 5

Cross-sectional studies have shown that the capacity of CD8+ cells from human immunodeficiency virus (HIV)-infected patients and simian immunodeficiency virus (SIV) SIVmac-infected macaques to suppress the replication of human and simian immunodeficiency viruses in vitro depends on the clinical stage of disease, but little is known about changes in this antiviral activity over time in individual HIV-infected patients or SIV-infected macaques. We assessed changes in the soluble factor-mediated noncytolytic antiviral activity of CD8+ cells over time in eight cynomolgus macaques infected with SIVmac251 to determine the pathophysiological role of this activity. CD8+ cell-associated antiviral activity increased rapidly in the first week after viral inoculation and remained detectable during the early phase of infection. The net increase in antiviral activity of CD8+ cells was correlated with plasma viral load throughout the 15 months of follow-up. CD8+ cells gradually lost their antiviral activity over time and acquired virus replication-enhancing capacity. Levels of antiviral activity correlated with CD4+ T-cell counts after viral set point. Concentrations of beta-chemokines and interleukin-16 in CD8+ cell supernatants were not correlated with this antiviral activity, and alpha-defensins were not detected. The soluble factor-mediated antiviral activity of CD8+ cells was neither cytolytic nor restricted to major histocompatibility complex. This longitudinal study strongly suggests that the increase in noncytolytic antiviral activity from baseline and the maintenance of this increase over time in cynomolgus macaques depend on both viral replication and CD4+ T cells.
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PMID:Changes in soluble factor-mediated CD8+ cell-derived antiviral activity in cynomolgus macaques infected with simian immunodeficiency virus SIVmac251: relationship to biological markers of progression. 1635 48

Acyclic nucleoside phosphonates are novel class of clinically broadly used antivirotics effective against replication of both DNA viruses and retroviruses including human immunodeficiency virus (HIV). We have investigated their in vitro effects on immune defence mechanisms in human peripheral blood mononuclear cells, with the main emphasis on expression of cytokines which are able to suppress the entry of HIV in cells. Included in the study were prototype acyclic nucleoside phosphonates, i.e. 9-[2-(phosphonomethoxy)ethyl]adenine (PMEA; adefovir), 9-[2-(phosphonomethoxy)ethyl]-2,6-diaminopurine (PMEDAP), (R)-and (S)-enantiomers of 9-[2-(phosphonomethoxy)propyl]adenine [(R)-PMPA; tenofovir] and [(S)-PMPA], and of 9-[2-(phosphonomethoxy)propyl]-2,6-diaminopurine [(R)-PMPDAP] and [(S)-PMPDAP], and their N(6)-substituted derivatives. Some of the compounds were found to substantially enhance secretion of chemokines such as macrophage inflammatory protein-1alpha (MIP-alpha/CCL3), and "regulated on activation of normal T cell expressed and secreted" (RANTES/CCL5). Secretion of MIP-1beta/CCL4 was only marginally increased, whereas production of interleukin-16 (IL-16) and interferon-gamma (IFN-gamma) remained uninfluenced. The most effective proved to be the N(6)-cyclooctyl-PMEDAP, N(6)-isobutyl-PMEDAP, N(6)-pyrrolidino-PMEDAP, N(6)-cyclopropyl-(R)-PMPDAP, and N(6)-cyclopentyl-(R)-PMPDAP derivatives. Remarkably enhanced secretion of chemokines was reached within 2-4 h of the cell culture, and was observed at concentration of 2-5 microM. It may be suggested that acyclic nucleoside phosphonates represent a new generation of antivirotics with combined antimetabolic and therapeutically prospective immunostimulatory properties.
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PMID:Secretion of antiretroviral chemokines by human cells cultured with acyclic nucleoside phosphonates. 1771 49


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