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IL-21 is a relatively newly discovered immune-enhancing cytokine that plays an essential role in controlling chronic viral infections. It is produced mainly by CD4(+) T cells, which are also the main targets of HIV-1 and are often depleted in HIV-infected individuals. Therefore, we sought to determine the dynamics of IL-21 production and its potential(More)
Human sialidase (neuraminidase) Neu1 catalyzes lysosomal catabolism of sialylated glycoconjugates. Here we show that during the differentiation of monocytes and the monocytic cell line, THP-1, into macrophages, the majority of Neu1 relocalizes from the lysosomes to the cell surface. In contrast to other cellular sialidases Neu2, Neu3, and Neu4, whose(More)
IL-21 plays an important role in regulating immune response and controlling chronic viral infections. Recently, we reported its decreased serum concentrations and their immunological consequences in HIV-infected persons. In this study, we have investigated how exogenous IL-21 enhances NK cell responses in these persons. We show that the cytokine receptors(More)
As is the case in other viral infections, humans respond to HIV infection by activating their NK cells. However, the virus uses several strategies to neutralize and evade the host's NK cell responses. Consequently, it is not surprising that NK cell functions become compromised in HIV-infected individuals in early stages of the infection. The compromised NK(More)
ADCC is an important immune effector mechanism against tumor and virus-infected cells that can be destroyed by the combined action of specific antibodies of IgG isotype against cell surface-associated antigens and effector cells, predominantly of the NK phenotype. ADCC has been shown to function in vivo in several systems. With regard to HIV, it can be(More)
Interleukin-1 beta (IL-1β) and tumor necrosis factor alpha (TNFα) are potentially important in Chronic Obstructive Pulmonary Disease (COPD), but little is known of the relationships between these cytokines and their antagonists in disease compared with healthy controls. It is unclear if concentrations relate to disease severity. The study aimed to(More)
NK cells play an important role in controlling viral infections. They can kill virus-infected cells directly as well as indirectly via antibody-dependent, cell-mediated cytotoxicity. They need no prior sensitization and expansion for this killing. NK cells are also considered as important regulators of antiviral immune responses. They do so by secreting a(More)
Originally identified as the gamma interferon-inducing factor, interleukin-18 (IL-18) was rediscovered as a proinflammatory cytokine related to the IL-1 family of cytokines that plays an important role in both innate and adaptive immune responses against viruses and intracellular pathogens. Despite its importance in inducing and regulating immune responses,(More)
OBJECTIVE To determine the role of natural cellular cytotoxicity of peripheral blood mononuclear cells (PBMC) in killing of HIV-1 envelope protein-expressing, natural killer (NK)-sensitive human target cells, and to investigate this effector function in HIV-infected individuals. DESIGN AND METHODS An HIV-1 env gene-containing expression vector was(More)
The differentiation of monocytes into macrophages and dendritic cells is accompanied by induction of cell-surface neuraminidase 1 (Neu1) and cathepsin A (CathA), the latter forming a complex with and activating Neu1. To clarify the biological importance of this phenomenon we have developed the gene-targeted mouse models of a CathA deficiency (CathA(S190A))(More)