Neutralizing antibodies inhibit HIV-1 infection of plasmacytoid dendritic cells by an FcγRIIa independent mechanism and do not diminish cytokines production.

Plasmacytoid dendritic cells (pDC) expressing FcγRIIa are antigen-presenting cells able to link innate and adaptive immunity and producing various cytokines and chemokines. Although highly restricted, they are able to replicate HIV-1. We determined the activity of anti-HIV-1 neutralizing antibodies (NAb) and non-neutralizing inhibitory antibodies (NNIAb) on the infection of primary pDC by HIV-1 primary isolates and analyzed cytokines and chemokines production.

[Anti-HIV antibodies: multiple antiviral activities].

Sexual transmission is currently the major route of HIV infection worldwide. Neutralizing antibodies (IgG) have demonstrated their role in the protection from experimental challenge in non-human primate's model. However, these types of antibodies display very specific characteristics and are extremely difficult to induce.

Efficient transfer of HIV-1 in trans and in cis from Langerhans dendritic cells and macrophages to autologous T lymphocytes.

Objective: The chronology of HIV infection in mucosal tissue after sexual transmission is unknown. Several potential HIV target cells are present at these sites, including dendritic cells, macrophages, and CD4(+) T lymphocytes. Dendritic cells and macrophages are antigen-presenting cells (APCs) and are thus involved in cross-talk with T cells.

Neutralizing antibodies inhibit HIV-1 transfer from primary dendritic cells to autologous CD4 T lymphocytes.

Dendritic cells (DCs) support only low levels of HIV-1 replication, but have been shown to transfer infectious viral particles highly efficiently to neighboring permissive CD4 T lymphocytes. This mode of cell-to-cell HIV-1 spread may be a predominant mode of infection and dissemination. In the present study, we analyzed the kinetics of fusion, replication, and the ability of HIV-1-specific Abs to inhibit HIV-1 transfer from immature DCs to autologous CD4 T lymphocytes.

Stimulation of HIV-1 replication in immature dendritic cells in contact with primary CD4 T or B lymphocytes.

Sexual transmission is the major route of HIV-1 infection worldwide. Dendritic cells (DCs) from the mucosal layers are considered to be the initial targets of HIV-1 and probably play a crucial role in HIV-1 transmission. We investigated the role of cell-to-cell contact between HIV-1-exposed immature DCs and various lymphocyte subsets in the stimulation of HIV-1 replication.

Antibody-Mediated Fcγ Receptor-Based Mechanisms of HIV Inhibition: Recent Findings and New Vaccination Strategies.

The HIV/AIDS pandemic is one of the most devastating pandemics worldwide. Today, the major route of infection by HIV is sexual transmission. One of the most promising strategies for vaccination against HIV sexual infection is the development of a mucosal vaccine, which should be able to induce strong local and systemic protective immunity.

Nonneutralizing antibodies are able to inhibit human immunodeficiency virus type 1 replication in macrophages and immature dendritic cells.

Only five monoclonal antibodies (MAbs) neutralizing a broad range of primary isolates (PI) have been identified up to now. We have found that some MAbs with no neutralizing activities according to the "conventional" neutralization assay, involving phytohemagglutinin-stimulated peripheral blood mononuclear cells as targets, efficiently inhibit the replication of human immunodeficiency virus type 1 (HIV-1) PI in macrophages and immature dendritic cells (iDC). The mechanism of inhibition is distinct from the neutralization of infectivity occurring via Fab fragments and involves the interaction of the F portion with the FcgammaRs present on macrophages and iDC.

Efficient inhibition of HIV-1 replication in human immature monocyte-derived dendritic cells by purified anti-HIV-1 IgG without induction of maturation.

During mucosal HIV transmission, immature dendritic cells (DCs) present in the mucosa are among the first cellular targets of the virus. Previous studies have analyzed the inhibition of HIV-1 transfer from human mature DCs to T lymphocytes by neutralizing IgG, but so far no in vitro data regarding the capacity of antibodies to inhibit HIV-1 infection of immature DCs have been reported. Here, we found an increased HIV-inhibitory activity of monoclonal IgG and purified polyclonal IgG when immature monocyte-derived dendritic cells (iMDDCs) were used as target cells instead of autologous blood lymphocytes.

Involvement of Fc gamma RI (CD64) in the mechanism of HIV-1 inhibition by polyclonal IgG purified from infected patients in cultured monocyte-derived macrophages.

The aim of this study was to investigate the mechanism of HIV-1 neutralization using monocyte-derived macrophages (MDM) in comparison to PBMC as target cells. For this purpose, we analyzed neutralizing activities of different human polyclonal IgG samples purified from sera of HIV-1-infected individuals using a single cycle infection assay. We found an increase of the neutralizing titer when macrophages vs PBMC were used as target cells.

VEGF-induced HUVEC migration and proliferation are decreased by PDE2 and PDE4 inhibitors.

Migration and proliferation of endothelial cells in response to VEGF play an important role in angiogenesis associated to pathologies such as atherosclerosis, diabetes and tumor development. Elevation of cAMP in endothelial cells has been shown to inhibit growth factor-induced proliferation. Our hypothesis was that inactivation of cAMP-specific phosphodiesterases (PDEs) would inhibit angiogenesis.

Signal transduction pathways of taxanes-induced apoptosis.

Docetaxel (Taxotere) is a member of the taxane class of anticancer agents to reach clinical use. This semisynthetic analog of paclitaxel (Taxol) is one of the newer potent anti-neoplastic agents now undergoing extensive laboratory and clinical investigations. Several studies indicate that antimicrotubule agents are potent promoters of apoptosis in cancer cells.

Hepatocyte ploidy in normal young rat.

The aim of the present study was to examine the relation between hepatocyte size and ploidy in Sprague-Dawley rat liver. Therefore, subpopulations of hepatocytes of various sizes were separated from the isolated crude hepatocyte population either mechanically or by using centrifugal elutriation. Hepatocyte size was determined on scanning electron microscopy photographs.

Effects of combinations of 7beta-hydroxycholesterol and anticancer drugs or ionizing radiation on the proliferation of cultured tumor cells.

Oxysterols compose a large class of natural substances endowed in a number of cases with marked antiproliferative and cytotoxic activities. The consequences of treatments combining 7beta-hydroxycholesterol (7beta-OHC) or XG-142 (a galactose-linked hydrosoluble derivative of 7beta-OHC) with drugs used in cancer chemotherapy or gamma radiation has been evaluated upon a variety of tumor cell lines: Hep-G2, U937, K562 cells, its adriamycin-resistant variant K562 Adr+ and RDM4. Proliferation was assessed by the Uptiblue assay and the [3H]Thymidine incorporation test.