Dendritic cells and HIV specific CD4(+) T cells: HIV antigen presentation, T-cell activation, and viral transfer

Groupe Virus et Immunité, Unité de Recherche Associée (URA) Centre National de la Recherche Scientifique (CNRS) 1930, Paris, France.
Blood (Impact Factor: 9.78). 10/2006; 108(5):1643-51. DOI: 10.1182/blood-2006-02-006361
Source: PubMed

ABSTRACT Human immunodeficiency virus (HIV)-specific CD4+ lymphocytes are preferentially infected in HIV-positive individuals. To study this preferential infection, we have derived several HIV-specific (HS) CD4+ clones. We show that in dendritic cells (DCs), HIV virion capture led to major histocompatibility complex class-II (MHC-II)-restricted viral antigen presentation and to activation of HS cells. In contrast, neither cell-free virions nor infected lymphocytes activated HS cells. In DCs, the dendritic cell-specific intercellular adhesion molecule 3-grabbing nonintegrin (DC-SIGN/CD209), which internalizes virions, promoted MHC-II presentation of HIV antigens. Activation of HS cells by HIV-exposed DCs triggered an efficient viral spread in lymphocytes. CD4+ clones with irrelevant antigenic specificities were not activated by HIV-exposed DCs and poorly supported viral replication under this setting. Our results unravel the mechanisms of MHC-II-restricted HIV antigen presentation by DCs and describe how HIV gains access to the very cells designed by the immune system to counteract this pathogen.

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