Impairment of in vitro generation of monocyte-derived human dendritic cells by inactivated human immunodeficiency virus-1: Involvement of type I interferon produced from plasmacytoid dendritc cells

Abstract

In an attempt to simplify the protocol of DC generation in vitro, studies conducted herein show that functional DCs could be generated from bulk peripheral blood mononuclear cells (PBMCs) in media containing GM-CSF and IL-4. Interestingly, when PBMCs, but not purified monocytes, were exposed to either CCR5- or CXCR4-tropic inactivated HIV-1 isolates (iHIV-1) at the initiation of the culture, DC yields were significantly reduced in a dose-dependent manner because of monocyte apoptosis. Similar impairment of DC generation was noted using type I IFNs and poly IC not only in cultures of PBMCs but also using highly enriched monocytes. This effect was reversed by antihuman type I IFN receptor, but not by anti-FasL, anti-TRAIL, anti-TNF, or a mixture of these antibodies. iHIV-1-exposed PBMCs, but not monocytes, produced high levels of IFN-alpha but not IFN-beta. PBMCs depleted of CD123(+) plasmacytoid DCs produced low levels of IFN-alpha and were resistant to iHIV-1-mediated DC impairment. Interestingly, exogenously added TNF reversed the impairment by iHIV-1 in the PBMC cultures. In conclusion, the present results indicate that iHIV-1 impairs the in vitro generation of functional DCs from PBMCs through the induction of IFN-alpha from plasmacytoid DCs in a CD4-dependent fashion in the absence of TNF.