Mucosal dendritic cells and immunodeficiency viruses.

Dendritic cells [DCs] have been implicated in the pathogenesis of human immunodeficiency virus type 1 (HIV-1). When skin was used as a model for mucosae, the cutaneous DC-T cell milieu allowed the growth of HIV-1 and much of the newly produced virus could be detected in multinucleated DC-T cell syncytia. Such virus replication occurs irrespective of the genetic subtype, the syncytium- and non-syncytium-inducing capacities of the viruses, and whether they are classified as T cell- or macrophage-tropic. Similar DC-syncytia have been identified within the mucosal surfaces of the tonsillar tissue of HIV-1-infected persons. More recently, it was demonstrated that DC-T cell mixtures from the skin, mucosae, and blood of healthy macaques similarly support the replication of simian immunodeficiency virus. In both the human and monkey systems, active virus replication requires the presence of both DCs and T cells. Further studies using the macaque model are underway to elucidate the role of DCs in the transmission and spread of HIV infection.