The role of skin dendritic cells in the initiation of human immunodeficiency virus infection.

Human immunodeficiency virus (HIV) can be transmitted by accidental puncture with needles containing HIV-contaminated blood. However, the molecular and cellular interactions that occur between HIV and cells of the skin following percutaneous needlestick injury are unknown. Direct inoculation of exogenous virus into recipient blood vessels of the dermis is possible. In addition, skin dendritic cells (DC; e.g., epidermal Langerhans cells, dermal DC, lymphatic veiled cells) may also play a role in the initiation of HIV infection. Evidence to suggest that DC are important in primary HIV infection is derived largely from in vitro experiments and animal models. For example, cutaneous DC can be infected with HIV in vitro, can capture HIV on their cell surface (independent from DC infection), and can efficiently transmit HIV to CD4+ T cells. In recent in vivo experiments using rhesus macaques, submucosal DC were the first cells infected following intravaginal exposure to simian immunodeficiency virus (SIV). In this review, I discuss the possible immunologic events that occur within skin and draining lymph nodes following needlestick exposure to HIV-contaminated blood, with a particular emphasis on DC-HIV interactions.