Langerhans cells and HIV infection

Langerhans cells are situated in epidermis of the skin and in all mucous membranes including oral, vaginal and cervical epithelium. Dendritic Langerhans-like cells are also present in lymphatics and draining lymph nodes. They are macrophage-like cells and play a major role in immunoregulation in these epithelia by presenting viral, bacterial, fungal and contact antigens to the T-lymphocytes, either in the epithelia, or after migration through lymphatic vessels, in the regional lymph node. There is a strong possibility that any antigen that enters the body through these epithelia will encounter Langerhans cells. ARC/AIDS patients have decreased numbers of epidermal Langerhans cells and HIV-producing Langerhans cells have been detected in the skin of these patients. The recent demonstration that HIV was able to infect Langerhans cells in vitro which after a few days in culture produced and released HIV able to infect cells from peripheral blood, indicate that Langerhans cells in the mucous membranes may be the primary target cells for HIV infection. They may then act as a Trojan horse in spreading the infection to other cells.