Langerhans cell

Langerhans' cells are dendritic cells abundant in epidermis, containing large granules called Birbeck granules. They are normally present in lymph nodes, and can be found in other organs in the condition Histiocytosis.

Named after German anatomist and physician Paul Langerhans (1847-1888) who described it in skin while a medical student.

Function
On infection of an area of skin, the local Langerhans' cells will take up and process microbial antigens to become fully-functional antigen-presenting cells.

Generally, dendritic cells in tissue are active in the capture, uptake and processing of antigens. Once dendritic cells arrive in secondary lymphoid tissue however, they lose these properties while gaining the capacity to interact with naive T-cells.

Langerhans' cells are derived from the cellular differentiation of monocytes with the marker "Gr-1" (also known as "Ly-6c/G"). The differentiation requires stimulation by colony stimulating factor-1. They are similar in morphology and function to macrophages.

LCH
In the rare disease Langerhans' cell histiocytosis (LCH), an excess of these cells is produced, which can cause damage to skin, bone and other organs.

HIV
Langerhans' cells capture HIV-1 virions by way of Fc receptor binding to antibody-coated virus. Langerhans' cells act as reservoirs for the HIV-1 virus, serving as a site of replication when T-cells become depleted (Robbins Pathology).

Langerhans' cells have been observed in foreskin, vaginal, and oral mucosa of humans; the lower concentrations in oral mucosa suggest that it is not a likely source of HIV infection relative to foreskin and vaginal mucosa.

On March 4, 2007 the online Nature Medicine magazine published the letter "Langerin is a natural barrier to HIV-1 transmission by Langerhans cells", written by Dutch scientists which claims "that Langerin is able to scavenge viruses from the surrounding environment, thereby preventing infection", as lead researcher Teunis Geijtenbeek of Vrije University Medical Center in Amsterdam told to YahooNews-HealthDay reporter.