How Langerhans Cells Protect You From Harm

Langerhans cells (LCs) are located in the skin (the epidermis and the dermis) of the respiratory, digestive, and urogenital tracts. They can also be found in other tissues such as lymph nodes, particularly when the condition Langerhans cell histiocytosis (LCH) is involved.

LCs, help to protect you by keeping dangerous antigens (any substance that causes the immune system to produce antibodies against it) from entering your body.

How Langerhans Cells Work

Discovered by a 21-year-old German medical student, Paul Langerhans, in 1868, Langerhans cells are present in all layers of the epidermis and are members of the dendritic family. Dendritic cells are immune cells that present antigens to the immune system and are found all throughout the body. LCs are dendritic cells in the skin and since dendritic cells are extremely efficient at alerting the immune system to the presence of pathogens and other foreign materials, the skin is an important barrier to infection.

LCs were originally thought to be a part of the nervous system and only alert the immune system to antigens. Instead, research has found that LC's dampen the skin's reaction to infection and inflammation in 2 very different ways:

• By protecting your skin from infection.
• By stimulating allergic reactions.

Langerhans cells send out special agents — immune cells such as T cells and B cells — immediately after sensing any kind of danger in the skin. The immune cells capture trespassers such as bacteria and viruses and fight off injuries like cuts and scrapes.

The environment of the skin is constantly monitored by LCs for unsafe situations and the immune cells are sent to bring back information about any foreign invaders. The body then amasses a great force of inflammatory cells to fight off invaders by creating an allergic reaction or forming scar tissue to protect from infection.

LCs and Skin Conditions

Research suggests that Langerhans cells are able to identify and attack viruses from the surrounding environment, thereby preventing infection. This finding that LCs are involved in immune responses against various diseases could make them potential targets for immunotherapy.

This finding also has the potential to significantly change the understanding of the mechanisms underlying many skin disorders such as:

• Psoriasis: A condition in which skin cells build up and form scales accompanied by some redness, itchiness and dry patches.
• Lupus: An inflammatory disease caused when the immune system attacks its own tissues.
• Skin Cancer: The most common form of cancer in the US, characterized by the abnormal growth of skin cells.

There may also be the development of topical vaccines administered through the skin (Epicutaneous immunization) that focus on loading LCs directly into the skin with antigens. Research is already looking at vaccines given through barrier-disrupted skin in order to inhibit the growth of melanoma, a serious type of skin cancer.

What Is Langerhans Cell Histiocytosis (LCH)?

Langerhans cell histiocytosis (LCH) is a group of rare, idiopathic disorders which can cause damage to the skin, bones and other organs. An overload of cells similar to LCs are produced in this disorder, however, LCH cells show a different, hematopoietic (blood cells) origin for the disorder.