Double duty: Versatile immune cells play dual roles in human skin

A new study helps to resolve an ongoing controversy about whether Langerhans cells (LCs) in human skin function to suppress the immune response and promote tolerance to normal human skin and its "friendly" microbial flora or mobilize a lethal attack against harmful foreign invaders. The research, published online May 3rd in the journal Immunity by Cell Press, reveals that, depending on the situation, these versatile immune cells can perform either function.

Adult contains billions of resident called T that provide protection from invading pathogens. Skin also contains LCs, which reside in the outermost layer of skin, the epidermis. LCs are known to interact with T cells and are traditionally considered to be the first line of defense against invading pathogens. However, previous studies have provided conflicting results about the specific function of LCs. Also, until now, it has been difficult to characterize the role of LCs in human skin, primarily because much of the research has been done using mouse models and there appear to be significant differences between LCs in mouse and human skin.

"There is substantial controversy surrounding the role of LCs with regards to whether they serve to stimulate the upon encountering an invading pathogen or whether they play a more immunomodulatory role and induce tolerance in normal skin," explains senior study author, Dr. Thomas S. Kupper from Brigham and Women's Hospital and the Harvard Skin Disease Research Center. Taking advantage of a significant technical advance in the ability extract large numbers of specific immune cells from human skin, Dr. Kupper and colleagues examined the function of LCs under normal conditions and in the presence of a pathogen.

Interestingly, the researchers found that LCs interact with two different types of skin resident T cells. Under normal conditions, LCs induced proliferation of "regulatory" T cells that helped to prevent the immune system from attacking normal skin. In the presence of a pathogen, the LCs stimulated another type of T cell that mediates protective immunity. "Essentially, this means that LCs can apply the brakes to the immune response and maintain tolerance under normal conditions, but also have the capacity to push the gas and activate protective skin-resident T cells to mount an immune response when confronted with potentially harmful invaders," concludes Dr. Kupper. "This context-specific response is perfectly suited to a cell like the LC which is at the interface of the body and the environment."

Related Stories

Skin sentry cells promote distinct immune responses

Jul 21, 2011

A new study reveals that just as different soldiers in the field have different jobs, subsets of a type of immune cell that polices the barriers of the body can promote unique and opposite immune responses against the same ...

Gatekeeper signal controls skin inflammation

Jan 26, 2012

A new study unravels key signals that regulate protective and sometimes pathological inflammation of the skin. The research, published online on January 26th in the journal Immunity by Cell Press, identifies a "gatekeeper" that, ...

Stress may make you itch

Oct 27, 2008

Current research suggests that stress may activate immune cells in your skin, resulting in inflammatory skin disease. The related report by Joachim et al., "Stress-induced Neurogenic Inflammation in Murine Skin Skews Dendritic ...

Recommended for you

Leeches help save woman's ear after pit bull mauling

Apr 18, 2014

(HealthDay)—A pit bull attack in July 2013 left a 19-year-old woman with her left ear ripped from her head, leaving an open wound. After preserving the ear, the surgical team started with a reconnection ...

New pain relief targets discovered

Apr 17, 2014

Scientists have identified new pain relief targets that could be used to provide relief from chemotherapy-induced pain. BBSRC-funded researchers at King's College London made the discovery when researching ...

User comments