Mystery to the origin of long-lived, skin-deep immune cells uncovered

Scientists at A*STAR’s Singapore Immunology Network (SIgN) uncovered the origin of a group of skin-deep immune cells that act as the first line of defence against harmful germs and skin infections. SIgN scientists discovered that these sentry cells of the skin, called the Langerhans cells (LCs), originate from two distinct embryonic sites - the early yolk sac and the foetal liver.

LCs are dendritic cells (DCs) found in the outermost layer of the skin. DCs are a critical component of the immune system because they are the only cells able to ‘see’ and ‘alert’ other responding to initiate a protective response against harmful foreign invaders. Like sentries of the immune system, DCs are strategically positioned where they are likely to encounter harmful pathogens. Identifying the source of these specialised immune cells may hold exciting possibilities to novel strategies for vaccination and treatment of autoimmune diseases and inflammatory skin disorders.

In contrast to other DCs which are constantly replaced by a circulating pool of bone marrow-derived precursors, LCs has the interesting ability to maintain themselves throughout life. While it is established that these long-lived sentry cells of the skin arise from precursors that are recruited to the skin prior to birth, this is the first time that the exact origin of the precursors of LCs is revealed through advanced fate-mapping technique (a method of tracing cell lineages to their embryonic origin).

In this study, published in the June issue of Journal of Experimental Medicine, Dr. Florent Ginhoux, and his team demonstrated that adult LCs originate from two distinct embryonic lineages in two succeeding waves. The first wave of precursor cells from the yolk sac ‘seed’ the skin before the onset of the foetal liver. Interestingly, the team discovered that at the later stage of development, the yolk-sac precursors are largely replaced by a type of white blood cells from the foetal liver.

Said Dr. Ginhoux, Principal Investigator of SIgN, “Whether this unique dual origin of Langerhans cells influences their ability to maintain skin integrity or dictate their specialised immune functions in response to microbes and vaccines needs to be examined. But having identified their origin surely opens new possibilities of using them as novel vaccination strategies or as therapeutic tool for treating inflammatory skin diseases like psoriasis.”

Scientific Director of SIgN, Professor Paola Castagnoli said, “This discovery sheds light on understanding the complexities of the immune system, in particular the relationship between immune responses and human diseases. It will bring us closer to our goal of discovering novel ways of treating and preventing a range of immune diseases that will impact healthcare.”

More information: The research findings described in this media release can be found in the 7 May online issue of The Journal of Experimental Medicine under the title, "Adult Langerhans cells derive predominantly from embryonic fetal liver monocytes with a minor contribution of yolk sac-derived macrophages” by Guillaume Hoeffel, et al. jem.rupress.org/content/early/… 20120340.short?rss=1

add to favorites email to friend print save as pdf

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 ...

Scientists discover origin of brain immune cells

Oct 27, 2010

A team of international scientists led by Dr Florent Ginhoux of the Singapore Immunology Network (SIgN) of Singapore's Agency of Science, Technology and Research (A*STAR), have made a breakthrough that could lead to a better ...

New path of origin for macrophages

May 02, 2012

Macrophages play a key role in the immune response, protecting organisms against infection and regulating the development of inflammation in tissue. Macrophages differ depending on where they are located and which tasks they ...

Scientists discover immune peacekeepers

Oct 17, 2011

There are more bacteria living on our skin and in our gut than cells in our body. We need them. But until now no-one knew how the immune system could tell that these bacteria are harmless.

Recommended for you

Food allergies more widespread among inner-city children

Aug 14, 2014

Already known for their higher-than-usual risk of asthma and environmental allergies, young inner-city children appear to suffer disproportionately from food allergies as well, according to results of a study led by scientists ...

New weapon of the immune system discovered

Aug 14, 2014

Max Planck researchers have discovered a completely new way in which the immune system recognizes pathogens. The aryl hydrocarbon receptor has long been a focus of research for pharma-cologists and toxicologists, ...

User comments