The only way to protect against these afflictions is to destroy all immune factors that turn against the body’s own tissue – in other words: immune tolerance.
A team working with LMU researcher Dr. David Vöhringer has now investigated exactly what role dendritic cells play in this process. There has long been suspicion that these cells, which are important for the body’s defenses, are also essential for the establishment and maintenance of immune tolerance.
“We investigated mice that lacked this cell type from birth,” reports Vöhringer. “It turned out that immune cells that attack the body’s own tissue survive in these animals, and thereby trigger an autoimmune response. It follows that dendritic cells play a major part in protecting against autoimmune disease.”
T cells are a type of white blood cell that are key actors in the body's immune defenses. Each T cell has a receptor on its surface for recognizing just one single antigen. Antigens are molecular structures, mostly fragments of proteins. T cells do not dock onto free antigens, however: they rely on other cells which can present antigens to them. It is the dendritic cells that are primarily responsible for this job. They present the T cells with various antigens, and if an antigen matches a receptor, then that T cell will trigger an immune response from the body.
This is how the body defends itself against pathogens and other intruders. But behind this tactic lies an element of danger to the organism: what happens if the antigen is not foreign, but originates from the body’s own tissue instead? A wrongly induced immune response can lead to a severe autoimmune disease that, if left untreated, could lead to destruction of organs or even death. So-called autoreactive T cells, which recognize the body’s own structures, must be eradicated or pacified to avoid that they can cause harm. A T cell screening process therefore takes place in the thymus, the bilobular organ in the upper thorax, to distinguish the good from the bad of these dangerous lone mavericks. Each individual T cell is tested, and the autoreactive ones destroyed.
The remaining T cells are checked a second time in the peripheral lymphatic organs of the body. This constant quality control goes on mostly in the lymph nodes and the spleen. As has been known for a while now, dendritic cells can induce peripheral tolerance although it remained unclear whether they are essential for this process. Dendritic cells migrate continuously out of tissues and organs into the lymph nodes, bringing tissue material with them and present it to T cells. Any T cell that reacts to the body’s own proteins is then deactivated or killed off.
Most recent findings have shown that dendritic cells are essential to generate and maintain immunological tolerance. “Our work on mice has proven that without dendritic cells, even the first, central screening of autoreactive T cells in the thymus runs only at reduced efficiency,” reports Vöhringer. “In these animals, the thymus releases T cells that react to the body’s own material. These are then activated in the peripheral organs – and trigger autoimmunity.”
In light of the crucial role these cells play, it is a logical question as to how autoimmunity can be triggered at all without dendritic cells. After all, it is the dendritic cells that undertake certain critical tasks during an immune response. “Among other things, they are specialized in presenting antigens to T cells, which is what makes an immune response at all possible in the first place,” says Vöhringer. “So we are left with the question as to what type of cell activates the autoreactive T cells if the supposedly most important antigen-presenting cells – the dendritic cells – are missing. We already have a few candidates for this, and are studying their function more closely now.” (suwe)Publication:
Further reports about: > Antigens > LMU > T cells > autoimmune disease > autoreactive T cells > dendritic > dendritic cells > diabetes mellitus type 1 > immune cell > immune response > immune tolerance > lymph node > molecular structure > molecular structures > multiple sclerosis > peripheral organs > proteins
Atomic-level motion may drive bacteria's ability to evade immune system defenses
24.04.2017 | Indiana University
Two-dimensional melting of hard spheres experimentally unravelled after 60 years
24.04.2017 | University of Oxford
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
24.04.2017 | Physics and Astronomy
24.04.2017 | Materials Sciences
24.04.2017 | Life Sciences