Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Rac 1 and 2, two proteins essential to triggering of the immune response

23.08.2004


When a dendritic cell meets a T cell… The dendritic cell and its “arms” can be seen on the left of the images. On the right is a smaller T cell. In the first image, the dendritic cell reaches out in search of a T cell. In the second image, it finds a T cell and extends its arms towards it. In the third image, the dendritic cell entraps the T cell. © F. Benvenuti/Institut Curie


In this dendritic cell, the proteins Rac 1 and 2 are inactive. The dendritic cell is "unaware" of the presence of the T cell. © F. Benvenuti/Institut Curie


The dendritic cells act as the body’s sentries, standing guard around the clock. As soon as they detect a potential enemy, they alert the T cells, whose role is to defend the body.

At the Institut Curie, CNRS researchers in an Inserm laboratory have filmed the encounter of dendritic cells and T cells. They have shown that this "rendez-vous", which is indispensable for the activation of the immune system, cannot take place in the absence of the proteins Rac 1 and 2. Published in the August 20, 2004 issue of Science, this discovery yields new information on the immune system and could in time pave the way for advances in immunotherapy.

Our immune system is on call round the clock. Whenever a foreign body intrudes (virus, bacterium…), or even in response to the anarchic proliferation of the body’s own cells (cancer), the immune system sounds the alarm.



Dendritic cells are the "sentries" responsible for detecting the presence of an intruder in our body. When they locate a potentially dangerous cell, they partially ingest it and isolate a characteristic fragment, an antigen(1). Bearing this fragment they then migrate to the lymph nodes, where the T cells are to be found. The dendritic cells present the antigen to T cells, thus enabling them to recognize the enemy, which they must eliminate. Once informed, T cells launch a targeted offensive to rid the body of bacteria, tumor cells or virus-infected cells. At the Institut Curie, Sebastian Amigorena(2) and his team are studying how the body’s sentries identify the antigen and then present it to the T cells.

The dendritic cell stretches out its arms…

To observe the in vivo meeting between dendritic cells and T cells in the lymph nodes, Sebastian Amigorena and colleagues, in partnership with Luc Fetler(3), have used the highly sophisticated technique of two-photon microscopy (see box). This is the first time in Europe that two-photon microscopy has been utilized to follow the triggering of immune responses in vivo, in intact organs.

Rather like starfish, dendritic cells have several "arms", formed by membrane extensions. Once they reach the lymph nodes, the dendritic cells stretch out these arms in their search for T cells(4).

…and entraps the T cell

When a T cell is found, the dendritic cell’s arms stretch towards it by extension of the cell membrane and "engulf" it. The Institut Curie scientists noted that this "engulfment", which is essential to effective triggering of an immune response, cannot occur without the presence of proteins Rac 1 and 2(5). These two proteins control the extension of the dendritic cell membrane when the T cell is contacted. When Rac 1 and 2 are inactivated, the meeting between the T cells and the dendritic cells does not happen and as a result the immune response is not triggered.

This discovery should lead to optimization of one of the promising approaches to cancer treatment – immunotherapy, in which the immune system is used to destroy tumor cells. By measuring the expression and activation state of Rac 1 and 2, it may be possible to assess, and if necessary enhance, the efficacy of dendritic cells in initiating the immune response.

Catherine Goupillon | alfa

More articles from Life Sciences:

nachricht Nanoparticle Exposure Can Awaken Dormant Viruses in the Lungs
16.01.2017 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt

nachricht Cholera bacteria infect more effectively with a simple twist of shape
13.01.2017 | Princeton University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

Im Focus: Bacterial Pac Man molecule snaps at sugar

Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.

The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

Water - as the underlying driver of the Earth’s carbon cycle

17.01.2017 | Earth Sciences

Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

17.01.2017 | Materials Sciences

Smart homes will “LISTEN” to your voice

17.01.2017 | Architecture and Construction

VideoLinks
B2B-VideoLinks
More VideoLinks >>>