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 Cells communicate in a dynamic code
19.02.2018 | California Institute of Technology

nachricht Studying mitosis' structure to understand the inside of cancer cells
19.02.2018 | Biophysical Society

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

Im Focus: Interference as a new method for cooling quantum devices

Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters

Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Contacting the molecular world through graphene nanoribbons

19.02.2018 | Materials Sciences

When Proteins Shake Hands

19.02.2018 | Materials Sciences

Cells communicate in a dynamic code

19.02.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>