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


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 Novel mechanisms of action discovered for the skin cancer medication Imiquimod
21.10.2016 | Technische Universität München

nachricht Second research flight into zero gravity
21.10.2016 | Universität Zürich

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>