Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Newly discovered killer cell fights cancer

07.03.2006


A mouse immune cell that plays dual roles as both assassin and messenger, normally the job of two separate cells, has been discovered by an international team of researchers from the United States and France. The discovery has triggered a race among scientists to find a human equivalent of the multitasking cell, which could one day be a target for therapies that seek out and destroy cancer.



"In the same way that intelligence and law enforcement agencies can face deadly threats together instead of separately, this one cell combines the ability to kill foreign pathogens and distribute information about that experience," says Drew Pardoll, M.D., Ph.D., the Seraph Professor of Oncology at the Johns Hopkins Kimmel Cancer Center.

"We think this hybrid cell speeds up immune reactions and makes the system more efficient," adds Pardoll, whose findings are reported in the February issue of Nature Medicine.


The Hopkins investigators speculate that the hybrid, dubbed "IKDC" for interferon-producing killer dendritic cell, has been missed by cancer biologists because it is rare, making up one-tenth of cells in the spleen with similar features, such as other dendritic cells, according to Frank Housseau, Ph.D., research associate at Hopkins’ Kimmel Cancer Center and member of Pardoll’s immunology laboratory.

Most of the immune system typically works through a web of cross-talk and signaling among a variety of cells. One of the first immune cells that invading bacteria or cancer cells - both of which carry antigens that alert the immune system - may encounter is a natural killer (NK) cell. As its name implies, NK cells deliver a deadly blow by poking holes in the invader’s outer membrane. Then, NK cells secrete molecules that reach other immune cells, including dendritic cells, known as the main messenger for the immune system. Dendritic cells spread "look here" information about foreign invaders to other immune cells, but do not actually kill the invaders.

It was while investigating a particular type of dendritic cell that Housseau noticed the outer membranes of these cells were studded with what were supposed to be hallmarks of NK cells, akin to finding feathers on a dog.

"We thought we were looking at dendritic cells, but we were wrong - they were some type of NK-dendritic cell blend," says Housseau. The blended cell turned out to be a newly identified actor on the immune system stage that retains all the molecular characteristics of both NK and dendritic cells.

Probing further, Housseau scoured the surface of IKDCs to create a sketch of its molecular profile. He found that it produces both types of interferon proteins, normally secreted independently by NK and dendritic cells. He also found both NK and dendriticlike molecules on the surface of IKDCs. Housseau calculated that they account for about 10 percent of conventional dendritic cells in the spleen.

IKDCs begin their lives behaving like an NK cell. After the cell encounters a pathogen, the cell switches roles from killer to dendriticlike messenger, and, according to the researchers, the swap occurs only once. Then, the cell dies and is replenished by the bone marrow.

"When an IKDC cell switches to its messenger function, the transformation is quite astonishing," says Pardoll. The cell sprouts long, hairy tentacles called dendrites. It uses its "arms" to increase the amount of surface area it reaches to communicate and interact with other immune cells.

In the next step of their investigation, the scientists tracked the location of fluorescent-tagged IKDCs and their corresponding stage of transformation after infecting mice with bacteria called listeria. In assassin-mode, the IKDCs were found in the blood, lining of the gut, liver and other organs - all areas where there is close contact with environmental pathogens. "Here, IKDCs are ready to sense invaders and spring into action," says Housseau.

Then, the group tracked the cells to the main messenger center of the immune system - the lymph nodes. Here, they found approximately 35 percent of the original group of IKDCs now secreting communication molecules signaling a switch to messenger-mode.

Simultaneously, Housseau’s colleagues in France, led by Laurence Zitvogel at the Institut Gustave Roussy, tested whether IKDCs are culprits in killing cancer by injecting mice with a cancer drug called Gleevec, which blocks an abnormal protein produced by cancer cells, and a growth factor for NK cells. The drug-growth factor combo served as a lure, leading the IKDCs to tumors implanted in the mice. The results were that tumors shrunk in mice, which received injections of IKDCs, but not in those receiving conventional NK cells only. Evidence from the shrunken tumors revealed certain "cell-killing" proteins that could be traced to IKDCs. These results are published separately in Nature Medicine.

Housseau’s group is conducting further studies to verify the role of IKDC cells in infection and cancer. Meanwhile, the group is profiling IKDC genes to find a specific marker that could help them identify a human counterpart.

Vanessa Wasta | EurekAlert!
Further information:
http://www.hopkinskimmelcancercenter.org
http://www.jhmi.edu

More articles from Life Sciences:

nachricht How brains surrender to sleep
23.06.2017 | IMP - Forschungsinstitut für Molekulare Pathologie GmbH

nachricht A new technique isolates neuronal activity during memory consolidation
22.06.2017 | Spanish National Research Council (CSIC)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>