Natural (born) killers: What do they really do?

Feb 22, 2011

Our immune systems contain three fundamentally different types of cell: B-cells, T-cells and the mysteriously named Natural Killer cells (NK cells), which are known to be involved in killing tumour cells and other infected cells. Experiments to investigate the function of NK cells have proven difficult to interpret because the interactions between the various components of the immune system make it almost impossible to isolate effects of individual cell types. This has changed with the development of a mouse in which individual genes can be knocked out (eliminated) only in NK cells, thereby providing scientists with a tool to study the importance of NK cells and indeed of individual pathways in these cells. The mouse was generated in the group of Veronika Sexl, who has recently moved from the Medical University of Vienna to the University of Veterinary Medicine, Vienna. An initial characterization is presented in the current issue of the journal Blood.

The development of a tool alone would not normally generate headlines but this case is different: the new mouse can be used to knock out any gene completely and exclusively in NK cells. It thus permits researchers to examine the functions of NK cells in the entire organism or even to investigate the importance of individual in this particular cell-type.

Sexl herself has naturally used the tool already. She has been able to show that a particular transcription factor known as Stat5 is essential for the correct development of NK cells – when this factor is eliminated, the cells fail to develop properly. The upshot is a mouse with an that lacks NK cells but is otherwise fully intact. This is the first time it has proven possible to remove this particular cell type without affecting the rest of the animal. Finally, then, it is possible to learn what NK cells actually do in the intact organism.

Sexl and her collaborators have shown that mice lacking NK cells have normal T-cell responses to tumours, although their NK cell-mediated responses are naturally dramatically reduced. This experiment proves conclusively that the mouse can be used to untangle the web of interactions among the various cells of the immune system.

Sexl's work has immediate implications for the treatment of cancer in humans. As an example, leukemia is sometimes treated by inhibiting the STAT5 protein. Sexl's findings make it clear that this approach has a real drawback: inhibition of STAT5 will lead to a drop in the number of NK cells and so interfere with one of the body's own mechanisms for fighting the cancer. It will be important to assess whether normally play a part in fighting diseases before inhibiting STAT5. For the first time, the newly developed mouse provides a tool to do so. Not surprisingly, it is already attracting a great deal of interest – as Sexl says, "They've been going like hot cakes ever since the word got out."

Explore further: US scientists make embryonic stem cells from adult skin

Provided by University of Veterinary Medicine -- Vienna

not rated yet
add to favorites email to friend print save as pdf

Related Stories

New role for natural killers

Aug 27, 2008

Scientists at the University of York have discovered a new role for a population of white blood cells, which may lead to improved treatments for chronic infections and cancer.

'Natural killer' cells keep immune system in balance

Oct 01, 2009

Natural killer, or NK cells, are part of our innate immune system. A healthy body produces them to respond early during infection. They are activated and they kill cells infected with a given virus.

Immune system important in fight against stomach cancer

Jun 28, 2010

Researchers have identified cells in the immune system that react to the stomach ulcer bacterium Helicobacter pylori, one of the risk factors for the development of stomach cancer. This discovery could lead to faster diagno ...

Recommended for you

Leeches help save woman's ear after pit bull mauling

Apr 18, 2014

(HealthDay)—A pit bull attack in July 2013 left a 19-year-old woman with her left ear ripped from her head, leaving an open wound. After preserving the ear, the surgical team started with a reconnection ...

New pain relief targets discovered

Apr 17, 2014

Scientists have identified new pain relief targets that could be used to provide relief from chemotherapy-induced pain. BBSRC-funded researchers at King's College London made the discovery when researching ...

User comments : 0

More news stories

Filipino tests negative for Middle East virus

A Filipino nurse who tested positive for the Middle East virus has been found free of infection in a subsequent examination after he returned home, Philippine health officials said Saturday.

Study says we're over the hill at 24

(Medical Xpress)—It's a hard pill to swallow, but if you're over 24 years of age you've already reached your peak in terms of your cognitive motor performance, according to a new Simon Fraser University study.

NASA's space station Robonaut finally getting legs

Robonaut, the first out-of-this-world humanoid, is finally getting its space legs. For three years, Robonaut has had to manage from the waist up. This new pair of legs means the experimental robot—now stuck ...

Ex-Apple chief plans mobile phone for India

Former Apple chief executive John Sculley, whose marketing skills helped bring the personal computer to desktops worldwide, says he plans to launch a mobile phone in India to exploit its still largely untapped ...

Egypt archaeologists find ancient writer's tomb

Egypt's minister of antiquities says a team of Spanish archaeologists has discovered two tombs in the southern part of the country, one of them belonging to a writer and containing a trove of artifacts including reed pens ...

Airbnb rental site raises $450 mn

Online lodging listings website Airbnb inked a $450 million funding deal with investors led by TPG, a source close to the matter said Friday.