NK cell ensnaring a target cell Credit: Imperial College London
Immune cells ensnare dangerous cells that are on the run with a bungee-like nanotube, according to research published today in the Proceedings of the National Academy of Sciences. The study, by researchers from Imperial College London, shows that natural killer (NK) cells use this bungee to destroy cells that could otherwise escape them.
NK cells are our first line of defence against dangerous cells, such as tumour cells and cells infected with bacteria and viruses. Researchers are keen to understand how NK cells work because they help the body to fight infection and stop tumours from growing. It is thought that it may ultimately be possible to design drugs that harness the cells' ability to fight disease.
Prior to today's study, it was already known that NK cells can kill their target cells by attaching onto them, forming a connection called an immune synapse, which they use to pass toxic molecules into their target. However, sometimes the target cells move away from the NK cells to escape being killed.
Credit: Imperial College London/PNAS
Professor Daniel Davis, corresponding author of the study from the Division of Cell & Molecular Biology at Imperial College London said: "Natural Killer cells are cells that are really good at killing tumours and virus-infected cells. It was thought they kill these diseased cells only by sticking to them tightly for several minutes. These new movies show that in fact they also tether cells with long membrane connections and can pull diseased cells back into contact. We think they may also use these nanotubes to kill them from a distance.
"The movies show the process vividly but the next step is difficult because we have to know where and when these processes are important in your body, and the technology to see such thin nanotubes in the body hasn't been invented yet! It's a very new research area and we need to learn how the process works precisely so that we can then think about ways to design drugs that help immune cells kill," added Professor Davis.
Their next step will be to find out exactly how the bungee tubes help immune cells kill their target cells. The researchers hope that a better understanding of the process may help others in the future to develop drugs to improve the function of NK cells.
The researchers looked at the membrane nanotubes by staining cells with a dye that reveals membranes in microscope images. They found membrane nanotubes connecting NK cells with other NK cells, tumour cells, cells infected with viruses and cancer cells.
The researchers took video footage of the cells, showing the target cells moving away and being pulled back towards the NK cells. When a target cell moves away from an NK cell, it normally moves 'head' first, at around eight micrometres per minute. However, today's research shows that when the NK cell pulls its target cell back using the nanotube bungee it moves much faster, at around 14 micrometres per minute, and the cell is pulled backwards.
Membrane nanotubes increase an NK cell's chance of killing its target cell from a distance dramatically. In today's study, NK cells killed their target cells from a distance in 12 out of 16 cases (75 per cent) if they were connected by a membrane nanotube, compared to four out of 18 (25 per cent) if the nanotube was cut.
###
Imperial College London: http://www.imperial.ac.uk/press Thanks to Imperial College London for this article.
This article has been viewed 280 time(s).
 |
 Digg |
 FarkIt |
 |
 StumbleUpon |
 del.icio.us |
 |
In 1824, three years before he began to publish his famous "double elephant folio" The Birds of America, John James Audubon (1785-1851), the eminent artist of American birds and animals, created a drawing of a running grouse for use in the design for a New Jersey bank note.
The recent discovery of more than a thousand genes known as large intergenic non-coding RNAs (or "lincRNAs") opened up a new approach to understanding the function and organization of the genome. That surprising breakthrough is now made even more compelling with the finding that dozens of these lincRNAs are induced by p53, the most commonly mutated gene in cancer
A genetics research team based at The Children's Hospital of Philadelphia continues to discover recurrent translocations—places in which two chromosomes exchange pieces of themselves. As many as 1 in 600 persons carry balanced chromosome translocations, which involve no loss or gain of DNA.
Some trees growing in nutrient-poor forest soil may get what they need by cultivating specific root microbes to create compounds they require. These microbes are exceptionally efficient at turning inorganic minerals into nutrients that the trees can use. Researchers from France report their findings in the July 2010 issue of the journal Applied and Environmental Microbiology.
"Macho, macho man. I've got to be, a macho man. Macho, macho man. I've got to be a macho!" — The Village People
"If one finds something once, it's accidental. If it is found twice, it's puzzling. If found thrice, there is a pattern," the archaeologists Olle Hemdorff and Eva Thäte say.
"In laboratory tests, right- and left-handers associate positive ideas like honesty and intelligence with their dominant side of space and negative ideas with their non-dominant side," says Daniel Casasanto of the Max Planck Institute for Psycholinguistics in Nijmegen, Netherlands.
Often causing no symptoms in carriers of the disease, worldwide tuberculosis (TB) infects eight to ten million people every year, kills two million, and it is highly contagious as it is spread through coughing and sneezing.