NK cells under the microscope
3 Oct 2011 by Evoluted New Media
Optical tweezers and a super resolution microscope have revealed the inner workings of white blood cells at the highest resolution ever.
Researchers from Imperial College London and the University of Oxford discovered that white blood cells called Natural Killer (NK) cells rearrange their scaffolding of actin proteins on the inside of its membrane to create a hole through which it delivers deadly enzyme-filled granules to kill diseased tissues.
“These previously undetectable events inside cells have never been seen in such high resolution,” said Dr Alice Brown from Imperial. “It is truly exciting to observe what happens when an NK cell springs into action.”
NK cells protect the body by identifying and killing diseased tissue, but how they did this was hampered by a lack of technology to view them – this new technique allows the ‘how’ to be revealed. Researchers immobilised an NK cell and its target using optical laser tweezers so that a super-resolution microscope could capture what was happening between the cells.
The dense mesh of actin which underlies the immune synapse is remodelled upon NK cell activation. Domains open up specifically where lytic granules dock, the enzyme-filled granules then move out of this portal and towards the target.
“This has provided an unprecedented means to directly see dynamic molecular processes that go on in between live cells,” said Professor Paul French who developed the microscopy technique.
The work – published in PLOS Biology – may lead to better healthcare for some patients, particularly those undergoing tissue transplants.
“NK cells are important in our immune response to viruses and rogue tissues like tumours,” said Professor Daniel Davis, who led the research. “They may also play a role in the outcome of bone marrow transplants by determining whether a recipient’s body rejects or accepts the donated tissue.”
The hope is that drugs which influence where and when NK cells kill could be included in medical treatments, such as the targeted killing of tumours. They may also prevent transplant rejections and some autoimmune disease, said Davis.
