Superresolution single-molecule fluorescence microscopy has given researchers their clearest pictures yet of how white blood immune cells, known as natural killers, attack viral infections and tumors.
This fluorescence microscopy image shows natural killer cells (Pageon SV et al)
“The work could provide important clues for tackling disease,” said Prof Daniel Davis from the University of Manchester, who is a senior author of a paper reporting the results in the journal Science Signalling.
Until now, the limitations of light microscopy have prevented a clear understanding of how natural killer cells, which are responsible for fighting infections and cancer in the human body, detect other cells as being diseased or healthy.
The new images reveal how these cells change the organization of their surface molecules, when activated by a type of protein found on viral-infected or tumor cells. They show the proteins at the surface of immune cells are not evenly spaced but grouped in clusters – a bit like stars bunched together in galaxies.
“This is the first time scientists have looked at how these immune cells work at such a high resolution. The surprising thing was that these new pictures revealed that immune cell surfaces alter at this scale – the nanoscale – which could perhaps change their ability to be activated in a subsequent encounter with a diseased cell,” Prof Davis said.
“We have shown that immune cell proteins are not evenly distributed as once thought, but instead they are grouped in very small clumps – a bit like if you were an astronomer looking at clusters of stars in the Universe and you would notice that they were grouped in clusters.”
“We studied how these clusters or proteins change when the immune cells are switched on – to kill diseased cells. Looking at our cells in this much detail gives us a greater understanding about how the immune system works and could provide useful clues for developing drugs to target disease in the future.”
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Bibliographic information: Pageon SV et al. 2013. Superresolution Microscopy Reveals Nanometer-Scale Reorganization of Inhibitory Natural Killer Cell Receptors upon Activation of NKG2D. Sci. Signal., vol. 6, no. 285, p. ra62; doi: 10.1126/scisignal.2003947
