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Wellcome Image Awards 2015 A Killer Instinct
01 April 2015

A Killer Instinct

Protecting us from viruses, bacteria and other enemies requires a diverse skill set, and the immune system employs a number of different cell types to achieve this. Those responsible for the most rapid response are known as 'natural killer', or NK, cells, as they can detect diseased cells without having to recognise a specific marker of the agent causing the problem. Here, an NK cell (on the left) has come into contact with another cell, and is checking it for signs of viral infection or other stresses. If it spots an anomaly, it will release toxic molecules (in red) from specialised compartments, the cytotoxic granules; these will trigger apoptosis, the self-destruction of the target cell and any virus particles it contains. All this requires substantial rearrangements of the NK cell, both at its surface and within, and much remains to be learned about this critical process in our immune defences.

Written by Emmanuelle Briolat

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