Patrolling our body, in search of diseased or foreign cells, is a crack squad of biological assassins known as natural killer (NK) cells. When they spot a sick cell, NK cells lock on, punch a hole and inject a payload of deadly enzyme-packed granules that kill within minutes. Using a new type of super-resolution microscope, and with laser ‘tweezers’ to manipulate the cells, researchers can now spy on the execution in greater detail than ever. Pictured is an NK cell (left) deciding whether its target cell (right) is dangerous. If deemed so, a ring-like tunnel will form (at the contact point dyed green) through which the toxic granules pass. NK cells play a prominent role in our immune system with duties that range from killing cancer cells to rejecting donor organs. In these scenarios, understanding the modus operandi of our natural killers is likely to aid development of new treatments.
BPoD stands for Biomedical Picture of the Day. Managed by the MRC London Institute of Medical Sciences the website aims to engage everyone, young and old, in the wonders of biomedicine. Images are kindly provided for inclusion on this website through the generosity of scientists across the globe.
BPoD is also available in Catalan at www.bpod.cat with translations by the University of Valencia.