For the first time ever, molecular biologists have filmed the death of a human white blood cell. But the video shows something else, too. These integral components of our immune system do not go quietly into that good night. Rather, they go down alerting their neighbors to the presence of potential pathogens.
Scientists from the La Trobe Institute of Molecular Science watched as certain molecules were ejected from inside the decomposing cell to form long beaded strings. These beads, which are up to eight times stronger than the host cell itself, eventually broke off and disseminated through the body. The details of this work, led by researchers Ivan Poon and Georgia Atkin-Smith, can be found in the latest issue of Nature Communications.
The cell was observed to go through three different stages as it died: bulging, exploding, and then breaking apart.
“The role of white blood cells is central to our body’s innate immune system and much like fighter jet pilots are ejected from their downed aeroplane, we have discovered certain molecules are pushed free from the dying cell, while others are left behind in the ‘wreckage’ of the cell fragments,” noted Poon in a statement. “It is the first time we have ever seen this take place and we now need to better understand the reasons behind this and the implications of this process of cell fragmentation.”
The strings, dubbed “beaded apoptopodia”, are comprised of proteins implicated in signal transfer, cellular growth, and maintenance. The researchers theorize that some molecules within the beads contain a chemical warning that relays a message to other white blood cells that a pathogen, like a virus or infection, is in the vicinity.
Read the entire study at Nature Communications: “A novel mechanism of generating extracellular vesicles during apoptosis via a beads-on-a-string membrane structure”.