In a world first, scientists have managed to film a time-lapse video of the death of a white blood cell. What they’ve discovered is that in its final moments of life, it tries to warn the rest of the immune system to the presence of its killer.
Whilst looking at white blood cells – the cells of the immune system involved in protecting the body from potentially harmful intruders – a team of scientists from La Trobe University, Melbourne, used time-lapse microscopy to capture their deaths. This involved snapping hundreds of photos a second to capture every stage of the cell's death for the first time. They found that as the cell died, it produced what the scientists are calling “beads” that might be alerting the immune system to a pathogen. The study is published in the journal Nature Communications.
“So when the cell starts to die it forms these lumps which push outwards and when the cell then explodes, it shoots out long “beaded” protrusions which look like a necklace, which then breaks apart into individual 'beads,'” lead author Georgia Atkin-Smith told Australian Associated Press.
It was previously thought that during death, the white blood cells randomly fell apart. But to the contrary, the research has shown that the deterioration of the cells is highly regulated, and goes through three specific stages. Firstly, the cells bulge out, then they explode, and finally the left-over pieces break part. During this process, however, the dying cells eject these “beads-on-a-string structure” containing bits of the cell’s nucleus. The individual “beads” then shear off.
“After the cells bulge they go through this spectacular explosion where they push out large-beaded necklaces up to eight times the size of the cell,” explained Atkin-Smith. “The cells around them can easily engulf these smaller [individual bead] pieces. But we also think there are certain molecules in the beads that, when eaten by a live cell, can signal back a warning to other white blood cells to say, ‘Look out, there may be a pathogen coming to get you.'”
The researchers think that by hijacking these beads, viruses might be able to evade the immune system and spread throughout the body. They’ve also found that some drugs actually interfere with this process. “We found that a commonly used antidepressant can block this whole process and an antibiotic can promote this event,” explained Atkin-Smith. They hope that this knowledge might help in developing novel techniques to fight disease.