An Orderly Swarm

The immune system prowls the body looking for a fight. When its abundant foot soldiers, neutrophils, encounter a threat they attack the invading microbe and call for backup, which arrives in large numbers, each reinforcement also calling for more. This swarm of support mounts an effective defence, but left unchecked could cause collateral damage, like superheroes wrecking buildings while defeating villains. A new study has visualised the process in mice (pictured, falsely coloured neutrophils forming a red cluster over time) and revealed that the swarming neutrophils become insensitive to their own secreted alarm signals once concentrations become high enough. In experiments where this stop mechanism was blocked, excessive swarming set in which counterintuitively reduced the swarm’s effectiveness. A measured, regulated swarm was best equipped to fight off infection. Understanding the order beneath the swarm’s chaos is key to understanding the body’s defence mechanisms, and may help turn them to therapeutic benefit.

Written by Anthony Lewis

Anthony Lewis

Writer

Ant was the web editor in the early days of BPoD, and has since worked with the UK’s top science organisations as a writer and multimedia producer. He now splits his time between freelance work and managing multimedia at The Lancet.

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• Image from work by Korbinian Kienle and colleagues, Lämmermann Lab, Max Planck Institute
• Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
• Image copyright held by the original authors
• Research published in Science, June 2021