Summary
Swarming is a collective movement that has far-reaching implications in biology and beyond. Swarms involve groups of individuals coordinating their behavior in a self-organizing process. Examples include swarming motility and quorum sensing in bacteria (1), foraging in ants, and the defensive actions of honey bees. In the animal immune system, swarms of white blood cells called neutrophils respond to microbial threats and tissue damage by traveling en masse to affected tissues. Although much work has been done to understand the initiation of neutrophil swarms (2), less is known about how they are terminated. On page 1303 of this issue, Kienle et al. (3) reveal that neutrophils limit their swarms by deactivating their own receptors that detect self-produced swarm signals. This desensitization limits neutrophil aggregation and, crucially, promotes pathogen clearance and resolution of acute inflammatory responses.