Inside every human body, a conversation is happening that scientists never knew existed until now.
Researchers at the University of Münster and Ruhr University Bochum in Germany have discovered that immune cells called neutrophils — the most common type of white blood cell in humans — communicate using the same chemical signals that brain nerve cells use. These tiny defenders take up substances called catecholamines (which include dopamine and adrenaline), store them in tiny packages inside the cell, and release them when the body faces infection or inflammation.
"We were surprised to see how similar neutrophils and neurons are in their ability to handle neurotransmitters," said Professor Luise Erpenbeck, one of the study's lead researchers.
Until recently, scientists simply did not have the tools to watch this process happening in real time. The team solved this problem by using fluorescent carbon nanotube sensors — incredibly tiny detectors that glow when they encounter catecholamines. For the first time, researchers could watch individual living immune cells release these signals under a microscope.
The discovery, published in the journal Advanced Science, showed that when neutrophils release these neurotransmitters, they do two important things: they calm down excessive immune responses (preventing the body from damaging itself) while simultaneously encouraging blood clotting. This reveals a direct link between the immune system and the blood vessels.
The researchers also tested their findings in living people. They induced mild inflammation in healthy volunteers and measured changes in gene activity. The results confirmed that neutrophils coordinate their neurotransmitter receptors and production programs during inflammation — not just in lab dishes, but inside actual human bodies.
"Until now, we simply lacked the methods to visualize such processes directly in living immune cells," said Professor Sebastian Kruss, who co-led the research. "What we have now observed fundamentally changes our understanding of these cells."
This new understanding could eventually help scientists develop better treatments for conditions where the immune system goes haywire, like severe allergic reactions or autoimmune diseases. But for now, the discovery simply shows how much more there is to learn about the body's natural defenses — and how similar the immune system and nervous system really are.