How the brain communicates with the immune system
Experiments on mice have identified the missing link that allows the nervous and immune systems to communicate. The findings provide a physical link between the brain and the inflammatory response for the first time, uncovering the secrets of the mind's power over the body.
Inflammatory responses can occur for a number of reasons, a common one being infection. However, often such a response can be damaging and must be limited by the body to prevent unnecessary damage being done.
Scientists have observed that by stimulating the Vagus nerve, the inflammatory response in the spleen can be turned off. The problem scientists faced was that the Vagus nerve does not produce the chemical acetyl choline, which acts as a signal to instruct immune cells to stop the inflammatory response. They could not understand how the two systems were communicating.
But now scientists have found the missing link: specialised immune cells called CD4 lymphocytes. Using mice that lack these cells the scientists found that the Vagus nerve was unable to turn off the inflammatory response. Only when the mice received CD4 lymphocytes in a transfusion was the response turned off.
The research shows that the Vagus nerve activates the CD4 lymphocytes, which in turn release the acetyl choline signal to regulate the immune cells involved in the inflammatory response. Although the research focussed on these cells in the spleen they are found throughout the body. The authors believe that the nervous system probably controls the response in other organs and tissues as well.