Interactions between the mind and the body have sparked the interest of scientists and philosophers for centuries. In ancient Greece, the physician Galen described the spleen as being the source of black bile, which was thought to cause melancholy when secreted in excess. Today, research is uncovering complex ways in which the brain and body interact to affect diverse aspects of health, from mood to immune function. The spleen aids immune defences by functioning as part of the lymphatic system; the organ is a major hub of activities needed to initiate responses in the adaptive branch of the immune system, which handles defences that are tailored to a specific disease-causing agent.
The spleen is a target of top-down control from the brain1. Writing in Nature, Zhang et al.2 have taken our understanding of brain–spleen connections to the next level by revealing an aspect of top-down control that regulates the adaptive immune system….
