Figure 1.

Spleen–brain communication after stroke. The ischemic brain stimulates the autonomic nervous system and releases chemotactic factors or CNS antigens to trigger the efflux of immune cells from the spleen to the site of brain injury. At the site of injury, inflammatory cells migrate through the compromised blood–brain barrier and enter the brain with a large amount of chemokines/cytokines, free radicals, and other inflammatory mediators. These factors are thought to exacerbate brain injury in the acute phases of stroke.