Neural Functions of Hematopoietic-derived Cells

The immune system and the central nervous system (CNS) are more alike than different. Much of the transport into and out of the CNS across the blood-brain barrier (BBB) follows the canonical paradigm seen in other organs, i.e. nutrients, water, and glucose comprising the bulk of influx, with metabolites and toxins moving in the other direction back into the circulation. The immune privilege of the brain is often thought to mean that the immune system simply ignores the brain except in situations of pathological disturbance. Evidence that T-cells are important in modulating the resolution of CNS neurodegeneration comes from other pathologies as well. Neuroinflammation is a hallmark of amyotrophic lateral sclerosis (ALS), and it has been thought that lymphocyte infiltration seen in ALS lesions was evidence of immune-mediated destruction of neurons, and initiated by T-cells.