摘要
Distinct migratory pathways and trafficking of dendritic cells to the central nervous system (CNS): The immune system is a host defense mechanism protecting against invaders, such as bacteria and viruses, while maintaining tolerance to self. Nonetheless, a few sites throughout the body are believed to be immunologically inert, such as the testes, the eye and the brain. Indeed, experiments in the mid-20th century gave rise to the concept of the brain as a site of immune privilege. Originally, the immune privilege of the brain was thought to be absolute, attributed by a physical blood-brain barrier (BBB) protecting the CNS from the entry of pathogens and circulating immune cells. These views have changed and currently, the CNS is seen as an immune-specialized site regulated by immunological components into and within the CNS.
