Neuronal regulation of immune responses in the central nervous system.

The central nervous system (CNS) has traditionally been considered to be immunologically privileged, but over the years there has been a re-evaluation of this dogma. To date, studies have tended to focus on the immune functions of glial cells, whereas the roles of neurons have been regarded as passive and their immune-regulatory properties have been less examined. However, recent findings indicate that CNS neurons actively participate in immune regulation by controlling their glial cell counterparts and infiltrated T cells. Here, we describe the immune-regulatory roles of CNS neurons by both contact-dependent and contact-independent mechanisms. In addition, we specifically deal with the immune functions of neuronal cell adhesion molecules, many of which are key modulators of neuronal synaptic formation and plasticity.