Inflammatory cytokines in the brain: does the CNS shape immune responses?

Immune responses in the central nervous system (CNS) have traditionally been regarded as representing the intrusion of an unruly, ill-behaved mob of leukocytes into the well-ordered and organized domain of thought and reason. However, results accumulated over the past few years suggest that, far from being an immunologically privileged organ, T lymphocytes may be regular and frequent visitors to the CNS, for purposes of immune surveillance. Here, Trevor Owens and colleagues propose that the brain itself can regulate or shape immune responses therein. Furthermore, given that the immune cells may be subverted to autoimmunity, they suggest that the study of inflammatory autoimmune disease in the brain may shed light on the ability of the local environment to regulate immune responses.