Intracerebral regulation of immune responses

Major I progress has, been made over the last years in our understanding of the mechanisms underlying immune privilege and immune surveillance of the central nervous system (CNS). Once considered a passive process relying onl y on physical barriers, immune privilege is now viewed as a more complex ph enomenon, which involves active regulation of immune reactivity by the CNS microenvironment. Evidence has also emerged that the immune system continuo usly and effectively patrols the CNS and that dysregulated immune responses against CNS-associated (exogenous or self) antigens are involved in the pa thogenesis of various neurological diseases. In this article we shall brief ly review current knowledge of how the immune, response is regulated locall y in the CNS and which. cell types and molecular mechanisms are involved in shaping intracerebral immune responses.