Immune Privilege in the Central Nervous System: Implications for Neuroinflammatory Diseases

The central nervous system (CNS) has long been considered an immune-privileged site, where immune responses are tightly regulated to protect neural tissue from inflammation-induced damage. Immune privilege in the CNS is maintained through various mechanisms, including the blood-brain barrier (BBB), the absence of conventional lymphatic drainage, the specialized function of CNS-resident immune cells, and the expression of immunosuppressive molecules like TGF-β and IL-10. These protective systems are essential for preserving CNS homeostasis, as uncontrolled immune activity in the CNS can lead to irreversible damage to neurons and glial cells. However, immune privilege is not absolute. In neuroinflammatory diseases such as multiple sclerosis (MS), neuromyelitis optica (NMO), and Alzheimer’s disease, immune privilege is breached, resulting in the infiltration of immune cells, chronic inflammation, and progressive neural damage. The breakdown of the BBB, immune cell activation, and dysregulated inflammation contribute to the pathophysiology of these diseases. This review examines the mechanisms that underlie immune privilege in the CNS, how these systems are compromised in neuroinflammatory conditions, and the therapeutic implications for modulating immune responses in the CNS. Targeted therapies aimed at restoring immune regulation and preserving CNS function offer promising prospects for treating neuroinflammatory diseases and maintaining CNS health. Keywords: Immune Privilege, Central Nervous System, Neuroinflammatory Diseases, Blood-Brain Barrier, Multiple Sclerosis, Immunosuppressive Mechanisms