The meninges host a distinct compartment of regulatory T cells that preserves brain homeostasis

Our understanding of the meningeal immune system has recently burgeoned, particularly regarding how innate and adaptive effector cells are mobilized to meet brain challenges. However, information on how meningeal immunocytes guard brain homeostasis in healthy individuals remains limited. This study highlights the heterogeneous, polyfunctional regulatory T cell (T reg ) compartment in the meninges. A T reg subtype specialized in controlling interferon-γ (IFN-γ) responses and another dedicated to regulating follicular B cell responses were substantial components of this compartment. Accordingly, punctual T reg ablation rapidly unleashed IFN-γ production by meningeal lymphocytes, unlocked access to the brain…