A primary defense strategy in response to infection or inflammation is to mobilize innate immune cells through the circulatory system to the affected organ. Patrolling monocytes and neutrophils constantly monitor healthy tissue and extravasate from vascular endothelium to infected or injured tissue through a stepwise mechanism (1). On page 409 of this issue, Cugurra et al. (2) demonstrate in a mouse model a pathway by which the central nervous system (CNS) bypasses this circulatory patrol system and supplies the meninges (the membranes that enclose the brain and spinal cord) with functionally distinct myeloid cells through channels that traverse the skull bone marrow. Moreover, on page 408 of this issue, Brioschi et al. (3) demonstrate that the meninges are also populated with B cells directly derived from skull marrow hematopoiesis. These studies show that the brain is an immunologically distinct organ that is surrounded by its own cadre of immune cells.

应对感染或炎症的主要防御策略是通过循环系统将先天免疫细胞动员到受影响的器官。巡逻单核细胞和中性粒细胞通过逐步机制不断监测健康组织和从血管内皮到感染或受伤组织的渗出物 ( 1 )。在本期第 409 页，Cugurra等人。( 2 ) 在小鼠模型中展示了一条通路，通过该通路，中枢神经系统 (CNS) 绕过该循环巡逻系统并通过穿过颅骨的通道为脑膜（包围大脑和脊髓的膜）提供功能不同的髓样细胞。骨髓。此外，在本期第 408 页，Brioschi等人。(3 ) 证明脑膜也填充有直接源自颅骨骨髓造血的 B 细胞。这些研究表明，大脑是一个免疫学上独特的器官，周围环绕着自己的免疫细胞。