CD8+ T cells primed in the periphery provide time-bound immune-surveillance to the central nervous system

KG Young, S MacLean, R Dudani… - The Journal of …, 2011 - journals.aai.org
KG Young, S MacLean, R Dudani, L Krishnan, S Sad
The Journal of Immunology, 2011journals.aai.org
After vaccination, memory CD8+ T cells migrate to different organs to mediate immune
surveillance. In most nonlymphoid organs, following an infection, CD8+ T cells differentiate
to become long-lived effector-memory cells, thereby providing long-term protection against a
secondary infection. In this study, we demonstrated that Ag-specific CD8+ T cells that
migrate to the mouse brain following a systemic Listeria infection do not display markers
reminiscent of long-term memory cells. In contrast to spleen and other nonlymphoid organs …
Abstract
After vaccination, memory CD8+ T cells migrate to different organs to mediate immune surveillance. In most nonlymphoid organs, following an infection, CD8+ T cells differentiate to become long-lived effector-memory cells, thereby providing long-term protection against a secondary infection. In this study, we demonstrated that Ag-specific CD8+ T cells that migrate to the mouse brain following a systemic Listeria infection do not display markers reminiscent of long-term memory cells. In contrast to spleen and other nonlymphoid organs, none of the CD8+ T cells in the brain reverted to a memory phenotype, and all of the cells were gradually eliminated. These nonmemory phenotype CD8+ T cells were found primarily within the choroid plexus, as well as in the cerebrospinal fluid-filled spaces. Entry of these CD8+ T cells into the brain was governed primarily by CD49d/VCAM-1, with the majority of entry occurring in the first week postinfection. When CD8+ T cells were injected directly into the brain parenchyma, cells that remained in the brain retained a highly activated (CD69 hi) phenotype and were gradually lost, whereas those that migrated out to the spleen were CD69 low and persisted long-term. These results revealed a mechanism of time-bound immune surveillance to the brain by CD8+ T cells that do not reside in the parenchyma.
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