Characteristics of differentiated CD8+ and CD4+ T cells present in the human brain

J Smolders, EBM Remmerswaal, KG Schuurman… - Acta …, 2013 - Springer
J Smolders, EBM Remmerswaal, KG Schuurman, J Melief, CG van Eden, RAW van Lier…
Acta neuropathologica, 2013Springer
Immune surveillance of the central nervous system (CNS) by T cells is important to keep
CNS-trophic viruses in a latent state, yet our knowledge of the characteristics of CNS-
populating T cells is incomplete. We performed a comprehensive, multi-color flow-cytometric
analysis of isolated T cells from paired corpus callosum (CC) and peripheral blood (PB)
samples of 20 brain donors. Compared to PB, CC T cells, which were mostly located in the
perivascular space and sporadically in the parenchyma, were enriched for cells expressing …
Abstract
Immune surveillance of the central nervous system (CNS) by T cells is important to keep CNS-trophic viruses in a latent state, yet our knowledge of the characteristics of CNS-populating T cells is incomplete. We performed a comprehensive, multi-color flow-cytometric analysis of isolated T cells from paired corpus callosum (CC) and peripheral blood (PB) samples of 20 brain donors. Compared to PB, CC T cells, which were mostly located in the perivascular space and sporadically in the parenchyma, were enriched for cells expressing CD8. Both CD4+ and CD8+ T cells in the CC had a late-differentiated phenotype, as indicated by lack of expression of CD27 and CD28. The CC contained high numbers of T cells expressing chemokine receptor CX3CR1 and CXCR3 that allow for homing to inflamed endothelium and tissue, but hardly cells expressing the lymph node-homing receptor CCR7. Despite the late-differentiated phenotype, CC T cells had high expression of the IL-7 receptor α-chain CD127 and did not contain the neurotoxic cytolytic enzymes perforin, granzyme A, and granzyme B. We postulate that CNS T cells make up a population of tissue-adapted differentiated cells, which use CX3CR1 and CXCR3 to home into the perivascular space, use IL-7 for maintenance, and lack immediate cytolytic activity, thereby preventing immunopathology in response to low or non-specific stimuli. The presence of these cells in this tightly regulated environment likely enables a fast response to local threats. Our results will enable future detailed exploration of T-cell subsets in the brain involved in neurological diseases.
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