Evidence for γδ T cells with a restricted Vδ6 junctional region in the normal mouse central nervous system

Abstract

In this study we present evidence that γδ T cells are present in the normal mouse central nervous system (CNS). Compared with matching spleen γδ T cells, CNS γδ T cells expressed only the CD45RB low phenotype, suggesting that CNS γδ T cells belong to the memory cell population. Approximately 20% expressed exclusively the CD8αβ heterodimer, consistent with a thymic origin. γδ T cells in both spleen and CNS expressed higher levels of the IL-2rβ (CD122), as well as Fas and FasL, than αβ T cells, suggesting that these cells function as immunoregulatory T cells. RT-PCR analysis showed almost exclusive use of Vδ6 in the CNS whereas more Vδ genes were expressed in the spleen. Sequencing of Vδ6 RT-PCR products demonstrated a polyclonal population of T cells in the spleen but a more clonal population within the CNS. The predominant CNS sequence was found in all animals studied and was also detected in the spleen. From these data we conclude that a selective component of circulating γδ T cells traffics through the CNS. Thus, all major populations of lymphocytes can be detected in the normal CNS and as such may play specific roles in the immunological surveillance of that organ.