T cell

T cells or T lymphocytes are a type of lymphocyte (itself a type of white blood cell) that play a central role in cell-mediated immunity. They can be distinguished from other lymphocytes, such as B cells and natural killer cells (NK cells), by the presence of a T-cell receptor (TCR) on the cell surface. They are called T cells because they mature in the thymus (although some also mature in the tonsils).

There are several subsets of T cells, each with a distinct function.

Several Phase II and III clinical trials have demonstrated that immunotherapy can induce objective responses in otherwise refractory malignancies in tumors outside the central nervous system. In large part, effector T cells mediate much of the antitumor efficacy in these trials, and potent antitumor T cells can be generated through vaccinationimmune checkpoint blockade, adoptive cell transfer, and genetic engineering. However, activated T cells must still traffic to, infiltrate, and persist within tumor in order to mediate tumor lysis. These requirements for efficacy pose unique challenges for brain tumor immunotherapy, due to specific anatomical barriers and populations of specialized immune cells within the central nervous system that function to constrain immunity. Both autoimmune and infectious diseases of the central nervous system provide a wealth of information on how T cells can successfully migrate to the central nervous system and then engender sustained immune responses 1).

Data indicate that the leptomeninges represent a checkpoint at which activated T cells are licensed to enter the CNS parenchyma and non-activated T cells are preferentially released into the CSF, from where they can reach areas of antigen availability and tissue damage 2).

Global T cell deficiency exacerbates motor behavioral defects in a rat model of Parkinson disease 3).



Congdon KL, Sanchez-Perez LA, Sampson JH. Effective Effectors: How T cells Access and Infiltrate the Central nervous System. Pharmacol Ther. 2018 Dec 14. pii: S0163-7258(18)30229-8. doi: 10.1016/j.pharmthera.2018.12.007. [Epub ahead of print] Review. PubMed PMID: 30557632.

Schläger C, Körner H, Krueger M, Vidoli S, Haberl M, Mielke D, Brylla E, Issekutz T, Cabañas C, Nelson PJ, Ziemssen T, Rohde V, Bechmann I, Lodygin D, Odoardi F, Flügel A. Effector T-cell trafficking between the leptomeninges and the cerebrospinal fluid. Nature. 2016 Feb 18;530(7590):349-53. doi: 10.1038/nature16939. Epub 2016 Feb 10. PubMed PMID: 26863192.

Wheeler CJ, Seksenyan A, Koronyo Y, Rentsendorj A, Sarayba D, Wu H, Gragg A, Siegel E, Thomas D, Espinosa A, Thompson K, Black K, Koronyo-Hamaoui M, Pechnick R, Irvin DK. T-Lymphocyte Deficiency Exacerbates Behavioral Deficits in the 6-OHDA Unilateral Lesion Rat Model for Parkinson’s Disease. J Neurol Neurophysiol. 2014 May;5(3). pii: 209. PubMed PMID: 25346865.

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