Key players for T-cell regeneration.
OBJECTIVE
The thymus provides a unique and essential microenvironment for T-cell precursors to develop into mature functionally competent T lymphocytes. Ageing causes architectural changes in the thymus resulting in a loss of thymic epithelial space required for thymopoiesis - a process known as thymic involution. Additionally, cytoablative regimens used to treat malignancies also destroy thymic architecture. The net result of both processes is diminished thymic output and function that may lead to impaired immunity. Thus, immunocompromised individuals would benefit from strategies aimed at enhancing T-cell reconstitution.


RESULTS
Here we discuss strategies such as the use of sex steroid ablation, keratinocyte growth factor, interleukin-7, and in-vitro-generated progenitor T cells as candidates for restoring T-cell immunity. Using various animal models of ageing or hematopoietic stem cell transplantation, these strategies have been shown to restore thymic architecture and cellularity, resulting in increased output and T-cell function in the periphery.


CONCLUSIONS
These candidate approaches are currently being tested in clinical trials, with preliminary evidence showing encouraging effects on T-cell reconstitution. Nevertheless, although these strategies show clear promise in animal models, and in early human trials, further data are needed to determine their efficacy in patients.
Awong
Génève
G
Department of Immunology, University of Toronto, and Sunnybrook Research Institute, Toronto, Ontario, Canada.
LaMotte-Mohs
Ross
R
Zúñiga-Pflücker
Juan Carlos
JC
D000818:Animals; D002986:Clinical Trials as Topic; D051523:Fibroblast Growth Factor 7 / Q000494:pharmacology; D018380:Hematopoietic Stem Cell Transplantation / Q000379:methods; D006801:Humans; D015851:Interleukin-7 / Q000494:pharmacology; D012038:Regeneration / Q000187:drug effects / Q000276:immunology / Q000502:physiology*; D013601:T-Lymphocytes / Q000276:immunology / Q000502:physiology*; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology / Q000502:physiology*
D015851:Interleukin-7; D051523:Fibroblast Growth Factor 7