Homeostasis and function of regulatory T cells (Tregs) in vivo:lessons from TCR-transgenic Tregs

Attridge, Kesley and Walker, Lucy S.K. Homeostasis and function of regulatory T cells (Tregs) in vivo:lessons from TCR-transgenic Tregs. Immunological Reviews, 259 (1), pp. 23-39.

Abstract

The identification of CD25 and subsequently Forkhead box protein 3 (Foxp3) as markers for regulatory T cells (Tregs) has revolutionized our ability to explore this population experimentally. In a similar vein, our understanding of antigen-specific Treg responses in vivo owes much to the fortuitous generation of T-cell receptor (TCR)-transgenic Tregs. This has permitted tracking of Tregs with a defined specificity in vivo, facilitating analysis of how encounter with cognate antigen shapes Treg homeostasis and function. Here, we review the key lessons learned from a decade of analysis of TCR-transgenic Tregs and set this in the broader context of general progress in the field. Use of TCR-transgenic Tregs has led to an appreciation that Tregs are a highly dynamic proliferative population in vivo, rather than an anergic population as they were initially portrayed. It is now clear that Treg homeostasis is positively regulated by encounter with self-antigen expressed on peripheral tissues, which is likely to be relevant to the phenomenon of peripheral repertoire reshaping that has been described for Tregs and the observation that the Treg TCR specificities vary by anatomical location. Substantial evidence has also accumulated to support the role of CD28 costimulation and interleukin-2 in Treg homeostasis. The availability of TCR-transgenic Tregs has enabled analysis of Treg populations that are sufficient or deficient in particular genes, without the comparison being confounded by repertoire alterations. This approach has yielded insights into genes required for Treg function in vivo, with particular progress being made on the role of ctla-4 in this context. As the prospect of manipulating Treg populations in the clinic becomes reality, a full appreciation of the rules governing their homeostasis will prove increasingly important.

Publication DOI: https://doi.org/10.1111/imr.12165
Divisions: Life & Health Sciences
Additional Information: © 2014 The Authors. Immunological Reviews Published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Uncontrolled Keywords: antigen-mediated clonal selection,antigen,homeostasis,T-cell,immune tolerance,lymphocyte activation,receptors,signal transduction,regulatory T-lymphocytes,thymus gland,immune regulation,Tregs,tolerance,TCR-transgenic,Treg proliferation,Treg function

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