TCR signal strength during positive selection shapes CD25 expression patterns on thymically derived regulatory T cells
- 1University of California, Berkeley
Abstract
Regulatory T cells (Tregs) are a suppressive subset of CD4 T cells that maintain immune homeostasis. Most Tregs develop in the thymus but how thymic selection impacts peripheral Treg fate remains unknown. Here we show that the strength of TCR signal experienced during positive selection in the thymic cortex impacts how CD4 SP thymocytes respond to Treg inducing signals in the medulla. Thymocytes that experienced weak signals during positive selection (identified as CD5LO CD4 SP) show a greater dependence on TGF-{beta} than IL-2 for Treg induction and produce Foxp3+ cells that lack constitutive expression of the classic Treg marker CD25. Moreover, CD4 clones that give rise to CD25- thymic Tregs also produce CD25- peripheral Tregs. These data indicate that positive selection provides critical context for how CD4 T cells respond to TCR agonist and cytokine signals, leading to an alternative lineage of Tregs that lacks constitutive CD25 expression.
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BibTeX
@misc{baldwin2026signal,
title = {{TCR signal strength during positive selection shapes CD25 expression patterns on thymically derived regulatory T cells}},
author = {I. Baldwin and D. Zhang and Y. Kulkarni and W. Chen and E. Robey},
howpublished = {bioRxiv},
year = {2026},
month = jun,
doi = {10.64898/2026.06.16.732736},
url = {https://www.biorxiv.org/content/10.64898/2026.06.16.732736v2},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - TCR signal strength during positive selection shapes CD25 expression patterns on thymically derived regulatory T cells
AU - I. Baldwin
AU - D. Zhang
AU - Y. Kulkarni
AU - W. Chen
AU - E. Robey
PY - 2026
DA - 2026/06/16
PB - bioRxiv
DO - 10.64898/2026.06.16.732736
UR - https://www.biorxiv.org/content/10.64898/2026.06.16.732736v2
AB - Regulatory T cells (Tregs) are a suppressive subset of CD4 T cells that maintain immune homeostasis. Most Tregs develop in the thymus but how thymic selection impacts peripheral Treg fate remains unknown. Here we show that the strength of TCR signal experienced during positive selection in the thymic cortex impacts how CD4 SP thymocytes respond to Treg inducing signals in the medulla. Thymocytes that experienced weak signals during positive selection (identified as CD5LO CD4 SP) show a greater dependence on TGF-{beta} than IL-2 for Treg induction and produce Foxp3+ cells that lack constitutive expression of the classic Treg marker CD25. Moreover, CD4 clones that give rise to CD25- thymic Tregs also produce CD25- peripheral Tregs. These data indicate that positive selection provides critical context for how CD4 T cells respond to TCR agonist and cytokine signals, leading to an alternative lineage of Tregs that lacks constitutive CD25 expression.
ER -