Phenotypic and Functional Diversity in Regulatory T Cells

Louisa E. Sjaastad, David L. Owen, Sean I. Tracy, Michael A. Farrar

Research output: Contribution to journalReview articlepeer-review

15 Scopus citations


The concept that a subset of T cells exists that specifically suppresses immune responses was originally proposed over 50 years ago. It then took the next 30 years to solidify the concept of regulatory T cells (Tregs) into the paradigm we understand today – namely a subset of CD4+ FOXP3+ T-cells that are critical for controlling immune responses to self and commensal or environmental antigens that also play key roles in promoting tissue homeostasis and repair. Expression of the transcription factor FOXP3 is a defining feature of Tregs, while the cytokine IL2 is necessary for robust Treg development and function. While our initial conception of Tregs was as a monomorphic lineage required to suppress all types of immune responses, recent work has demonstrated extensive phenotypic and functional diversity within the Treg population. In this review we address the ontogeny, phenotype, and function of the large number of distinct effector Treg subsets that have been defined over the last 15 years.

Original languageEnglish (US)
Article number715901
JournalFrontiers in Cell and Developmental Biology
StatePublished - Sep 23 2021

Bibliographical note

Funding Information:
LS and DO were funded by training grant T32 AI07313 and ST was funded by training grant T32-HL007062. MF was funded by R01 AI113138.

Publisher Copyright:
© Copyright © 2021 Sjaastad, Owen, Tracy and Farrar.


  • autoimmunity
  • brain
  • differentiation
  • fat
  • muscle
  • regulatory T cells
  • skin


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