In Vitro Induction of Human Regulatory T Cells Using Conditions of Low Tryptophan Plus Kynurenines

Keli L Hippen, R. S. O'Connor, A. M. Lemire, Asim Saha, E. A. Hanse, N. C. Tennis, S. C. Merkel, Ameeta Kelekar, J. L. Riley, B. L. Levine, C. H. June, L. A. Turka, L. S. Kean, Margaret L MacMillan, Jeffrey S Miller, John E Wagner, D. H. Munn, Bruce R Blazar

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


Thymic regulatory T cells (tTregs) and induced regulatory T cells (iTregs) suppress murine acute graft-versus-host disease (GVHD). Previously, we demonstrated that the plasmacytoid dendritic cell indoleamine 2,3-dioxygenase (IDO) fosters the in vitro development of human iTregs via tryptophan depletion and kynurenine (Kyn) metabolites. We now show that stimulation of naïve CD4+ T cells in low tryptophan (low Trp) plus Kyn supports human iTreg generation. In vitro, low Trp + Kyn iTregs and tTregs potently suppress T effector cell proliferation equivalently but are phenotypically distinct. Compared with tTregs or T effector cells, bioenergetics profiling reveals that low Trp + Kyn iTregs have increased basal glycolysis and oxidative phosphorylation and use glutaminolysis as an energy source. Low Trp + Kyn iTreg viability was reliant on interleukin (IL)-2 in vitro. Although in vivo IL-2 administration increased low Trp + Kyn iTreg persistence on adoptive transfer into immunodeficient mice given peripheral blood mononuclear cells to induce GVHD, IL-2–supported iTregs did not improve recipient survival. We conclude that low Trp + Kyn create suppressive iTregs that have high metabolic needs that will need to be addressed before clinical translation.

Original languageEnglish (US)
Pages (from-to)3098-3113
Number of pages16
JournalAmerican Journal of Transplantation
Issue number12
StatePublished - Dec 2017

Bibliographical note

Publisher Copyright:
© 2017 The American Society of Transplantation and the American Society of Transplant Surgeons


  • T cell biology
  • basic (laboratory) research/science
  • bone marrow/hematopoietic stem cell transplantation
  • graft-versus-host disease (GVHD)
  • immune regulation
  • immunosuppression/immune modulation
  • tolerance: clinical
  • translational research/science
  • xenotransplantation


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