Indoleamine 2,3-Dioxygenase and Regulatory Function: Tryptophan Starvation and Beyond

  • Ciriana Orabona
  • Ursula GrohmannEmail author
Part of the Methods in Molecular Biology book series (MIMB, volume 677)


Indoleamine 2,3-dioxygenase (IDO) is an ancestral enzyme that, initially confined to the regulation of tryptophan availability in local tissue microenvironments, is now considered to play a wider role that extends to homeostasis and plasticity of the immune system. Thus, IDO biology has many implications for many aspects of immunopathology, including viral infections, neoplasia, autoimmunity, and chronic inflammation. Its immunoregulatory effects are mainly mediated by dendritic cells (DCs) and involve not only tryptophan deprivation but also production of kynurenines that act on IDO DCs – thus rendering an otherwise stimulatory DC capable of regulatory effects – as well as on T cells. As a result, IDO+ DCs mediate multiple effects on T lymphocytes, including inhibition of proliferation, apoptosis, and differentiation toward a regulatory phenotype.

Key words

IDO Tryptophan catabolism Amino acid starvation Kynurenines Dendritic cells Regulatory T cells 



The Authors would like to thank Gianluca Andrielli for digital art.


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Copyright information

© Humana Press 2010

Authors and Affiliations

  1. 1.Department of Experimental Medicine and Biochemical SciencesUniversity of PerugiaPerugiaItaly

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