Indoleamine 2,3-dioxygenase and tumor-induced tolerance

David H. Munn, Andrew L. Mellor

Research output: Contribution to journalReview article

717 Scopus citations


Tumors arise from normal cells of the body through genetic mutation. Although such genetic mutation often leads to the expression of abnormal antigens, the immune system fails to respond effectively to these antigens; that is, it is tolerant of these antigens. This acquired state of tolerance must be overcome for cancer immunotherapy to succeed. Indoleamine 2,3-dioxygenase (IDO) is one molecular mechanism that contributes to tumor-induced tolerance. IDO helps create a tolerogenic milieu in the tumor and the tumor-draining lymph nodes, both by direct suppression of T cells and enhancement of local Treg-mediated immunosuppression. It can also function as an antagonist to other activators of antitumor immunity. Therefore, strategies to block IDO might enhance the effectiveness of tumor immunotherapy.

Original languageEnglish (US)
Pages (from-to)1147-1154
Number of pages8
JournalJournal of Clinical Investigation
Issue number5
StatePublished - May 1 2007


ASJC Scopus subject areas

  • Medicine(all)

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