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Simultaneous Quantification of Selected Kynurenines Analyzed by Liquid Chromatography-Mass Spectrometry in Medium Collected from Cancer Cell Cultures
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Levo- but not dextro-1-methyl tryptophan abrogates the IDO activity of human dendritic cells

Stefan Lob1, Alfred Konigsrainer, Richard Schafer

  • 1Department of General, Visceral and Transplant Surgery, University Hospital of Tubingen, Tubingen, Germany.

Blood
|November 30, 2007
PubMed

Clinical trials have been started with the aim of inducing tumor immunity by blocking the immunosuppressive action of indoleamine-2,3-dioxygenase (IDO) with the IDO2-inhibitor dextro-1-methyl-tryptophan (D-1MT). Here we show that human dendritic cells (DCs) express both IDO-1 and IDO-2, but that only IDO1 mediates tryptophan catabolism; furthermore, its activity is blocked by levo-1MT, whereas D-1MT is inefficient. Consequently, in humans any possible antitumor effects of D-1MT cannot be attributed to abrogation of IDO activity in DCs as described in this study.

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