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Human myeloid dendritic cells are refractory to tryptophan metabolites.
MedLine Citation:
PMID:  21699942     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
The enzyme indoleamine 2,3-dioxygenase (IDO) degrades the essential amino acid tryptophan and is expressed, among other cell types, in immune cells such as dendritic cells (DCs), monocytes, and macrophages. It has been shown that the activity of IDO has a broad regulatory function in the immune system by inhibiting effector T-cell responses, inducing regulatory T cells and facilitating the development of regulatory DCs. The degradation of tryptophan has 2 consequences, both of which have been postulated to be physiologically relevant, namely the reduction of tryptophan levels and the accumulation of tryptophan catabolites. Recently, we have shown that DCs that had differentiated under low-tryptophan conditions acquire a tolerogenic phenotype with increased expression of the inhibitory receptors immunoglobulin-like transcript 2 (ILT2), ILT3, and ILT4. In the present study, we investigated the effect of distinct tryptophan catabolites on the function of human DCs and the expression of ILT2, ILT3, and ILT4 on these cells. We show that, in contrast to low tryptophan levels alone, the combination of several metabolites along the tryptophan-kynurenine degradation pathway during DC differentiation does not induce ILT2, ILT3, or ILT4 on these DCs and does not reduce the T-cell stimulatory capacity of these DCs.
Authors:
Dagmar von Bubnoff; Helene Wilms; Marina Scheler; Manuela Brenk; Susanne Koch; Thomas Bieber
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-6-20
Journal Detail:
Title:  Human immunology     Volume:  -     ISSN:  1879-1166     ISO Abbreviation:  -     Publication Date:  2011 Jun 
Date Detail:
Created Date:  2011-6-24     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8010936     Medline TA:  Hum Immunol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2011. Published by Elsevier Inc.
Affiliation:
Department of Dermatology and Allergology, Friedrich-Wilhelms-University, Bonn, Germany.
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