ArticleClinical and experimental immunology2006
The activity of the immunoregulatory enzyme indoleamine 2,3-dioxygenase is decreased in smokers.
Article in Clinical and experimental immunology, 2006. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 17 papers.
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Who cites it
17 citing papers in PubMed, 37 citations in OpenAlex.
- Tryptophan metabolism: A hidden regulator of female reproductive health beyond fertility.Chinese medical journal · 2026Review
- Shifts in amino acids profile in chronic pancreatitis.PloS one · 2026Article
- Periconceptional Non-medical Maternal Determinants Influence the Tryptophan Metabolism: The Rotterdam Periconceptional Cohort (Predict Study).International journal of tryptophan research : IJTR · 2024Article
- Associations of Parameters of the Tryptophan-Kynurenine Pathway with Cardiovascular Risk Factors in Hypertensive Patients.Nutrients · 2023Article
- Changes in Tryptophan-Kynurenine Metabolism in Patients with Depression Undergoing ECT-A Systematic Review.Pharmaceuticals (Basel, Switzerland) · 2022Review
- IDO/kynurenine pathway in cancer: possible therapeutic approaches.Journal of translational medicine · 2022Review
- Is Poor Lithium Response in Individuals with Bipolar Disorder Associated with Increased Degradation of Tryptophan along the Kynurenine Pathway? Results of an Exploratory Study.Journal of clinical medicine · 2022Article
- Epstein-Barr Virus Infection in Lung Cancer: Insights and Perspectives.Pathogens (Basel, Switzerland) · 2022Review
- Tracking TRYCAT: A Critical Appraisal of Kynurenine Pathway Quantifications in Blood.Frontiers in pharmacology · 2022Article
- Kynurenine/Tryptophan Ratio as a Potential Blood-Based Biomarker in Non-Small Cell Lung Cancer.International journal of molecular sciences · 2021Article
- Article
- Markers of Inflammation and Monoamine Metabolism Indicate Accelerated Aging in Bipolar Disorder.Frontiers in psychiatry · 2018Article
- Blood Levels of Monoamine Precursors and Smoking in Patients with Schizophrenia.Frontiers in public health · 2016Article
- Serum concentrations of kynurenines in adult patients with attention-deficit hyperactivity disorder (ADHD): a case-control study.Behavioral and brain functions : BBF · 2015Article
- Interferon gamma (IFN-γ)-mediated inflammation and the kynurenine pathway in relation to risk of hip fractures: the Hordaland Health Study.Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA · 2014Article
- Interferon (IFN)-γ-mediated inflammation and the kynurenine pathway in relation to bone mineral density: the Hordaland Health Study.Clinical and experimental immunology · 2014Article
- A community-based study on determinants of circulating markers of cellular immune activation and kynurenines: the Hordaland Health Study.Clinical and experimental immunology · 2013Article
Corrections and comments
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Authors and funding
6 authors at 3 institutions in 1 country.
Funding
No grant is acknowledged in the PubMed record.
Abstract
Indoleamine 2,3-dioxygenase (IDO), an enzyme involved in the degradation of the essential amino acid tryptophan (trp) to its main metabolite kynurenine (kyn), suppresses T cell activity. Smoking has marked immunomodulatory effects, above all immunosuppressive, causing a reduction in the levels of immunoglobulins and an increased risk of infections. The immunostimulatory effects of smoking are manifested, for example, in increased autoantibody production. We sought to establish whether IDO activity is involved in the immunomodulatory effects of smoking. To this end we measured the ratio of kyn to trp, reflecting IDO activity, by reverse-phase high-performance liquid chromatography (HPLC) in 784 (464 female, 230 male) subjects of a population-based sample of the adult Finnish population. Serum cotinine concentration as an indicator of active smoking was measured in the patients by radioimmunoassay and detailed data gathered on smoking habits. IDO activity was lower in smokers in this population-based sample compared with non-smokers when active smoking was classified according to serum cotinine concentration or history of smoking habits. Moreover, serum IDO activity correlated inversely with serum cotinine concentration. In conclusion, the activity of the IDO enzyme is decreased in smoking subjects, and the reduction in IDO-dependent immunosuppression could thus be responsible for the known immunostimulatory effects of smoking.
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