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Open Access Research

Indoleamine 2,3-dioxygenase expression in patients with allergic rhinitis: a case-control study

Annika Luukkainen1, Jussi Karjalainen2, Teemu Honkanen34, Mikko Lehtonen56, Timo Paavonen47 and Sanna Toppila-Salmi89*

Author Affiliations

1 Department of Otorhinolaryngology, University of Tampere, Tampere, Finland

2 Allergy Centre, Tampere University Hospital, Tampere, Finland

3 Department of Otorhinolaryngology, Kanta-Hame Central Hospital, Hameenlinna, Finland

4 Department of Pathology, University of Tampere, Tampere, Finland

5 Department of Otorhinolaryngology, University of Tampere, Tampere, Finland

6 Department of Otorhinolaryngology, Kanta-Hame Central Hospital, Hameenlinna, Finland

7 Department of Pathology, Centre for Laboratory Medicine, Tampere University Hospital, Tampere, Finland

8 Helsinki University Hospital, Skin and Allergy Hospital, Helsinki, Finland

9 Transplantation laboratory, Haartman Institute, University of Helsinki, Helsinki, Finland

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Clinical and Translational Allergy 2011, 1:17  doi:10.1186/2045-7022-1-17

Published: 12 December 2011

Abstract

Background

Indoleamine 2,3-dioxygenase (IDO) is a tryptophan catalyzing enzyme. It has been suggested that it has a role in lower airway allergic inflammations, but its role in allergic rhinitis has not been investigated.

Objective

Our aim was to evaluate the expression of IDO in the nasal mucosa of allergic rhinitis patients allergic to birch pollen during peak exposure to birch pollen allergen and compare it to non-atopic patients.

Methods

IDO expression was immunohistochemically evaluated from nasal specimens obtained in- and off-season from otherwise healthy non-smoking volunteers both allergic to birch pollen (having mild or moderate allergic rhinoconjunctivitis) and non-allergic controls. Results: The IDO expression levels were low in healthy controls and remained low also in patients allergic to birch pollen. There were no differences in the expression of IDO in- and off-season in either healthy or allergic subjects.

Conclusions

There is a controversy in the role of IDO in upper and lower airways during allergic airway disease. It seems that IDO is associated to allergic inflammations of the lower airways, but does not have a local role in the nasal cavity at least in mild or moderate forms of allergic rhinitis.

Keywords:
Indoleamine 2,3-dioxygenase; allergic rhinitis; birch pollen; dendritic cell; tryptophan; kynurenine; interferon gamma; leukocyte; eosinophil