title: Serum indolamine 2,3 dioxygenase as a marker in the evaluation of allergic rhinitis.
abstract: BACKGROUND
  Allergic rhinitis occurs on exposure to a known allergen and is correlated with a positive skin test and physical examination results. Tryptophan is a substrate of many important proteins, e.g., indolamine 2,3 dioxygenase (IDO). IDO, an immunomodulator, is a metabolic enzyme induced by immune activation. It has a significant role in allergic reactions. T-helper 2 cell is proposed to affect the expression of IDO.
  
  
  OBJECTIVE
  To evaluate IDO levels in patients with allergic rhinitis compared with controls and its relationship to the severity of allergic rhinitis.
  
  
  METHODS
  This case-control study included 20 patients who were atopic and with allergic rhinitis who attended the allergy clinic of Ain Shams University Hospitals. Twenty age- and sex-matched patients who were not atopic were included as controls. An allergic rhinitis diagnosis was made according to the Allergic Rhinitis and its Impact on Asthma document. Complete history taking, physical examination, skin-prick test, complete blood cell count, erythrocyte sedimentation rate, total serum immunoglobulin E (IgE), IDO concentration, and nasal smear for eosinophils were done for the patients.
  
  
  RESULTS
  There was a significant increase in IDO levels in allergic rhinitis in comparison with subjects without allergy (p < 0.001). IDO was positively correlated with total IgE levels (p < 0.037). There was an insignificant relationship among IDO levels and age, sex, duration of the disease, severity score, nasal and blood eosinophilia, and number of positive allergens.
  
  
  CONCLUSIONS
  IDO plays an important role in patients with atopic symptomatic allergic rhinitis, especially with increased levels of IgE. There is no relationship between IDO levels and severity of disease.
authors.affiliation: Department of Internal Medicine, Allergy and Clinical Inmmunology, Ain Shams University, Cairo, Egypt.
authors.forename: Maged Mohamed
authors.initials: MM
authors.lastname: Refaat
authors.forename: Asmaa Saber Mostafa
authors.initials: AS
authors.lastname: Abdel Rehim
authors.forename: Hoda Mohammed
authors.initials: HM
authors.lastname: El-Sayed
authors.forename: Nesrine Aly
authors.initials: NA
authors.lastname: Mohamed
authors.forename: Ahmed Gamal
authors.initials: AG
authors.lastname: Khafagy
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D018450:Disease Progression; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007111:Immunity, Cellular; D007073:Immunoglobulin E / Q000097:blood; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase / Q000097:blood*; D008297:Male; D065631:Rhinitis, Allergic / Q000201:enzymology* / Q000276:immunology; D012882:Skin Tests; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*
chemical_list: D015415:Biomarkers; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase; D007073:Immunoglobulin E