title: Circulating myeloid and plasmacytoid dendritic cells after allergen inhalation in asthmatic subjects.
abstract: BACKGROUND
  Dendritic cells are key contributors to initiation and maintenance of T-cell immunity to inhaled allergen. The purpose of this study was to enumerate the changes in peripheral blood myeloid (mDCs) and plasmacytoid dendritic cells (pDCs), the DCs expressing chemokine receptor 6 (CCR6) and chemokine receptor 7 (CCR7), following diluent and allergen inhalation in asthmatic subjects.
  
  
  METHODS
  Peripheral blood was obtained from 16 allergic asthmatic subjects before and at 0.5, 1, 2, 3, 4, 6, 24, and 48 h after inhaled diluent and allergen challenges. Dendritic cells were enumerated using flow cytometry.
  
  
  RESULTS
  Allergen inhalation significantly reduced mDCs at 6 h (21.3 +/- 2.0 vs 15.0 +/- 1.8/microl blood; P < 0.05) and 24 h (21.5 +/- 3.4 vs 16.4 +/- 2.4/microl blood; P < 0.05) after challenge. Circulating pDCs were significantly lower than baseline up to 24 h after both allergen and diluent challenges. There was a significant efflux of CCR6(+) mDCs from peripheral blood at 6 h and CCR6(+) pDCs at 4 h after allergen challenge, when compared with diluent. There was no difference in the number of circulating CCR7(+) mDCs or pDCs after diluent or allergen challenges.
  
  
  CONCLUSIONS
  Peripheral blood mDCs and CCR6(+) mDCs, but not pDCs, are reduced up to 24 h after allergen inhalation. Thus, allergen inhalation causes trafficking of immature CCR6(+) DCs from blood into the airway, while that of the trafficking of the mature CCR7(+) DCs from the airways into the regional lymph nodes probably occurs through the lymphatic system.
authors.affiliation: Department of Medicine, McMaster University, Hamilton, ON, Canada.
authors.forename: E
authors.initials: E
authors.lastname: Farrell
authors.forename: T M
authors.initials: TM
authors.lastname: O'Connor
authors.forename: M
authors.initials: M
authors.lastname: Duong
authors.forename: R M
authors.initials: RM
authors.lastname: Watson
authors.forename: T
authors.initials: T
authors.lastname: Strinich
authors.forename: G M
authors.initials: GM
authors.lastname: Gauvreau
authors.forename: P M
authors.initials: PM
authors.lastname: O'Byrne
mesh_terms: D000293:Adolescent; D000328:Adult; D000485:Allergens; D000818:Animals; D001249:Asthma / Q000097:blood* / Q000139:chemically induced / Q000276:immunology*; D001985:Bronchial Provocation Tests / Q000009:adverse effects; D003713:Dendritic Cells / Q000276:immunology*; D005434:Flow Cytometry; D006801:Humans; D007962:Leukocytes / Q000187:drug effects / Q000378:metabolism; D018655:Lymphocyte Count; D008875:Middle Aged; D022423:Myeloid Cells / Q000276:immunology*; D021381:Protein Transport; D054399:Receptors, CCR6 / Q000097:blood; D054400:Receptors, CCR7 / Q000097:blood
chemical_list: D000485:Allergens; D054399:Receptors, CCR6; D054400:Receptors, CCR7