title: Hypobaric hypoxia in 3000 m altitude leads to a significant decrease in circulating plasmacytoid dendritic cells in humans.
abstract: BACKGROUND
  Hypoxia is known to affect the immune system. It leads to an increase in pro-inflammatory cytokines such as interleukin-6 and influences the number of different inflammatory cells. This study investigates the effect of hypoxia on the number of different subsets of circulating human dendritic cells (DCs) as professional antigen-presenting cells.
  
  
  METHODS
  The number of circulating DCs was determined via Fluorescence activated cell sorting analysis in peripheral blood of 17 healthy volunteers (age 35.9±2.6 years) in normoxia (baseline, BL), hypoxia (altitude 3000 m, alpine passive escalation), and again normoxia (follow-up, FU).
  
  
  RESULTS
  Exposure to hypobaric hypoxia in high altitude, 3000 m, led to a significant decrease in the participants' oxygen saturation, and an increase in the breathing frequency whereas blood pressure and heart rate were not significantly altered. FACS analysis revealed a significant hypoxia induced decrease in circulating plasmacytoid (p) DCs compared to baseline levels (BL: 0.10 [0.08-0.18] % of white blood cell count (WBC), 3000 m: 0.03 [0.02-0.06] % WBC, p < 0.001). During follow up, again a significant reconstitution of circulating pDCs was observed (FU: 0.16±[0.11-0.26] % WBC, p = 0.0013).
  
  
  CONCLUSIONS
  Hypobaric hypoxia caused by exposure to altitude results in a significant reduction in the number of circulating pDCs.
authors.forename: Ilonka
authors.initials: I
authors.lastname: Rohm
authors.forename: Nicole
authors.initials: N
authors.lastname: Aderhold
authors.forename: Josephine
authors.initials: J
authors.lastname: Ratka
authors.forename: Bjoern
authors.initials: B
authors.lastname: Goebel
authors.forename: Marcus
authors.initials: M
authors.lastname: Franz
authors.forename: Rudin
authors.initials: R
authors.lastname: Pistulli
authors.forename: Thomas
authors.initials: T
authors.lastname: Gecks
authors.forename: Hans Reiner
authors.initials: HR
authors.lastname: Figulla
authors.forename: Atilla
authors.initials: A
authors.lastname: Yilmaz
authors.forename: Christian
authors.initials: C
authors.lastname: Jung
mesh_terms: D000328:Adult; D000531:Altitude; D015687:Cell Hypoxia; D003713:Dendritic Cells / Q000378:metabolism*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007249:Inflammation; D008297:Male
keywords: Dendritic cells; altitude; hypobaric hypoxia; inflammation