title: Effects of helium and air inhalation on the innate and early adaptive immune system in healthy volunteers ex vivo.
abstract: BACKGROUND
  Helium inhalation protects myocardium, brain and endothelium against ischemia/reperfusion injury in animals and humans, when applied according to specific "conditioning" protocols. Before widespread use of this "conditioning" agent in clinical practice, negative side effects have to be ruled out. We investigated the effect of prolonged helium inhalation on the responsiveness of the human immune response in whole blood ex vivo.
  
  
  METHODS
  Male healthy volunteers inhaled 30 minutes heliox (79%He/21%O(2)) or air in a cross over design, with two weeks between measurements. Blood was withdrawn at T0 (baseline), T1 (25 min inhalation) and T2-T5 (1, 2, 6, 24 h after inhalation) and incubated with lipopolysaccharide (LPS), lipoteichoic acid (LTA), T-cell stimuli anti-CD3/ anti-CD28 (TCS) or RPMI (as control) for 2, 4 and 24 hours or not incubated (0 h). An additional group of six volunteers inhaled 60 minutes of heliox or air, followed by blood incubation with LPS and RPMI. Tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), interferon-γ (IFN-γ) and interleukin-2 (IL-2) was analyzed by cytometric bead array. Statistical analysis was performed by the Wilcoxon test for matched samples.
  
  
  RESULTS
  Incubation with LPS, LTA or TCS significantly increased TNF-α, IL-1β, IL-6, IL-8, IFN-γ and IL-2 in comparison to incubation with RPMI alone. Thirty min of helium inhalation did not influence the amounts of TNF-α, IL-1β, IL-6, IL-8, IFN-γ and IL-2 in comparison to air. Sixty min of helium inhalation did not affect cytokine production after LPS stimulation.
  
  
  CONCLUSIONS
  We conclude that 79% helium inhalation does not affect the responsiveness of the human immune system in healthy volunteers.
  
  
  BACKGROUND
  Dutch Trial Register: http://www.trialregister.nl/ NTR2152.
authors.affiliation: Laboratory of Experimental Intensive Care and Anesthesiology, Academic Medical Centre, University of Amsterdam, The Netherlands.
authors.forename: Gezina T M L
authors.initials: GT
authors.lastname: Oei
authors.forename: Kirsten F
authors.initials: KF
authors.lastname: Smit
authors.forename: Djai
authors.initials: D
authors.lastname: vd Vondervoort
authors.forename: Daniel
authors.initials: D
authors.lastname: Brevoord
authors.forename: Arjan
authors.initials: A
authors.lastname: Hoogendijk
authors.forename: Catharina W
authors.initials: CW
authors.lastname: Wieland
authors.forename: Markus W
authors.initials: MW
authors.lastname: Hollmann
authors.forename: Benedikt
authors.initials: B
authors.lastname: Preckel
authors.forename: Nina C
authors.initials: NC
authors.lastname: Weber
mesh_terms: D000388:Air; D016207:Cytokines / Q000378:metabolism; D006371:Helium / Q000008:administration & dosage*; D006801:Humans; D007113:Immunity, Innate; D019570:Inhalation Exposure; D008297:Male; D012016:Reference Values
chemical_list: D016207:Cytokines; D006371:Helium