title: Adrenocortical and immune responses following short- and long-duration spaceflight.
abstract: BACKGROUND
  Short-term spaceflight is associated with significant but reversible immunological alterations. However, little information exists on the effects of long-duration spaceflight on neuroimmune responses.
  
  
  METHODS
  We collected multiple pre- and postflight samples from Shuttle and International Space Station (ISS) crewmembers in order to compare adrenocortical and immune responses between short- (approximately 11 d) and long-duration (approximately 180 d) spaceflight.
  
  
  RESULTS
  In Shuttle crewmembers, increased stress hormone levels and altered leukocyte subsets were observed prior to launch and at landing. Additionally, typical stress-induced shifts in leukocyte and lymphocyte subsets, as well as the percentage of T-cells capable of producing intracellular IFN-gamma were also decreased just before launch and immediately after landing. Plasma IL-10 levels were increased before launch but not postflight. No preflight changes occurred in ISS crewmembers, but long-duration crewmembers exhibited significantly greater spikes in both plasma and urinary cortisol at landing as compared to Shuttle crewmembers. The percentage of T-cells capable of producing intracellular IFN-gamma was decreased in ISS crewmembers. Plasma IL-10 was increased postflight. Unexpectedly, stress-induced shifts in lymphocyte subpopulations were absent after long-duration flights despite significantly increased stress hormones at landing.
  
  
  CONCLUSIONS
  Our results demonstrate significant differences in neuroimmune responses between astronauts flying on short-duration Shuttle missions versus long-duration ISS missions, and they agree with prior studies demonstrating the importance of mission duration in the magnitude of these changes.
authors.affiliation: Microgen Laboratories, La Marque, TX 77568, USA. rpstowe@microgenlabs.com
authors.forename: Raymond P
authors.initials: RP
authors.lastname: Stowe
authors.forename: Clarence F
authors.initials: CF
authors.lastname: Sams
authors.forename: Duane L
authors.initials: DL
authors.lastname: Pierson
mesh_terms: D018480:Astronauts; D015415:Biomarkers / Q000097:blood / Q000652:urine; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000097:blood / Q000652:urine; D007107:Immune System / Q000503:physiopathology*; D007371:Interferon-gamma / Q000276:immunology; D016753:Interleukin-10 / Q000097:blood; D008297:Male; D008875:Middle Aged; D009490:Neurosecretory Systems / Q000503:physiopathology*; D013026:Space Flight; D016176:T-Lymphocyte Subsets / Q000276:immunology; D013997:Time Factors; D014893:Weightlessness
chemical_list: D015415:Biomarkers; D016753:Interleukin-10; D007371:Interferon-gamma; D006854:Hydrocortisone