Transient immune impairment after a simulated long-haul flight

Aviat Space Environ Med. 2012 Apr;83(4):418-23. doi: 10.3357/asem.3162.2012.


Introduction: Almost 2 billion people travel aboard commercial airlines every year, with about 20% developing symptoms of the common cold within 1 wk after air travel. We hypothesize that hypobaric hypoxic conditions associated with air travel may contribute to immune impairment.

Methods: We studied the effects of hypobaric hypoxic conditions during a simulated flight at 8000 ft (2438 m) cruising altitude on immune and stress markers in 52 healthy volunteers (mean age 31) before and on days 1, 4, and 7 after the flight. We did a cohort study using a generalized estimating equation to examine the differences in the repeated measures.

Results: Our findings show that the hypobaric hypoxic conditions of a 10-h overnight simulation flight are not associated with severe immune impairment or abnormal IgA or cortisol levels, but with transient impairment in some parameters: we observed a transient decrease in lymphocyte proliferative responses combined with an upregulation in CD69 and CD14 cells and a decrease in HLA-DR in the immediate days following the simulated flight that normalized by day 7 in most instances.

Discussion: These transient immune changes may contribute to an increased susceptibility to respiratory infections commonly seen after long-haul flights.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aircraft*
  • Altitude*
  • Antigens, CD / analysis
  • Atmosphere Exposure Chambers
  • Biomarkers / analysis
  • Blood Cell Count
  • Female
  • Flow Cytometry
  • HLA-DR Antigens / analysis
  • Humans
  • Hydrocortisone / analysis
  • Hypoxia / immunology*
  • Immunoglobulin A / analysis
  • Male
  • Middle Aged


  • Antigens, CD
  • Biomarkers
  • HLA-DR Antigens
  • Immunoglobulin A
  • Hydrocortisone