WBC, parameters and defense signaling capacity may also have an impact on overall crew
member immune system health. ISS crew members, by contrast, did not show increased
cortisol stress hormone levels at any time prior to launch. A plausible explanation is the
training, which differs greatly for these astronauts who are prepared mentally for long-duration
flights that are psychologically challenging, is much longer and diverse than shuttle astronauts.
Stress hormones returned to preflight levels for both groups after a few days back on earth.
Also, approximately 50% of the subjects had very high WBC counts, which have typically been
associated with increased stress hormones, at landing. Unexpectedly, some subsets of white
blood cells did not show normal response to the rise in stress hormones for long-duration crew
members. Further study is needed to determine if this is a failure of these WBCs to properly
respond to acute stress or if the blood production process is altered during long-duration
spaceflight. The authors conclude the current ISS training successfully reduces stress and
interventions employed during this period in which astronauts are most accessible would likely
produce the desired effects. These results agree with prior studies demonstrating the
significance of mission duration in the magnitude of these immune system changes.
PUBLICATION(S)
Crucian BE, Stowe RP, Mehta SK, Quiriarte HD, Pierson DL, Sams CF. Alterations in adaptive
immunity persist during long-duration spaceflight. npj Microgravity. September 3,
2015;1:15013. doi: 10.1038/npjmgrav.2015.13.
Mehta SK, Laudenslager ML, Stowe RP, Crucian BE, Sams CF, Pierson DL. Multiple latent viruses
reactivate in astronauts during Space Shuttle missions. Brain, Behavior, and Immunity.
October 2014; 41:210-217. doi: 10.1016/j.bbi.2014.05.014.
Crucian BE, Zwart SR, Mehta SK, et al. Plasma cytokine concentrations indicate that in vivo
hormonal regulation of immunity is altered during long-duration spaceflight. Journal of
Interferon and Cytokine Research. October 2, 2014;34: 778 -786. doi: 10.1089/jir.2013.0129.
Crucian BE, Stowe RP, Mehta SK, et al. Immune system dysregulation occurs during short
duration spaceflight on board the space shuttle. Journal of Clinical Immunology. February
2013;33(2):456-465. doi: 10.1007/s10875- 012 -9824-7.
Crucian BE, Stowe RP, Quiriarte HD, Pierson DL, Sams CF. Monocyte Phenotype and Cytokine
Production profiles are dysregulated by short-duration spaceflight. Aviation, Space, and
Environmental Medicine. 2011;82(9):857-862. doi: 10.3357/ASEM.3047.2011.
Kaur I, Simons ER, Kapadia AS, Ott CM, Pierson DL. Effect of spaceflight on ability of monocytes
to respond to endotoxins of gram-negative bacteria. Clinical and Vaccine Immunology. October
2008;15(10):1523- 15 28. doi: 10.1128/CVI.00065-08.
Kaur I, Simons ER, Castro VA, Ott CM, Pierson DL. Changes in monocyte functions of astronauts.
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