Immune dysfunction has been demonstrated to occur during space flight, and in certain ground-based models of space flight. Immune dysregulation, in conjunction with high-energy radiation exposure and latent viral reactivation, may have important health consequences during exploration class space flights. The assays developed for the Immune SMO will be evaluated for the routine monitoring of space-related immune alterations. It is important to develop a monitoring strategy (none currently exists) prior to the evaluation of potential countermeasures. This panel of assays may have potential terrestrial applications for the monitoring of immune function in populations with altered immunity (ranging from high stress individuals to third world medicine).
Additional objectives are to examine the detectable immune system changes associated with the inflight period, distinct from post-landing assessments. Specifically, this study will determine the scope of clinical changes associated with space flight by assessing: leukocyte subset distribution; cytokine profile changes (RNA, intracellular, secreted), viral reactivation (viral specific T cell number and function, viral antibody levels, viral DNA detection), and physiological stress hormone levels.
Short-duration subjects provided a liquid saliva sample every other day for the duration of the mission such that the final sample was collected on R-1. Short-duration crewmembers also collected dry book saliva samples on FD2 and on R-1. One blood sample was collected on R-1 in conjunction with the final liquid saliva sample and second dry book saliva sample. Long-duration subjects performed three sessions inflight: early, mid, and late increment. Each session consisted of four liquid saliva collections (performed every other day), with a blood draw and dry book saliva sample collection occurring on the last day of the liquid saliva collections. For the late increment session, the final liquid saliva sample, the blood draw and dry book saliva sample collection occurred on R-1. For both long and short-duration crewmembers, there wasn’t any in flight urine collection.
Most bulk leukocyte subsets (WBC, differential, lymphocyte subsets) were unaltered during space flight, but were altered following landing. CD8+ T cell subsets, including cytotoxic, central memory and senescent were altered during spaceflight. T cell early blastogenesis varied by culture mitogen. Functional responses to staphylococcal enterotoxin were reduced during and following spaceflight, whereas response to anti-CD3/28 antibodies was elevated post-flight. The level of virus specific T cells were generally unaltered, however virus specific T cell function was depressed both during and following flight. Plasma levels of IFNa, IFN?, IL-1ß, IL-4, IL-10, IL-12, and TNFa were significantly elevated in-flight, while IL-6 was significantly elevated at R?+?0. Cytokine production profiles following mitogenic stimulation were significantly altered both during, and following spaceflight. Specifically, production of IFN?, IL-17 and IL-10 were reduced, but production of TNFa and IL-8 were elevated during space flight.
This study indicates that specific parameters among leukocyte distribution, T cell function and cytokine production profiles are altered during flight. These findings distinguish in-flight dysregulation from stress-related alterations observed immediately following landing.
|Mission||Launch/Start Date||Landing/End Date||Duration|
|Expedition 16||10/10/2007||04/19/2008||192 days|
|Expedition 17||04/08/2008||10/23/2008||198 days|
|Expedition 18||10/12/2008||04/17/2009||187 days|
|Expedition 19||03/26/2009||10/11/2009||199 days|
|Expedition 20||05/27/2009||10/11/2009||137 days|
|Expedition 21||10/11/2009||12/01/2009||51 days|
|Expedition 22||11/30/2009||03/18/2010||109 days|
|Expedition 23||03/18/2010||06/01/2010||75 days|
|Expedition 24||06/01/2010||09/25/2010||117 days|
|Expedition 25||09/24/2010||11/25/2010||31 days|
|Expedition 26||11/26/2010||03/16/2011||111 days|
|Expedition 27||03/14/2011||05/23/2011||70 days|
|Expedition 28||05/23/2011||09/15/2011||115 days|
|Expedition 29||09/16/2011||11/21/2011||40 days|
|Expedition 30||11/14/2011||04/27/2012||166 days|
|Expedition 31||04/27/2012||07/01/2012||65 days|