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Lymphocyte Functions in Space - Related ConditionsOur previous studies showed that modeled (MMG) and true (STS-54 and STS-56) microgravity (MG) inhibit human lymphocyte locomotion. MMG also suppresses polyclonal and antigen-specific lymphocyte activation. Analysis of the relationship between activation deficits and the loss of locomotion in MG suggested a fundamental defect in signal transduction mechanism localized either at the PKC level or upstream at the cell membrane. FACS analysis of the expression of PKC isoforms in PBMC revealed that MMG selectively inhibits the PKC isoforms expression. The decrease was most prominent in PKC epsilon, less obvious in PKC delta and almost marginal and insignificant in PKC alpha. Western blot analysis confirmed these results (PKC epsilon protein expression was downregulated at 24, 72 and 96 hours in MG). We also found a decrease in PKC epsilon mRNA expression. MMG inhibited programmed cell death (PCD) in lymphocytes. Inhibition was observed in two types of experiments: 1) when PCD was induced by gamma-radiation of PBMC, and 2) when PCD in activated T cells was triggered by PHA-M or PMA + ionomycin restimulation. The established direct effects of MG on signal transduction mechanisms as well as on PCD in lymphocytes could contribute to the impairment of the immunity in space.
Document ID
20000083358
Acquisition Source
Johnson Space Center
Document Type
Preprint (Draft being sent to journal)
Authors
Risin, D.
(Wyle Labs., Inc. Houston, TX United States)
Sundaresan, A.
(Wyle Labs., Inc. Houston, TX United States)
Pellis, N. R.
(NASA Johnson Space Center Houston, TX United States)
Davson, David L.
Date Acquired
August 19, 2013
Publication Date
January 1, 1999
Subject Category
Life Sciences (General)
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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