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Lymphocyte Functions in MicrogravityTo understand the mechanism of immunity impairment in space it is important to analyze the direct effects of space-related conditions on different lymphocytes functions. Since 1992, we are investigating the effect of modeled and true microgravity (MG) on numerous lymphocyte functions. We had shown that modeled (MMG) and true microgravity inhibit lymphocyte locomotion through type I collagen. Modeled microgravity also suppresses polyclonal and antigen-specific lymphocyte activation. Polyclonal activation of lymphocytes prior to exposure to MMG abrogates the MG-induced inhibition of lymphocyte locomotion. The relationship between activation deficits and the loss of locomotion in MG was investigated using PKC activation by phorbol ester (PMA) and calcium ionophore (ionomycin). Direct activation of PKC by PMA substantially restored the MMG-inhibited lymphocyte locomotion and PHA-induced lymphocyte activation lonomycin by itself did not restore either locomotion or activation of the lymphocytes, indicating that these changes are not related to the impairment in the calcium flux in MMG. Treatment of lymphocytes with PMA before exposure to MMG prevented the loss of locomotion. It was observed that DNA synthesis is not necessary for restoration of locomotion since mitomicin C treated and untreated cells recovered their locomotion to the same level after PKC activation. Our recent data indicate that microgravity may selectively effect the expression of novel Ca2+ independent isoforms of PKC, in particularly PKC sigma and delta. This provides a new insight in understanding of the mechanisms of MG-sensitive cellular functions.
Document ID
20000116331
Acquisition Source
Johnson Space Center
Document Type
Preprint (Draft being sent to journal)
Authors
Pellis, Neal R.
(NASA Johnson Space Center Houston, TX United States)
Risin, Diane
(Wyle Labs., Inc. Houston, TX United States)
Sundaresan, A.
(Wyle Labs., Inc. Houston, TX United States)
Cooper, D.
(La Jolla Inst. CA United States)
Dawson, David L.
Date Acquired
August 19, 2013
Publication Date
January 1, 1999
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: NRA-OLMSA-02/NSCORT
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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