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T Cell Activation Thresholds are Affected by GravitationalT cells stimulated in space flight by various mitogenic signals show a dramatic reduction in proliferation and expression of early activation markers. Similar results are also obtained in a ground based model of microgravity, clinorotation, which provides a vector-averaged reduction of the apparent gravity on cells without significant shear force. Here we demonstrate that T cell inhibition is due to an increase in the required threshold for activation. Dose response curves indicate that cells activated during clinorotation require higher stimulation to achieve the same level of activation, as measured by CD69 expression. Interleukin 2 receptor expression, and DNA synthesis. The amount of stimulation necessary for 50% activation is 5 fold in the clinostat relative to static. Correlation of TCR internalization with activation also exhibit a dramatic right shift in clinorotation, demonstrating unequivocally that signal transduction mechanism independent of TCR triggering account for the increased activation threshold. Previous results from space flight experiments are consistent with the dose response curves obtained for clinorotation. Activation thresholds are important aspects of T cell memory, autoimmunity and tolerance Clinorotation is a useful, noninvasive tool for the study of cellular and biochemical event regulating T cell activation threshold and the effects of gravitation forces on these systems.
Document ID
20000101070
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Adams, Charley
(NASA Johnson Space Center Houston, TX United States)
Gonzalez, M.
(NASA Johnson Space Center Houston, TX United States)
Nelman-Gonzalez, M.
(NASA Johnson Space Center Houston, TX United States)
Date Acquired
August 19, 2013
Publication Date
January 1, 1999
Subject Category
Life Sciences (General)
Meeting Information
Meeting: 28th Annual Autumn Immunology Conference
Location: Chicago, IL
Country: United States
Start Date: November 19, 1999
End Date: November 21, 1999
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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