Early NASA studies demonstrated that the lymphocytes (white blood cells) had a blunted response to mitogen stimulation of growth. In the late 60’s returning Apollo astronauts were found to have reduced immune function after spaceflight, taking approximately 7 days to recover normal function. As seen in the figure below, T-cells in astronauts exposed to microgravity did not respond to mitogen, while cells belonging to non-flown astronaut backups had normal response.
Later, Dr. Augusto Cogoli demonstrated that indeed the cells themselves were responsible for the change, it was not a systemic change. Dr. Cogoli demonstrated changes in the T-cells during exposure to microgravity. This current program will examine the expression of IL-2, and the three IL-2 receptor subunits (alpha, beta and gamma) in microgravity with and without an artificial 1g gravity vector and compare those results with ground controls. These studies will show the regulation of the earliest signals that cause the T-cell to activate and the role of normal earth’s gravity in that signaling.
Considering that all Earth's life evolved in 1 gravity, it would follow that some processes might differ in the absence of gravity. The stages of T-cell activation are shown to the right.
The first steps include antigen binding and secondary recognition signals. Third step is secretion of IL-2. Fourthly, is the synthesis of the three IL-2 receptors and finally the binding of IL-2 to its receptor. These are the steps of activation that will be analyzed using RTPCR for messenger RNA and with western blots for changes in protein synthesis.
This laboratory has become interested in the signal pathways that are stimulated early in activation. These include extracellular and intercellular mechanisms. Since all terrestrial life began in a gravity field.
The possible pathways involved in early T-cell activation are shown below. This study of alterations of early T-cell activation microgravity gives us the unique opportunity to examine the role of Earth’s gravity in immune function.