The goal of this experiment is to determine the
effect of microgravity on both the ability of adherent monocytes to
migrate on a surface (Motion), as well as to interact with T-cells
(Interact). Monocyte locomotion is important in immune function, since
monocytes need to bind to tissue surfaces and then migrate through
them. Additionally, interaction of monocytes with T-lymphocytes is
important for the co-stimulatory signal (2nd signal).
The experiment consists of two components: In the “Motion” experiment
a monocyte cell line will be incubated on a colloid gold
substrate. As the monocytes migrate they remove the colloid gold, leaving
a track on the substrate which records the cell motion. The experiment
will be terminated in-flight by addition of formaldehyde fixative. The
“Interact” experiment will mix T-cell and monocyte cells and samples
will be fixed at two time intervals. Post-flight, the clustering of
T-cells with monocytes as well as the distribution of adhesion receptors
on each cell type will be observed by microscopy.