Interaction of CD8+ T lymphocytes with endothelial cells in a flow-through extravasation assay. The left columns of each graph show the adhesion and rolling of non-activated cells, the right columns show the adhesion and rolling of activated cells. "Adhesion" is the total number of tightly adherent cells in a 20 minute observation period. "Rolling" is the number of cells per minute, which rolled on the endothelium before they either tightly adhered or were washed away. Graphs show mean values and standard deviation of three independent experiments for each neurotransmitter: (A) 10 μM norepinephrine, (B) 1 μM dopamine, and (C) 1 μM substance P. Asterisks mark statistically significant changes (p < 0.05).