Activation of CD8+ T lymphocytes with anti-CD3 and anti-CD28 antibodies. The activation status was detected by double-staining for the activation markers CD25 and CD45R0. (A) Flow-cytometrical analysis of CD8+ T lymphocytes activated in the presence of neurotransmitters (10 μM norepinephrine, 1 μM substance P and dopamine). The graph shows the mean values and standard deviation of double-positive T lymphocytes of four independent experiments with cells from different donors. Asterisks mark statistically significant changes (p < 0.05). Stepwise addition of external IL-2 reverses the inhibitory effect of the neurotransmitters, but in turn leads to a higher number of CD25+ CD45RO+ lymphocytes. (B) Expression of IL-2 RNA during activation under the influence of neurotransmitters. RT-PCR was performed with cDNA in the dilution steps 1:125 1:625 1:3125 and 1: 15625. Per lane, 10 μl of PCR sample were applied to the agarose gel. Beta-actin expression was used as house-keeping gene. (C) The release of IL-2 by CD8+ lympocytes during activation in the presence of neurotransmitters was measured by using an enzyme-linked immunoassay. The graph shows mean values and standard deviation of three independent experiments with cells from different donors.