Intracellular IL-6 protein in PMNs after in vitro rhG-CSF stimulation. Flow cytometric histograms depict staining of freshly isolated PMNs from a normal donor and after incubation with 10 ng/mL rhG-CSF for up to 24 hours. Results presented are from one of four similar experiments. With each time point, simultaneous controls were evaluated and these showed no difference from baseline isotype staining (not shown).