Human Neutrophil Priming is Required for their Activation by the Extracellular DNA
The extracellular plasma DNA is thought to act as a damage-associated molecular pattern causing immune cells activation. However, purified preparations of mitochondrial and nuclear DNA were unable to induce neutrophil activation in vitro. We aimed at the examination whether GM-CSF acting as a neutrophil priming agent, may promote the activation of neutrophils by different types of extracellular DNA. GM-CSF pretreatment greatly increased p38 MAPK phosphorylation and promoted CD11b/CD66b expression in human neutrophils treated by mitochondrial and, to a lesser extent, by nuclear DNA. Our experiments clearly indicated that GM-CSF-induced priming of the human neutrophils is necessary for their subsequent activation by extracellular DNA.