Neutrophil-Derived Proteins: Selling Cytokines by the Pound

Publisher Summary This chapter summarizes the recent knowledge on the production of cytokines by neutrophils in vitro and in vivo—particularly molecular regulation and other biological and pathophysiological aspects. Neutrophils act as the first line of defense against invading bacteria and other microorganisms. Traditionally, mature neutrophils are considered as differentiated cells lacking the ability to synthesize proteins. In recent years, however, it has become increasingly clear that this view is outdated. Studies conducted in a large number of laboratories have shown that neutrophils not only synthesize numerous proteins that directly participate in their effector functions but also produce a variety of pro- and anti-inflammatory polypeptides. The classic role attributed to neutrophils is still based on the obsolete view that polymorphonuclear neutrophil granulocytes (PMNs) are terminally differentiated, short-lived cells with minimal transcriptional or translational activity. The chapter discusses the ability of neutrophils to synthesize and release various cytokines. Moreover, the fact that neutrophils clearly predominate over other cell types under various in vivo conditions suggests that—at least under some circumstances—the contribution of PMN-derived cytokines can be of foremost importance. In this respect, there already exists evidence that suggests that under some circumstances, the contribution of PMN-derived cytokines can be of foremost importance to the evolution of certain pathologies.