Purpose of review: Neutrophils priming has been long studied in vitro. Recent studies describe it in vivo. In pathophysiological conditions, complex, heterogeneous characteristics of priming are described in the last few years.
Recent findings: Priming can occur systemically when insults such as sepsis or trauma result in an array of circulating mediators and circulating primed neutrophils seem to exert detrimental effects either directly, or indirectly by interacting with other cells, thereby contributing to the development of organ dysfunction. Local priming of neutrophils augments their ability to clear infection, but may also lead to local bystander tissue injury, for example, in the inflamed joint. The complexity, heterogeneity and dynamic nature of inflammatory responses and the accessibility of cells from local sites make neutrophil priming challenging to study in human disease; however, recent advances have made significant progress to this field.
Summary: Herein, we summarize the literature regarding neutrophil priming in selected conditions. In some diseases and in the setting of specific genetic influences, the priming repertoire seems to be restricted, with only some neutrophil functions upregulated. A greater understanding of the nature of neutrophil priming and its role in human disease is required before this process becomes tractable to therapeutic intervention.