Assessment of priming of the human neutrophil respiratory burst

Abstract

Neutrophils play an essential role in host defense against microbial pathogens and in the infl ammatory reaction. Upon activation, neutrophils produce reactive oxygen species (ROS) such as superoxide anion (O 2•- ), hydrogen peroxide (H2 O2 ), and hypochlorous acid (HOCl), a process referred to as the respiratory burst. The enzyme responsible for this process is called the NADPH oxidase or respiratory burst oxidase. This multicomponent enzyme system is composed of two transmembrane proteins (p22phox and gp91phox/NOX2, which form the cytochrome b 558 ), three cytosolic proteins (p47phox, p67 phox, p40phox), and a GTPase (Rac1 or Rac2), which assemble at membrane sites upon cell activation. The NADPH oxidase is in a resting state in circulating neutrophils, and its activation can be induced by a large number of soluble and particulate agents such as the formylated peptide, formyl-methionyl-leucyl-phenylalanine (fMLF). This activation can be enhanced or "primed" by pro-infl ammatory cytokines, LPS and other agents. Priming is a "double-edged sword" process as it contributes to a rapid and effi cient elimination of the pathogens but can also induce the generation of large quantities of toxic ROS that can damage surrounding tissues and participate to infl ammation. In this chapter, we describe the techniques used to measure priming of the NADPH oxidase in human neutrophils. © 2014 Springer Science+Business Media, LLC.