Isolation of human and mouse neutrophils ex vivo and in vitro

Neutrophils are one of main cellular elements of innate immune system that act as the first line of host defense against invasion by microorganisms. Neutrophils phagocytose and kill microbes through production of toxins such as hydrogen peroxide, superoxide anion, and nitric oxide. Recent studies have demonstrated a new strategy-so-called neutrophil extracellular traps (NETs) that are able to kill bacteria and fungi in vivo and in vitro (Brinkmann et al., Science 303:1532-1535, 2004; Wartha and Henriques-Normark, Sci Signal 1:pe25, 2008). Neutrophils are, therefore, always a major focus of investigation for scientists all over the world. Isolation of neutrophils from either human beings or animals such as mice is a very common first step for researchers to start their investigations on innate immunity to microbes. Fortunately, there are nowadays many methods available to obtain neutrophils from peripheral blood, bone marrow, and cell cultures. However, researchers still encounter technical problems in terms of purification, viability, and recovery. In this chapter, different approaches to the methodology of the isolation of neutrophils are described.