Abstract
Neutrophils are innate immune cells that play important roles in many physiological and pathological processes, including immune defense and cancer metastasis. In addition to the release of proinflammatory cytokines, chemokines, and cytoplasmic granules containing digestive proteins, in recent years, neutrophils have been observed to release neutrophil extracellular traps (NETs) that consist of extracellular DNA associated with antimicrobial proteins, such as histones and myeloperoxidase. These NETs are increasingly being recognized as an important mechanism of neutrophil host defense and function. This chapter will summarize the current literature on the known processes of NET formation and describe in detail an immunofluorescence approach that can be employed to visualize and quantify NETs in vitro.