Neutrophil Function and Response

Neutrophils are the major pathogen-fighting innate immune cells recruited to sites of infection/inflammation to recognize, phagocytose, and kill pathogens through cytotoxic mechanisms, including production of reactive oxygen species (ROS), release of antimicrobial peptides, and expulsion of nuclear contents to form neutrophil extracellular traps (NETs). This chapter reviews neutrophil function and the role of neutrophils in adaptive immunity, inflammation, and tissue injury. Rolling of neutrophils on the endothelium is mediated by selectins, which are type I integral membrane proteins that recognize specific glycan structures. After neutrophil entry into the tissues, neutrophil activation allows for rapid acquisition of phagocytic functions, ROS generation, release of granule proteins, and production of NETs. Intracellular antimicrobial mechanisms within the neutrophil phagosome have generally been divided into oxygen-dependent and oxygen-independent mechanisms, but it is now known that these mechanisms are complexly integrated.