Fig. 1. The innate antimicrobial defense mechanisms of neutrophils.

Neutrophils mediate antimicrobial defense primarily through three major mechanisms: phagocytosis, degranulation, and the formation of neutrophil extracellular traps (NETs). Phagocytosis is triggered through a variety of cell surface receptors (major receptors indicated). Neutrophils also secrete a variety of enzymes and antimicrobial components, including those found in their granules (major types of neutrophil granules and contents are indicated). Finally, diverse stimuli (indicated) can activate intracellular pathways that mediate the formation and release of NETs.