Phagocytosis and destruction of inflammatory agents
Phagocytosis
We'll use neutrophil destruction of microbes as an example.
1. Neutrophil recognition of the microbe via sensors.
2. The neutrophil engulfs the microbe and moves it into a phagosome.
3. Lysosomes merge with the phagosome, which exposes the microbe to lysosomal degradative enzymes in a phagolysosome.
4. Lysosomal enzymes, reactive oxygen species (ROS, aka, reactive oxygen intermediates), and inducible nitric oxide (iNO) destroy the microbe.
– Inflammatory cytokines, such as interferon gamma, trigger the production of ROS and iNO within the lysosomes and phagolysosomes.
NETs
In addition to phagocytosis, neutrophils can produce extracellular traps (aka, NETs) to destroy infective pathogens.
In this process, the neutrophil exudes its nuclear materials to envelop the microbes in chromatin and concentrated antimicrobial peptides and enzymes.
Macrophages
Although neutrophils are the primary leukocytes active in acute inflammation, other cell types, particularly macrophages, have important roles.
Macrophages release both pro- and anti-inflammatory cytokines that mediate the inflammatory response; they also release growth factors and enzymes that promote tissue repair. We learn more about the complex actions of macrophages, elsewhere.
