Neutrophils are granular white blood cells. It is an active phagocytic cell. Neutrophils arrive at the infected site within 30 minutes of receiving the signal from the infected site. Opsonin substances in neutrophils recognize pathogens. The proteolytic enzymes of neutrophils then rapidly destroy the bacteria. A neutrophil can ingest 3-20 bacteria. After ingestion of microbes, neutrophils die and are excreted as pus.
Neutrophils secrete special chemicals. These chemicals stimulate monocytes and macrophages to eat bacteria. The chemical increases the rate of the phagocytosis process.