A good explanation of how neutrophils, a key element in our immune system, work. As those of us who have experienced low immunity know, our medical team watches our neutrophil levels closely to know when we start to bounce back, as well as our overall immunity. Quote:
Activated neutrophils employ three key killing strategies. First, they can engulf and devour microbes. This process, called phagocytosis, was first described over one hundred years ago by Mechnikov who won the Nobel Prize for Medicine in 1908. In his Nobel lecture he described “white corpuscles of the blood…which absorb the microbes and destroy them” . The process of cell devouring is directed by molecular tags called opsonins which are produced by the body and stick to microbes. Imagine the microbe is a cookie: opsonins are like chocolate chips which make the cookie that much more appealing to the hungry neutrophil. Once consumed, the microbe is exposed to enzymes which kill and digest it.
The neutrophil’s second strategy, called degranulation, kills microbes occupying the local area. The neutrophil releases packets of enzymes which attack the outside of the microbe. This is like pouring boiling oil on invaders; crude but effective. Unfortunately this can cause collateral damage to the very tissue the neutrophils are meant to protect. The damage is limited because the neutrophils are designed to die 24-48 hours after moving into the tissue. As the dead neutrophils accumulate we can see evidence of them in the form of pus.
Even in death the neutrophil works to bring down enemy forces through its third killer creation: Neutrophil Extracellular Traps (NETs). NETs are a relatively recent discovery, outlined in 2004 by Brinkmann and colleagues. NETs are created once the neutrophil’s self-destruct programme has been engaged. DNA, proteins and hostile enzymes mingle within the cell which bursts open in a final kamikaze act that unleashes a web which can trap and kill bacteria. This works against an array of different bacteria, from Shigella, which causes dysentery, to Salmonella, which is responsible for typhoid fever.