Immunocytes kill pathogens with the help of "bleach"
Last reviewed: 16.10.2021
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Attacking the bacterium, the cells of the immune system - neutrophils - are immediately treated with an oxidizing agent, namely hypochlorous acid.
Human immunity "knows" many methods of combating pathogens. One of these methods is the simplest - it is the devouring of the enemy.
Such devouring is most active in neutrophils, which attack the infectious agent first. But just eating a microbe is not enough - it must be safely destroyed, so neutrophils treat a "swallowed" bacterium with a combination of substances based on a powerful oxidizer. Such an oxidizer plays the role of a kind of weapon, which includes hypochlorite, or hypochlorous acid. This substance is known for the fact that it produces chlorine, it is also chlorine lime, a strong disinfectant and bleach.
Such information became known to specialists relatively long ago. Scientists also knew what enzymatic substances are needed in order to accumulate a "murderous mixture". But until now, it remained a mystery which processes occur in immune cells after the absorption of the microorganism: when the "treatment" of the microbe begins, how quickly the bacterium dies, and so forth. And another question that worried scientists: the neutrophil after eating and processing microorganisms dies after all processes, or even before they are completed?
In order to get answers to all the questions posed, specialists representing the Ruhr and Bonn universities conducted an interesting experiment. They launched into the experimental microorganisms a special fluorescent protein, which is sensitive to oxidation processes. Being in an adequate state, the protein had a green color (after illumination with blue illumination). After the oxidizing action to acquire a green color, the protein should be illuminated not with a blue, but with a purple backlight.
Germs were fed to neutrophils and observed what was happening. It was noticed that already a couple of seconds after the microbes got inside to the immunocytes the luminous protein changed. Speaking more readily, neutrophils treated microbes with a damaging substance almost immediately after ingestion. In their work, scientists noted: judging by the speed of the process and the degree of oxidation of the fluorescent protein, the main oxidant was hypochlorite - the so-called precursor of the famous "bleach".
Another essential component for the destruction of microbes, except hypochlorite, was hydrogen peroxide. But for total damaging action, only a combination of components was needed, since each substance alone did not cause the death of the bacterium.
The information published by scientists makes it possible to understand how immunity fights against microbial invasion, and for what reasons some microbes remain alive even after the attack of neutrophils.
Details of the study are described in the article https://elifesciences.org/articles/32288