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How does immunity work - and why it cannot be strengthened

Wherever we are, these creatures haunt us on the heels. They sit on doorknobs, on computer keyboards, on staircases and, not least, on our skin. This refers to pathogens of diseases - bacteria, viruses and fungi, most of which are not dangerous for us due to immunity - congenital and acquired. How does it work and is there a need to "improve immunity"?

It is necessary to thank the immune system for the fact that microbes do not conquer our entire body, and some of them even coexist with us in a kind of symbiosis. It is immunity that provides peaceful parity between our needs and those of these tiny fellow travelers.

If the army of our body - so to say without exaggeration, we could call the immune system - did not offer constant resistance to all pathogens with which we come in contact, we would rather quickly earn an inflammation of the heart muscle or a bunch of other diseases.

However, the immune system works not only against disturbers of the body that are alien to the body, but also against our own cells, if they degenerate or become cancerous. Of course, this is greatly appreciated: there must be someone in the household taking care of the order. But sometimes our army goes too far and attacks healthy structures - then they talk about autoimmune diseases.

There are two types of immunity - congenital and acquired. They have one task - to protect the body from the spread of pathogens in it, attacking tissues and organs. But there are significant differences in how they do it.

How does innate immunity work

Inborn immunity is transmitted to us from the mother at birth, as is clear from the very name. An example of innate immunity is the acid mantle of the skin, because on the acidic surface pathogens are unlikely to survive. Or lysozyme in saliva is an antibacterial enzyme that meets unwelcome guests already in the mouth.

Slippery mucous integument containing antibacterial substances is also an effective defense tool of the body, related to innate immunity. Who without special equipment will climb on the wall covered with slime?

An army of immune cells protects us day after day. As in this army, it has special units and warriors specializing in certain tasks.

On the front line of the front, granulocytes are fighting. Like other immune cells, they are among the white blood cells, or leukocytes. The latter differ from their red counterparts in that they have a cell nucleus, but there is no hemoglobin that retains oxygen.

If during the "control walk" granulocytes find out that the pathogens of the disease have started in the body, they immediately notify their relatives, who are lined up with a chain and ruthlessly destroy every invader in their way with the help of poisonous substances.

With the surviving pathogens, huge devouring cells - macrophages - instantly punish the place. In the event of an infection — that is, invasion of pathogenic microbes into the body — regulatory proteins direct them to the scene of the events, and macrophages, without delay, eat up all the excess that they find. If they need reinforcements, they call him in the blink of an eye using an ingenious communication system.

These mechanisms were developed over millions of years of evolution, but even now they do not cease to adapt to the spirit of the times and to current requirements. Innate immunity has its own "internal investigators" - they are called natural killer cells. Good title, right? In contrast to the police officers, they act very harshly, such as Rambo.

The task of killer cells is to detect and neutralize diseased cells, thereby preventing them from growing into a malignant tumor even at the initial stage. To do this, they ruthlessly force the cells that have degenerated or affected by pathogens to suicide, which is called apoptosis.

A certain part of the cells of our body is constantly ready to mutate, that is, to change the hereditary information. Then, with the next division, a generation of diseased cells arises. If the killer cells did not recognize and neutralize them in the shortest possible time, it could end very badly for us.

The army of immune cells is continuously replenished by recruits. She finds them with the help of special neurotransmitters - interleukins, which, among other things, contribute to the fact that white blood cells grow, mature, share and eventually become more active.

It seems that our army is invincible, but it is deceptive. Yes, the innate immunity very quickly reacts to uninvited guests, but as far as methods of dealing with them are concerned, it is rather a conservative. When the same pathogen causes the infection, whether for the first or the hundredth time, the innate immunity invariably responds in the same way. If the measures taken by him help, there are no problems, but if this is not enough, support is urgently needed.

Acquired immunity: what is it?

Here we come to the acquired immunity. It is much more inventive than the innate, because it has the ability to learn. Each conqueror bears the distinctive insignia, and the cells of acquired immunity can recognize them.

Destroying dangerous microbes is not all: here the cells behave like Indians in westerns - they are not just ruthlessly cracking down on the enemy, but they scalp it and expose the scalp for public viewing as a trophy. So characteristic features of the enemy are imprinted in the memory of other immune cells for at least a couple of years.

If the cells of acquired immunity at least once faced with a specific causative agent of the disease, then they will definitely remember this. Immunity produces so-called memory cells, which react immediately at the next meeting with the same pathogen. To do this, they use the services of B-lymphocytes and T-lymphocytes.

The task of B-lymphocytes is to purposefully protect the body from pathogens and other foreign substances. To this end, they produce antibodies that immediately respond to the typical signs of a known microbe (think of the scalp), bind to it and thereby neutralize. Like a kind of handcuffs.

Want a little more detail? Good. When inactive B-lymphocytes, rushing through the blood, encounter an alien substance - the so-called antigen, they seize it without delay, cut it up and put fragments on their surface. This is a signal for another form of lymphocytes, helper T-cells, to immediately release regulatory proteins.

“T” here, by the way, means the organ in which these cells mature, the thymus, or the thymus gland, located behind the sternum. It is important for us primarily in childhood and adolescence. Later, it is less used for the maturation of T-cells and gradually atrophies until there is only a tiny and almost inactive wen.

Now T-cell proteins activate B-lymphocytes, they immediately go to the lymph nodes and spleen, where they rapidly divide. In the process, they are guided by the motto “more is better,” producing various antibodies until an antibody is obtained that is ideal for combating the agent that has entered the disease. A small part of these B-lymphocytes develops further, turning into the memory cells mentioned above, which the invader will remember for a long time.

At the last stage of maturation, B-lymphocytes finally become plasma cells. They no longer have the desire to multiply, and from now on they produce only the very antibodies that are suitable for controlling a particular pathogen. Almost like an elderly person who continues to work with pleasure at a good age, but he does not want to have children.

As you can see, the immune system is quite complex. Immunity should be able to accurately distinguish its own cells from alien ones and instantly recognize pathogens. If the defensive army so skillfully did not restrain the onslaught of enemies who constantly threaten our blood vessels, heart, other organs and tissues, and did not neutralize them, we would not have lived for a long time.

Watch the video: The Immune System Explained I Bacteria Infection (October 2019).