Original title: It's up to you, immune system
"Yang" may be the two words you most often see in your circle of friends recently. Three years later, many of us finally began to face off with COVID-19. First, there was a persistent high fever, and then there was a pain like swallowing a blade in the throat. It is no wonder that many friends who had fun in hardship once again offered the omnipotent lines of the Legend of Zhen Huan: "Cutting autumn hurts my head." "Baojuan, my throat..."
On the battlefield of the body, the human immune system is the main force in fighting against viruses. Whether it is high fever, pain, redness, swelling or inflammation, it is proof that immune cells are struggling. Therefore, it is very appropriate to call them "battle cells". Philip Detma systematically explained the disease resistance principle of the human immune system in Fighting Cells, so that we can understand how such an important human system protects us in our daily life.
The book explains a lot of immune mechanisms in detail, and those professional words that you usually do not understand or know only a little, such as inactivated vaccine, nucleic acid, B cell, T cell, white blood cell, antigen, antibody, receptor, complement protein... After reading this book, you will "suddenly understand". Those knowledge misconceptions that have misled us for a long time, such as the statement of "enhancing immunity", are actually not rigorous. After turning over this book, you will find that the "immunity" to rumors is also increasing.
Combat Cell
Written by Philippe Detma and translated by Li Chaoqun
Our bodies are fighting all the time
Source | Pfizer x View the Ideal Life Book List
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Immune system:
A great contributor who has been ignored and misunderstood
Today I would like to introduce a book, Immune, written for the immune system by Philippe Detma, a German science communicator. Its Chinese version is published by the Republic, and its Chinese name is "Battle Cell". For convenience, we will call it "Battle Cell" later, because this name is really appropriate.
The immune system is a relatively unfamiliar field to ordinary people, and there are many professional terms. But the author helped us overcome the conceptual obstacles through vivid metaphors. At the same time, he simulated the operation mode of the immune system through interesting stories. For example, he called immune cells "combat cells", and gave various components or processes of the immune system some pet names, Such as "Killer University", "Cafeteria" and so on.
Therefore, the process of reading a book is like watching a movie or TV play. Even if you have never been exposed to medical knowledge, it will not affect your reading and understanding in any way.
To get to the point, what is the immune system and what does it mean to us?
To answer another question, what is the immune system doing every day?
Everyone has been vaccinated since childhood, especially in childhood. These vaccines have made outstanding contributions to human resistance to pathogen invasion. For example, smallpox, a deadly virus in the past, has been declared eliminated by the World Health Organization; Under the COVID-19 epidemic, many of us have also been vaccinated, which also has a very obvious effect on reducing the risk of severe cases.
So why can a small dose of vaccine provide us with so much protection? This is actually invented by scientists based on the cognition of human immune system. In short, vaccines tell our immune system to prepare for a specific pathogen through mild stimulation, so as to prevent disease before it happens.
Philip summed up the great contribution of the immune system in this way: "The immune system provides us with comprehensive protection, from colds, scratches, cuts and other minor problems to life-threatening cancer, common pneumonia and even 2019 COVID-19 pneumonia （COVID-19） Such fatal infection and so on, it is playing a role... "
Although the immune system is closely related to our health, it always seems that it is not working. This is often a misunderstanding.
For example, when we have fever and inflammation, we usually think that we are sick and the immune system is invalid. But in fact, fever is a process in which the immune system suppresses the growth and reproduction of pathogens, or even kills pathogens by raising the body temperature; Behind the inflammation, redness, swelling and pain of the wound, there are a lot of body fluids with reinforcements to support the immune cells. At the same time, the pain reminds us to pay attention to the injured part.
These are a kind of self-protection of the human body under the regulation of immunity, and are the performance of the immune system in its work, but they are deeply misunderstood.
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Composition of immune system:
A sophisticated and complete "old brand" army
The emergence of the immune system is far more distant than we thought. 3.5 billion years ago, life was just beginning to appear on the earth at that time, and there was only primitive single cell life. They needed to convert the surrounding chemicals into energy necessary for their own survival. But some cells wanted to take a shortcut and steal energy from other cells, so there was mutual absorption of energy, And even devour each other. But other cells are not fools. In order to prevent invasion and maintain their own energy, they formed the initial immune system.
After 3 billion years, to about 500 million years ago, multicellular animals began to grow explosively. In contrast, in the eyes of unicellular organisms, these multicellular animals are naturally behemoths, and they can also provide themselves with endless nutrition.
From the very beginning, multicellular organisms faced the threat of invaders and parasites such as bacteria and viruses. In this severe living environment, the immune system of multicellular organisms naturally gradually improved and matured. It can be said that all existing animals and plants, from single celled organisms, have immune systems. Later, after the emergence of human beings, the immune system became more complex.
It is not easy to answer what the human immune system is, but since it is called "system", it means that it is not a single thing, but a complete system. The author compares the human immune system to "a set of military system", saying that it "is a complex network covering the whole body composed of hundreds of camps and recruitment offices", which means that the immune road network is the "infrastructure" of the immune system.
The so-called "camp" actually refers to the specialized immune organs in the immune system, such as bone marrow, thymus, cecum, tonsil, etc. Some of these immune organs are also the birthplace of immune cells.
In addition, various immune active substances, or "cytokines", are also released from the inside of immune cells, such as antibodies, complements, immunoglobulins, etc. They are also important components of the entire immune system.
According to different immune functions, the immune system consists of two kingdoms, namely, innate immunity (or non-specific immunity) , and acquired adaptive immunity (or specific immunity) 。 From the name, we can see that the difference between the two is that innate immunity is something we have at birth, or it is not specific to a single pathogen.
The author described innate immunity and said, "You can think of it as a novice suit: it contains all the basic tools, but there is no special tools only available in advanced suits." But the author went on to point out: "Without basic tools, special tools are useless." So it still affirmed the great contribution of innate immunity.
In general, physical barriers, such as skin and mucosa, and the innate immune system can prevent pathogens from invading the organism. But when they "break the defense," the acquired immune system is needed to help kill the enemy.
Compared with those stupid soldiers who "don't like thinking" in the innate immune system and only like "hitting the head on", the members of the acquired immune system are more like intellectuals who have superior memory and strategy. They have mastered the basic information of all possible invaders, and then capture and eliminate the invaders by producing special protein weapons and special cells.
However, although the acquired immunity is powerful, its efficacy will change with people's age. For example, when people are born, they do not have such immunity. Although it will be strengthened later, it will be weakened in old age. At this time, they can only rely on innate immunity to play a role.
The author compares innate immunity and acquired immunity to the two kingdoms of the human immune system, saying that "the two kingdoms have very profound and complex interweaving, and part of the magic and beauty of the immune system is also presented in the interweaving of the two systems".
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Operation of the immune system:
The story of being punctured by nails
Since the immune system often works silently, we generally do not know how it cooperates organically. So next, let's imagine a scenario where the immune system works.
Suppose that it's hot in summer, but you want to go out for a walk, so you wear sandals and walk into a small forest. As a result, your big toe is suddenly punctured by a rusty iron nail.
When the nails pierce the toes, a batch of bacteria attached to the nails that accidentally enter the human body are naturally overjoyed, because the temperature of the human body is very suitable for their growth, and the human body can also provide them with sufficient food. This place is much better than that piece of broken forest.
But for the cells living in our bodies, this is a disaster, hundreds of thousands of cells will die, and more cells may be injured. At this time, the immune system began to officially debut.
Source: Battle Cell
The first response is the innate immune system. Macrophages, as "sentries", are the first to arrive at the scene, and they will quickly become violent, spreading their octopus like arms to pull and devour all the enemies around them.
Then, neutrophils, as reinforcements, also rushed to the battlefield and turned into crazy killers, which also opened the rage mode. What is special about neutrophils is that once activated by the distress signal of the invaded cells, their life will become very short.
In order to destroy the enemy as many as possible in a limited time, they will become "crazy" and lose the ability to distinguish between ourselves and the enemy. When killing the enemy, they will often destroy organizations that can protect themselves. Even in the end, they are willing to sacrifice themselves to release lethal chemicals to kill bacteria by breaking themselves.
At this time, platelets also came on the scene quickly. They quickly gathered to the wound and formed a temporary barrier by adhering to the surrounding red blood cells. They stopped bleeding quickly while blocking the enemy's continued invasion, creating conditions for the recovery of the wound.
At the beginning, we mentioned the phenomenon of "inflammation". Generally, the immune system will command the body to make inflammatory reaction at this time, and we will feel slight swelling and pain. This is because after the infection of bacteria, the vascular wall cells are deformed, so a large amount of plasma in the blood seeps out to the damaged infection site. But the immune system makes such a response, in fact, there is a deep meaning behind it.
First, the blood will bring extra body temperature, which will help reduce the activity of bacteria and put pressure on their activities. For normal cells with repair function, proper warming will improve their metabolism and promote rapid wound healing.
Secondly, pain is a powerful stimulus signal that will activate the operation of other parts of the immune system.
Finally, when the injured part is swollen and painful, people will be forced to rest, so that the injured part does not need to continue to bear the burden, and can buy more time to repair it properly.
Therefore, in general, mild inflammation can not be interfered with. If drugs are used immediately in the initial stage of inflammation, it will hinder the work of the immune system. However, it should be noted that when inflammation becomes chronic, it may become the number one enemy of human health.
If all goes well, with the help of macrophages, neutrophils, platelets and inflammatory reaction, all the invading bacteria will be eliminated, and the battle will end. But if the intruder is stubborn, then another great general in the innate immune system will come on the scene, that is, dendritic cells as intelligence agents.
On the one hand, dendritic cells can also help macrophages and neutrophils kill enemies, but they tear up bacteria mainly to collect antigens attached to bacteria, and then transmit information to helper T cells in the acquired immune system.
The helper T cells receiving specific antigens will replicate and grow rapidly, and then the soldiers will come to the battle scene in two ways, some of them will release cytokines to stimulate macrophages to enhance combat effectiveness, and also strengthen inflammatory response. Another group of helper T cells will deactivate another kind of acquired immune cells, namely, B cells, which can quickly subdue bacteria by producing antibodies.
The reason why helper T cells can receive the information transmitted by dendritic cells is that they have specific receptors that can bind to specific antigens of bacteria.
The author said that the process of using gene fragments to produce these protein receptors in the human body is like preparing for the most incredible dinner in the whole universe, because genes as raw materials are limited, but the immune system is like a talented chef. Through mixing, cutting, and adding raw materials, the human body has cooked billions of dishes - namely, receptors on T cells, These receptors can bind to specific antigens on billions of germs, just like making dishes that satisfy the taste of all these guests.
It may be difficult to remember the names of the cells above. It doesn't matter what macrophages, neutrophils, dendritic cells, B cells, and T cells are. You just need to understand that the immune system is an excellent team, and each cell has different functions. Through various arrangements and combinations, they work together to complete complex therapeutic tasks, Just enhance our self-healing ability.
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Use of the immune system:
Vaccine development and new crown therapy
However, after talking about so many weaknesses and precautions of the immune system, we have to admit that it is very powerful and has greatly promoted the development of medicine. The most typical is the development and research of vaccines.
As the author said: "The fight between human beings and diseases begins and ends with the cells in our body."
Now that we talk about vaccines, we will naturally associate with the new crown vaccine. The new crown has troubled us for nearly three years, but why is it still upgraded step by step and difficult to cure? Here is an additional science popularization.
Source: Battle Cell
First, it is related to the structure and replication mechanism of the virus.
As we know, the size of bacteria is very small, which is only 1/10 of human cells on average, but the virus is smaller, which is only 1/500 of human cells. The virus structure is not complex, but it is extremely effective.
Essentially, it is just a piece of genetic information, and the goal is self replication. However, the virus must live in living cells to reproduce, so it must evolve a very solid shell, which can effectively resist the negative impact of the environment when it does not enter the human body. Once it enters the human body, it will proliferate crazily, and it is difficult to eliminate.
In addition, viruses are more diverse than bacteria, and few drugs that are effective for one virus can be used to treat other viruses. For example, remdesivir for hepatitis C (Redsville) It has been used to treat COVID-19 infection, but clinical trials show that its effect is limited.
Moreover, just like people often change clothes, the virus mutates very quickly. It can constantly evolve, and soon makes antiviral drugs lose their pertinence. For example, this new coronavirus has undergone many generations of changes, so we only need two shots of vaccine at the beginning, and then a third booster shot.
Neocoronas is essentially an inflammatory disease The patient usually has a strong inflammatory reaction, with fever, sore throat and other symptoms.
If the immune system cannot eliminate the invaders, for example, because of the invasion of COVID-19, immune cells will produce more and more "cytokines", which in turn will attract other immune cells, while other immune cells will produce more cytokines based on the uncontrolled immune response, which will progress to an inflammatory crisis event of "cytokine storm", It is more dangerous, even fatal. This is the cause of possible lung injury in patients with COVID-19 infection.
In addition, cytokines can also attack the kidney and heart system, leading to serious coagulation problems, requiring more diverse treatment methods.
However, although it is difficult to treat virus infection, the medical community has developed some drugs for the new crown one after another. It is also hoped that in the near future, we can completely put the new crown behind us and return to the normal life before the epidemic.
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