Everyone may silently hope that their “immunity” is a martial arts master, and may even hope that: my immunity, the higher the better!
Not really.
What is normal immunity?
Immunity is a general term for the functions of our body’s immune system, and it can be called the “protector” of our body!
It contains three functions, which can be summed up in three words: prevention, control, and stability.
What does
mean?
So-called defense–in medicine, it is called “immune defense”. Contains our body’s ability to identify “suspects” and deal with “criminals”.
In medicine, it is the immune system that recognizes and processes foreign objects that invade the human body, such as viruses, bacteria, parasites, etc.[1][2].
Image source: Zhanku Hailuo
The so-called control——that is, “control”, which is called “immune surveillance” in medicine, that is, to find “unfavorable” molecules in the body at any time, such as mutant cells , virus-infected cells, etc. Once found, deal with it immediately [1][2].
The so-called stability——In medicine, it is called “immune homeostasis”. This function is mainly to maintain the stability of the internal environment of the human body. The human body’s environment includes both the external environment and the internal environment.
The external environment refers to the human body, which refers to the external environment where the human body is located; while the internal environment refers to the cells and refers to the internal environment of the human body, which is what we are The environment in which cells directly live in the body [1][2]. What does this stabilization function mean?
The first and very important thing is to keep the human immune system from attacking “our own people”, that is, our normal tissue cells. This ability is medically called “ immune tolerance”.
Second, Coordination. Coordinate the cooperation between immune organs, immune cells, and immune molecules in the human immune system, as well as the cooperation between the immune system and other “brother departments” of the body, so as to maintain the stability of the human body. These “sibling departments” include the nervous system, endocrine system, etc.
With the above three normal functions, people can resist the external aggression in life, remove the “garbage” (such as aging, damaged and mutated cells) in the body, At the same time, healthy cells and organs that are still working normally will not be “injured” by the immune system [1][3].
Is higher immunity better?
Of course not. A normal immune system is best.
We all know that if the immunity is low or defective, the human body is easily invaded by foreign pathogens (such as bacteria, viruses, fungi, etc.), causing infection and even life-threatening. A typical example is AIDS, a secondary immunodeficiency caused by human immunodeficiency virus (HIV) infection [4].
And the immune system is too high, it can also cause a series of problems.
In medicine, it causes a condition called “hypersensitivity,” when the body’s immune response is too high or too much.
It is a condition of high immunity, but it is easy to cause 4 types of diseases
Hypersensitivity reactions caused by excessive immunity must have a precondition: that is, our body and invading foreign bodies (that is, foreign antigens) are not “first sights in life” [1 ], these antigens can be bacteria, viruses, pollen, food proteins, or antigens on red blood cells of a different blood type than one’s own, or chemical dyes (such as certain cosmetics, paints, etc.).
With such a “one-sided bond”, the body’s immune system somehow remembers these antigens.
At this point, the body reacts:
Some people develop antibodies to antigens – immunoglobulin E (IgE), IgG, IgM.
Some people also develop some sensitized or activated mast cells, basophils, or T cells. What does “sensitization” or “activation” mean?
As you can imagine, these cells look like kittens that have been irritated. Once you step on their tails again, they will do something.
When the antigen enters the human body again, the existing antibodies (IgE, IgG, IgM) of the human body will first rush out to react with the antigen, hoping to “kill the enemy at one time”. Under normal circumstances, this antigen-antibody reaction will help the body remove these foreign bodies that invade the body.
Image source: Zhanku Hailuo
However, in hyperimmune, or hypersensitive patients, things are out of control:
In one case, activated mast cells and basophils, two irritated “kittens,” begin to “rage” and release a series of substances such as Histamine, lipid mediators (such as prostaglandins, leukotrienes), etc. These substances, which sound more “troublesome”, can cause some local or systemic reactions in the human body, such as telangiectasia, smooth muscle contraction in the human body, and increased secretion of fluid from glands.
At this time, people will have various symptoms, such as redness of the skin, sneezing, runny nose, watery eyes, difficulty breathing (caused by the narrowing of the airways), etc., which can cause bronchial asthma , drug eruption, anaphylactic shock, allergic gastroenteritis and other diseases [5].
This condition is medically known as Itype hypersensitivity, also known as “allergy”.
In some cases, in addition to the antigen-antibody reaction, some immune molecules (such as complement) and immune cells (such as phagocytes, NK cells) also participate in the struggle, causing red blood cell destruction, such as transfusion Different blood types lead to hemolysis[6] or this is the case in patients with neonatal hemolysis, which is called Ⅱtype hypersensitivity.
Others are antigens, such as Streptococcus and antibodies that form immune complexes, but are not quickly cleared by the body, but instead stay in places where they shouldn’t be. such as the capillary basement membrane of the kidney.
At this time, post-streptococcal glomerulonephritis will occur [7], which is called Ⅲtype hypersensitivity.
Finally, there is also a situation in which foreign antigens (such as certain cosmetics, plasters, paints, and other chemical dyes) change the composition of some tissue cells in the human body, causing the human body to form a “” Neoantigen”, angered the “kitten” of T cells; when the body was exposed to this dye again, the activated T cells either directly killed the antigen or produced lymphokines to kill.
At this time, the body’s tissues are also damaged at the same time, showing diseases such as contact dermatitis [8].
And this is called IVtype hypersensitivity. Compared with the previous three types, this kind of hypersensitivity reaction occurs slowly, and it takes 2~3 days for inflammatory reaction to appear, so it is also called delayed type hypersensitivity reaction.
Image source: Zhanku Hailuo
Finally, it should be pointed out that due to the complexity of the actual situation of the human body, patients with “high immunity” sometimes have two or three kinds of hypersensitivity reactions at the same time.
What causes high immunity? Why do some people experience hypersensitivity reactions?
Unfortunately, the cause of hypersensitivity reactions is not well understood by the medical community at this time.
At present it can only be speculated that it may be related to genetic and environmental factors[1][5][6][7][8][9].
Under the action of certain incentives, the function of the immune system, especially the excessive immune defense function, leads to the occurrence of hypersensitivity reactions.
To summarize:
Normal immunity can be understood as: the three functions of the immune system are normal and not excessive, namely defense function, surveillance function and stable function.
The higher the immunity, the better.
High immunity has a medical name called hypersensitivity reaction. Although both are hypersensitivity reactions, the diseases they cause are completely different.
References:
[1] Cao Xuetao. Medical Immunology. 6th Edition. Beijing: People’s Health Publishing House. 2013.
[2] Cohen IR, Efroni S. The Immune System Computes the State of the Body: Crowd Wisdom, Machine Learning, and Immune Cell Reference Repertoires Help Manage Inflammation. Front Immunol. 2019, 10 :10.
[3] Stephensen CB. Examining the effect of a nutrition intervention on immune function in healthy humans: what do we mean by immune function and who is really healthy anyway?. Am J Clin Nutr. 2001,74(5):565C566.
[4] Jiao Yanmei, Shi Ming, Xu Ruonan, et al. Research on the basic and translational application of AIDS clinical immunity. China AIDS and STD, 2019, 25(09): 877-881.
[5] Xu Wengang, Li Minghua. The relationship between allergic rhinitis and asthma. Chinese Journal of Clinicians, 2014, 42(12):5-6+2.
[6] Liu Likun. Adverse blood transfusion reactions caused by ABO incompatibilityand Treatment. Hebei Medicine, 2009, 31(24): 3437-3438.
[7] Sinus health. Research progress on glomerulonephritis after acute streptococcal infection. Chinese and Foreign Medical Research, 2020, 18(01): 186-188.
[8] Zeng Qiang, Wang Zaixing. Research progress on the etiology of drug hypersensitivity syndrome. Chinese Journal of Dermatology and Venereology, 2017, 31(12): 1374-1376.
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