World Blood Donation Day | Why can't type A blood be lost to patients with type B blood?Can you

Produced: Popular Science China

Author: life pulse team

Produced: Computer Network Information Center of the Chinese Academy of Sciences

Every year, June 14th is the World Blood Donation Day. For blood donation, everyone may be most impressed by the blood donation vehicle on the street, and many people may not understand: Why should we actively donate blood?

This is mainly because blood is very important in clinical treatment, and demand is large, but there are no artificial alternatives at present. Therefore, it is important to ensure sufficient blood library resources.

So why are there different blood types, why can't we use blood between different blood types, and can we create "artificial blood" to relieve blood pressure?

What is determining our blood type?

When clinical treatment requires blood, the first thing to consider is blood type, and the essence of blood type is actually the antigen type carried on the surface of red blood cells in human blood.

The antigen in the ABO blood type system is A, B, and H, which is the sugar chain connected to the lipid and protein.

The red blood cells of type O (referred to as expression) H antigen on the red blood cells. Although people with type A blood also carry the H antigen, the gene they carry can transform the H antigen (referred to as modification) into A antigen. The B gene carried by the type of blood can modify the H antigen into the B antigen. AB -type people carry the A and B genes at the same time, which can modify the red blood cell surface to modify the surface of the red blood cells into A antigen or B antigen.

ABO blood type system and its corresponding A, B, H antigen schematic diagram (Source: freepik.com)

The RH blood type system is a system that is independent of ABO blood type. Its antigen is protein on the surface of red blood cells, including C, C, D, E, E, etc. Among them, the D antigen is the most important type. People with the D antigen are called RH (D) positive, and those without the D antigen are RH (D) negative.

In China, more than 99%of people have the D antigen. When the blood transfusion is distributed, it does not need to consider the consistency of the RH blood type system.

However, 1%of people are RH (D) negative blood types. Because of rare, they are often much more dangerous than ordinary people when they need blood transfusion, because the blood storage is difficult to have sufficient reserves for their blood. ) The negative blood type is also called "panda blood".

Therefore, the blood type pairing must be performed in advance when transfusion, otherwise a major problem can be obtained.

Why pairing blood type?

The reason why the blood type antigen is called "antigen" is because they can cause the human body's immune response. If a human body enters the original antigen, the immune system will attack these heresy to ensure the purity of the body's environment.

In the process of blood transfusion, if a person with type O blood is input to type A or B blood, his/her immune system will attack the A or B antigen that has never been seen before. This immune attack can cause adverse blood transfusion reactions such as red blood cells (hemolysis), and in severe cases, there will be danger of life.

Conversely, if people with type A or B blood are input to type O red blood cells, their immune system will not attack the new O -type red blood cells because they have seen the H antigen.

Red blood cell hemolytic reaction imagination (Source: freepik.com)

The same is true for a person with RH (d) in RH (d). Event.

Foreign blood donation public welfare advertisements, ABO blood type and RH blood type are distinguished very clearly (Source: freepik.com)

In addition to calling for blood donation, scientists are also actively solving the problem of blood use difficulties.

In order to solve the problem of blood use, scientists have been trying various methods, such as finding enzymes that can restore A and B antigen into H antigen in vitro to create universal O -type red blood cells; or try to use artificial manufacturing simulation blood to develop and develop Great, easy to save and use red blood cell substitutes, realize blood transfusion, and so on.

Especially for rare "panda blood", it is easier to encounter problems with insufficient blood sources. To this end, the joint research team of Professor Tang Ruikang of Zhejiang University and the Second Affiliated Hospital of Zhejiang University School of Medicine and Associate Professor Wang Ben of the Transformation Medical Research Institute proposed a solution through many years of research. They successfully put on a special "jacket" to red blood cells, so that the blood supply and the blood can also be transfushed with blood types, realizing the artificial construction and safe blood transfusion of "general panda blood".

Source: freepik.com

Specifically, the research team uses a three -dimensional gel network similar to the outer layer of the cell membrane to wrap RH (D) positive red blood cells, which is equivalent to putting a "jacket" for red blood cells to let the red blood cells carry D itself D. The antigen is hidden in the three -dimensional gel network, so that it will not be identified by the immune system, and naturally does not cause an immune response.

The preparation process of "GM Panda Blood" (Source: "Scientific Progress")

Speaking of which, some people may have questions: Can red blood cells wearing "jackets" still play its function?

The answer is yes, because the "jacket" is soft and transparent, so it will not affect the flexibility of red blood cells, and it can ensure that the oxygen and carbon dioxide passes normally.

In addition, researchers also predict that this layer of "jacket" can also cover the A and B antigen in the ABO blood type system, making the transformed red blood cells a general O -type.However, there is still a distance from the clinical application of the study, and some problems need to be solved.

The theme of this year's World Blood Donation Day is "Blood donation is a unity. Join us and save lives", which actually tells us that protecting us with blood safety can not rely on the strength of one aspect or someone. Scientists are actively at the scientific research level.Efforts, we can also ensure sufficient blood for blood decks by donating blood. Maybe a patient with a dying life will be healthy because of your efforts!

Reference materials:

1. https://advancess.sciencemag.org/content/6/12/eaaw9679

2. http://www.news.zju.edu.cn/2020/0323/c775a1987713/pagem.htm

3. https://www.jbc.org/content/295/2/325.long

4. https://en.wikipedia.org/wiki/blood_substitute

5. https://zhuanlan.zhihu.com/p/27318087

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