Does the panda blood in "The Storm" indicate that there is a "big human secret" hidden in the play?

In literary and artistic works, panda blood is a standard feature of overbearing CEOs, especially Long Aotian. Although not all holders are cute and have dark circles under their eyes, it is as rare as a giant panda. As a "prop", it is often used to increase the mystery of the characters or the dramatic conflict. But in real life, what kind of blood is panda blood?

01

Why is human blood “not the same”?

For ease of understanding, let's put aside the topic of panda blood and talk about some background knowledge. As we all know, human blood is like human joys and sorrows, and is not universal. In 1900, Austrian scientists discovered that different people carry different antigens on their red blood cells: some carry A antigens, some carry B antigens, some have both antigens, and some have neither. Based on this, human blood can be divided into four types: A, B, AB, and O, which is the ABO blood type system that everyone is familiar with today.

There are many antigens in nature that are similar in structure to A and B antigens. The human immune system will generate corresponding antibodies when it comes into contact with these antigens, so anti-A antibodies and anti-B antibodies often exist naturally in human plasma. However, some antibodies and antigens do not get along very well, just like cats and fish, dogs and meat, Ultraman and little monsters, which are "must be beaten up when they meet". Therefore, the immune system will tolerate the antigens of its own red blood cells and will not produce corresponding antibodies to harm itself. Once a large number of foreign antigens or antibodies invade, the corresponding red blood cells will rupture due to antibody attacks, which is "hemolysis". Therefore, the distribution of ABO blood type antigens and antibodies in human blood is as follows:

Image source: Author

You see, if A enters B, anti-B will target B's red blood cells, and if A enters O, A's red blood cells will be targeted by O's anti-A. With reference to this picture, you can easily understand many blood transfusion rules. For example, when transfusing whole blood, you should try to transfuse blood of the same type, otherwise your own antibodies will hammer out other people's red blood cells, or your own red blood cells will be hammered out by other people's antibodies; for example, when only red blood cells are needed (yes, blood transfusions can only transfuse specific components as needed, not only whole blood), people of all blood types can accept red blood cells from type O blood (that is, type O blood is a universal blood donor), and type AB blood can accept red blood cells from all blood types (that is, type AB blood is a universal blood recipient).

02

Lose... I am numb

The trouble is that there are more than just two antigens on red blood cells, A and B. In 1937, the Austrian scientist who discovered the ABO blood type and another scientist discovered another blood type in the blood of rhesus macaques, so the first two letters of the English name of the rhesus macaque were named the Rh blood type, the most famous blood type other than the ABO blood type.

Later, more red blood cell antigens were discovered. These antigens or antigen groups, like ABO blood type and Rh blood type, all come from a single gene or a closely related homologous gene group, thus giving rise to more blood type systems [1]. As of September 2022, the International Society of Blood Transfusion has identified 43 recognized blood type systems, including 349 red blood cell antigens [2].

Although there are many types of blood type systems, the most important ones are still ABO and Rh blood types, because these two blood type systems are most likely to cause severe hemolytic reactions and endanger life safety. Domestic blood transfusion regulations list these two blood type systems as mandatory items for checking before blood transfusion (Rh blood type does not need to be checked during emergency rescue and emergency blood transfusion) [3]. Other blood type systems can occasionally cause hemolysis, so before transfusing blood and some blood products, even if the ABO and Rh blood types are consistent, cross-matching must be performed to ensure that there will be no immune rejection reaction between the red blood cells and plasma of the donor and recipient.

The distribution of blood types in different systems varies greatly among the population. In China, the distribution of A, B, O, and AB blood types is 28.72%, 28.17%, 34.20%, and 8.91%, respectively[4]. Rh blood type is much more "biased". Compared with the highest negative rate of 35% in other ethnic groups, the Rh negative blood population of the Han Chinese in China only accounts for 0.3% [5]. If ABO blood type is added, the number of people with a specific blood type is even smaller. For example, based on the Han Chinese AB type of 9.08%[6] and Rh negative blood of 0.3%, the Han Chinese AB type Rh negative blood population only accounts for 0.02724%. Perhaps because it is important but rare, the domestic media often refer to Rh negative blood as "panda blood."

So the question is, since panda blood is so rare, what should we do when we need a blood transfusion? In fact, many public welfare organizations for rare blood type mutual donation have been established in China to help each other. But before that, we need to get rid of a misunderstanding: panda blood is not just panda blood.

The Rh blood type system is divided into positive and negative. Positive means carrying Rh antigens, while negative means not carrying them. However, unlike the ABO blood type system, Rh-negative people do not naturally carry antibodies most of the time, so the distribution of antigens and antibodies of Rh blood type is as follows:

Image source: Author

As long as people with Rh-negative blood do not have antibodies, the first transfusion of Rh-positive blood will generally not induce hemolysis[7]. However, considering that antibodies may be produced later due to this contact, transfusion of positive blood is often a "trick" that can only be used once. Therefore, when negative blood is available, negative blood should be given priority . If negative blood is not available, you should not hesitate to use positive blood. After all, only when you save a life can you talk about future risks.

Some people may think that although panda blood is rare, it is hereditary after all. If it is hard to find in the vast sea of ​​people, is it also hard to find among blood relatives? This is not necessarily true. Rh blood type, like ABO blood type, follows Mendel's law of inheritance . If you know how ABO blood type is inherited, you can understand the inheritance pattern of Rh blood type:

Assuming that the gene expressing positive Rh antigen is D and the negative gene is d, then DD and Dd are both Rh positive, and dd is Rh negative panda blood. If the child is dd, the parents may be panda blood dd or carrier Dd. In addition, due to the restrictions of ABO blood type, it may not be able to help during blood transfusion. Some viewers saw that in the drama "Kuangchuan", police officer An Xin took the initiative to donate her "panda blood" to Gao Xiaochen, and began to imagine that there might be some "human secrets" hidden in it. Now you know, although this imagination is very big, it is really unnecessary.

Moreover, even if the blood types of parents and children happen to match perfectly, they cannot donate blood directly. Blood transfusions between close relatives, especially when the recipient is in an immunosuppressed state, can cause a rare but highly lethal complication called transfusion-related graft-versus-host disease. The principle of the disease is that the lymphocytes in the donor cells attack the tissues and organs of the recipient, causing a severe autoimmune reaction and leading to death. However, prevention is also simple. Before transfusion, the risk factors for transfusion-related graft-versus-host disease are routinely assessed. If the recipient is immunosuppressed, the donor is a first- or second-degree relative or a genetically homogeneous group, or there are other risk factors, the blood can be irradiated or frozen and thawed to inactivate the lymphocytes.

Anyway, there are so many rare blood types that it is far from enough to describe them all in one word: panda. I propose that the Yangtze alligator, Chinese sturgeon, and lotus leaf fern be included in the candidate names of rare blood types. Do you have any good suggestions?

References:

[1] Daniels G, Reid ME. Blood groups: the past 50 years. Transfusion. 2010;50(2):281-289. doi:10.1111/j.1537-2995.2009.02456.x

[2] https://www.isbtweb.org/isbt-working-parties/rcibgt.html

[3] Clinical blood transfusion technical specifications[J]. Clinical blood transfusion and laboratory testing, 2000(03):1-11.

[4] Sun Y, Wang L, Niu J, et al. Distribution characteristics of ABO blood groups in China. Heliyon. 2022;8(9):e10568. Published 2022 Sep 8. doi:10.1016/j.heliyon.2022.e10568

[5] Pandya PP Wapner R Oepkes D Sebire NJ. Fetal Medicine : Basic Science and Clinical Practice. Third ed. London?: Elsevier; 2020. https://search.ebscohost.com/login.aspx?direct=true&scope=site&db=nlebk&db=nlabk&AN=2468589. Accessed February 4 2023.

[6] Long Youguo, Huang Wenqiang, Yu Yuesheng, Long Sifang. ABO blood type distribution among 56 ethnic groups in China[J]. Foreign Medicine (Medical Geography), 2010, 31(01): 22-25.

[7] Meyer E, Uhl L. A case for stocking O D+ red blood cells in emergency room trauma bays. Transfusion. 2015;55(4):791-795. doi:10.1111/trf.12925.

Author: Fei Dao Duan Yu

Review | Liang Xiaohong, Professor of Immunology, School of Basic Medical Sciences, Shandong University