Healthy adults with rare blood types should donate blood, but autologous storage can only be regarded as a precautionary measure. The establishment of a rare blood type bank is the main way for people with rare blood types to solve the "difficulty in using blood".
◎Our reporter Chen Xi
Speaking of rare blood types, everyone will think of Rh-negative "panda blood".
In the hit drama "Hurricane", police officer An Xin donated "panda blood" to Gao Xiaochen.
In real life, there are many rare blood types, even rarer than "panda blood".
Recently, the official website of the Baoji Central Blood Station in Shaanxi Province announced that during a routine screening of the blood of an 18-year-old female blood donor, the inspectors at the Baoji Central Blood Station discovered a case of a rare ABO subtype - cisAB blood type.
Rare blood types mainly come from genetics
"Panda blood", "Dinosaur blood", "Golden blood"... Judging from the names, we know that these blood types are precious and rare.
"A rare blood type is a rare or rare blood type. Different countries have different standards for the definition of a rare blood type." Xie Jinhui, director of the Immunohematology Research Office of Tianjin Blood Center, gave an example. In my country, when a certain blood type phenotype If only less than one in a thousand people in the population has it, it can be listed as a rare blood type.
Finland defines a rare blood type as less than 2 per thousand of the population, and France as less than 4 per thousand.
Before understanding rare blood types, we must first understand why humans have so many blood types.
Xie Jinhui introduced: "Human red blood cells carry different antigens. Some human red blood cells carry antigen A, some carry antigen B, some have both antigens, and some have neither. Based on this, the Human blood is divided into four types: A, B, AB, and O, which is the most common ABO blood group system."
At the same time, there are many antigens similar in structure to A and B antigens in nature, and the human immune system will generate corresponding antibodies after contacting these antigens, so anti-A antibodies and anti-B antibodies often exist naturally in human plasma.
During blood transfusion, if blood of different blood types is transfused, a large number of foreign antigens or antibodies invade, red blood cells will rupture due to the attack of antibodies, and "hemolysis" will occur, which may lead to shock, kidney failure or even death in severe cases.
However, with the progress of scientific research, scientists have discovered that there are not only two antigens, A and B, on red blood cells. The most famous blood type besides the ABO blood type is the Rh blood type.
As of December 2022, the International Society of Blood Transfusion has identified 44 recognized blood group systems, such as P, Kell, Kidd, MNS, Diego, Lewis, Lutheran, Duffy and other blood group systems, which contain 354 red blood cell antigens.
"The generation of blood type is determined by genes, and the formation of rare blood types is mainly from genetics." Xie Jinhui explained that, similar to genetic diseases, assuming that the Rh antigen-positive gene is D and the non-positive gene is d, then DD and Dd are both It is Rh positive, and dd is Rh negative panda blood.
If both parents are Dd, then the offspring is likely to be "panda blood" dd, and may also be a carrier Dd.
Coordinating the construction of rare blood type bank
Usually, many tests are carried out before blood transfusion. The four tests that must be carried out are ABO blood type test, Rh blood type test, antibody screening, and cross-matching to ensure the safety of blood transfusion.
Among them, the main purpose of cross-matching blood is to perform compatibility testing and simulate the environment in the human body to ensure that the red blood cells and plasma of the donor and recipient will not have immune rejection reactions between each other.
Xie Jinhui pointed out that the reason why rare blood types are very troublesome is that after transfusion of blood with different antigens, once antibodies are produced, it is very difficult to find suitable blood.
For example, the Rhnull blood type, which is rarer than "panda blood", lacks the antigens of the entire Rh system, which leads to people with Rhnull blood type having only one chance of blood transfusion in their lifetime.
Because after the first blood transfusion, an antibody called "anti-Rh29" may be produced in their blood.
And this antibody will attack red blood cells with Rh antigen, which means that it will be difficult to find a suitable blood type for them afterwards.
"Knowing your blood type is very important for everyone." Xie Jinhui reminded that if you find that your blood type is relatively rare, you may face a very difficult situation in finding blood sources.
For such people, it is recommended that as long as they are healthy adults, they should donate blood in case of emergency.
However, autologous storage can only be regarded as a precautionary measure, and the establishment of a rare blood type bank is the main way for people with rare blood types to solve the "difficulty in using blood".
Blood centers in many provinces and cities carry out rare blood type screening projects among blood donors, and at the same time keep all types of rare blood type blood and the information materials of rare blood type blood donors.
"But now the information and data of rare blood types are managed by each provincial and municipal blood center themselves, and there is no network sharing between the data." Xie Jinhui said that a rare blood type network deployment mechanism should be established so that in emergency situations, Realize Regional blood transfers.