Blood groups in the classification used by modern medicine were discovered relatively recently. They were first described at the beginning of the twentieth century, and science has managed to find out a lot about blood groups, but not everything. In particular, there is still no consensus on the origin of different bloods and which group appeared first. Together with experts, we figure out what a blood type is, how to recognize it, and the importance of the Rh factor.
- What is this
- Kinds
- How to find out
- Compatibility
Daryankhum Miftakhova, general practitioner, BestDoctor group of companies;
Ekaterina Kovalenkova, leading specialist of the donation development group of the European Red Cross.
What is blood type
Blood consists of red blood cells, white blood cells and platelets contained in plasma
Blood type is a key feature of a person’s blood, which is inherited and includes various combinations of special antigens (1). The determining factor for dividing blood into groups is the presence or absence of these antigens – protein molecules on the surface of red blood cells (2), (3). Hundreds of such antigens are known to medicine, but the ABO systems and the Rh factor are important to determine the group.
AB0 reflects the presence or absence of agglutinogens on the membranes of erythrocytes and agglutinins in the blood plasma (4). The gene that determines the blood group is located on the 9th chromosome, and its locus (section) has three allelic forms (states): A, B and 0. Each of them is responsible for the production of its own glycoprotein (special protein). The combination of alleles inherited from parents determines which glycoproteins (antigens) are found in blood cells and their blood type (5).
What is Rh blood factor
Rh factor is a special hereditary antigen – a protein that can be present on the surface of red blood cells (6). In the first case, when a person has it, they talk about Rh-positive (+) blood status, in the second, when it doesn’t exist, they talk about negative (-).
A person may belong to one of the groups (7):
- A+
- A-
- B+
- B-
- 0+
- 0-
- AB+
- AB-
The Rh factor itself does not affect health or heredity. But this is an important indicator of blood compatibility, for example, during transfusion and pregnancy. If the expectant mother and child have the same Rhesus, then, as a rule, there are no concerns (6). But if a woman is a carrier of negative Rh and the child is positive, a Rh conflict, or immune blood incompatibility, may occur, in which the mother’s body is able to reject the fetus. Prenatal diagnosis of the Rh factor is carried out from the 10th week of pregnancy. When there is a threat of conflict, special immunotherapy is used (8).
Types of blood groups
The blood type is formed at an early stage of embryonic development, and after birth and throughout life does not change
Blood groups were discovered by the Austrian biochemist Karl Landsteiner. A series of experiments with blood transfusions showed that such manipulations help some people, but are fatal for others. In 1900, Landsteiner identified three blood groups (5). The fourth was discovered a little later by the Czech doctor Jan Jansky. By the 1930s, a generally accepted division of blood groups with letters and numbers took shape: 0 (I), A (II), B (III) and AB (IV). The prevalence of blood types varies, which is why you may hear that some blood is rare and others are not.
Blood type 0 (I)
0 (I) – first group. There are no agglutinogens A and B on red blood cells, but agglutinins a and b are present in plasma. One of the most common is the first Rh-positive blood group. According to various estimates, at least a third of all people living on the planet have such a group. (9). People with first negative blood 0 (-) are considered universal donors, since their blood suits all groups and Rh factors, explains Ekaterina Kovalenkova, leading specialist of the donation development group of the European Red Cross.
Blood type A (II)
A (II) – second group. It is characterized by the presence of agglutinogen A on erythrocytes in the absence of agglutinogen B. The plasma contains agglutinin b, but no agglutinin a. Such blood is also considered one of the most common (9). The prevalence of a second positive blood group is significantly higher than with a negative Rh factor.
Blood type B (III)
B (III) is the third group. Red blood cells have agglutinogen B, but no agglutinogen A; plasma has agglutinin a, but no agglutinin b. The third group, both positive and negative, is much less common (9), positive – in 8%, negative – in 2%.
Blood type AB (IV)
AB (IV) – fourth group. It is distinguished by the presence of agglutinogens A and B on erythrocytes and the absence of agglutinins a and b in the plasma. This blood group is considered one of the rarest. According to various estimates, the prevalence of the fourth group (positive and negative) is about 2% and 1%, respectively. (9). Carriers of the fourth blood group are considered universal plasma donors (6). In addition, people with IV positive AB (+) blood are suitable for blood of any group and Rh factor, notes Ekaterina Kovalenkova.
AB0 blood system (4)
How to find out your blood type
Blood groups are determined by the method of erythrocyte agglutination or red blood cell adhesion using special sera, says Daryankhum Miftakhova, a general practitioner at the BestDoctor group of companies. To determine your blood type, red blood cells are mixed with various antibody solutions. If, for example, a solution contains anti-B antibodies and the cells being tested have B antigens, it will clump together (7).
The most reliable result comes from laboratory testing.
There are three methods: direct, cross and zoliclon. The difference between them is serums and solutions. The method of determining the blood group is not particularly important; it is much more important to properly prepare for the test.
General rules for preparing for blood donation:
- before conducting any blood test, exclude fatty foods from the diet for a day;
- When donating blood you need to be healthy. You should not have fever or other acute manifestations of illness.
Most laboratories usually collect blood in the morning, but the time of day is not important for determining blood type. You can find out your blood type and Rh factor in a city clinic under the compulsory medical insurance policy and in any medical center. The analysis takes up to two days. The results are allowed to be entered into a civil passport (10).
Accounting for the results of determining the AB0 blood group (11)
Blood group compatibility
Transfusion of the wrong type of blood is dangerous for the patient's life. According to current standards, transfusion is carried out strictly within the same blood group and if the Rh factor matches, says Daryankhum Miftakhova.
In emergency cases, patients with blood group A (II) or B (III) can be transfused with negative blood components of group O (I), and carriers of AB (IV) – group B (III) with negative Rhesus. Also, for health reasons, a person can be transfused with no more than 500 ml of components of negative group 0 (I), regardless of the group and Rh factor of the recipient (11).
Knowing your blood type and Rh factor is important for several reasons.
Is it possible to find out your blood type at home?
It is impossible to find out your blood type at home. This requires special equipment and reagents. Plus, skills in drawing blood and conducting research are required. They are performed only by specially trained medical personnel in laboratory conditions.
