Human blood groups

Human blood groups began to be studied at the end of the 19th century in the section of immunology. Without this knowledge, it would be impossible to perform a blood transfusion that saved many lives. Also, the doctrine of blood groups is widely used in surgery, in obstetrics and gynecology, in forensic medicine and in genetics. Knowledge of the differentiation of isoantigens is taken into account when transplanting tissues and organs.

Human blood groups are signs of blood that are transmitted from parents to children. Each has an individual set of group antigens, which these attributes determine. This set of characteristic substances is also called isoantigens.

On their basis, the human blood is divided into groups and does not depend on the race to which it belongs, nor on its age or sex. It begins to form at the very beginning of the embryonic period and remains unchanged throughout life. The human blood group is its individual biological feature.

In the practice of physicians the most important isoantigens of erythrocytes A and B. It also takes into account the isoantibodies a and ß, sometimes contained in the serum of human blood. The simultaneous presence in the blood of isoantigens and isoantibodies belonging to the same type (for example, ß and B) leads to the gluing of erythrocytes and is incompatible with life. Therefore, only heterogeneous substances (for example, A + ß) should be together.

Human blood groups are divided into four depending on what isoantigens and isoantibodies are present in it. They are denoted by symbols in the form of letters and numbers: - in the first group there are only isoantibles a and ß = 0aß - the second group includes isoantigen A and isoantibol ß - Aß, - the third group contains isoantigen B and isoantibody a-Ba, - the fourth group Contains only isoantigens A and B - AB0.

The compatibility of human blood groups is influenced by the presence or absence in the blood of one isoantibodies that oppose isoantigens in the blood of another. This is taken into account in blood transfusion. The use of blood belonging to the same group is considered ideal.

It happens that in addition to the isoantibodies present in the norm in human blood, it receives isoantibles from the outside, resulting in the incompatibility of blood groups. This can occur with the transfusion of blood ingredients (plasma, white blood cells, erythrocytes), all blood; During pregnancy, when the embryo blood group is incompatible with the mother's blood group; After using some vaccines and serums for treatment.

After the first month of life in the uterus of the embryo, it is already possible to detect isoantigens in erythrocytes. Their number grows and reaches a maximum by three years of life. Then its level does not change and only begins to decline in old age. It does not change during a person's life and the whole set of isoantigens in the blood. Its composition is not affected either by the transferred diseases, or the influence of chemical, biological factors.

No less important in medical practice is the determination of the presence or absence in the erythrocytes of antigens of the Rh-Rh-factor system. On this basis, people are divided conditionally on Rh-negative and Rh-positive. It is known that 15% of the population does not contain the Rh factor, and 85% do not. If the future mother does not contain Rh-factor, and the fetus inherited the antigen from the father of the Rh-positive, then antibodies are formed to it. They affect the erythrocytes of the unborn child, causing their destruction (hemolysis).

Determine the blood group of a person using standard serums. In erythrocytes, therefore, isoantigens are found. For example, to determine the 4 blood group, red erythrocytes and standard serum are placed on a white wet plate, left at room temperature, and then the agglutination reaction is observed. With a positive reaction of isoanthil, sera should glue the erythrocytes and turn them into tiny red granules. With a negative reaction, there are no changes at all. In order to avoid an error, a reaction with two samples is put on each group.