Human blood groups
Human blood groups began to be studied at the end19 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,which 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, human blood is divided into groupsand does not depend on the race to which he belongs, nor on his age, nor on sex. It begins to form at the very beginning of the embryonic period and remains unchanged throughout life. Human blood groups are his individual biological feature.
In the practice of physicians the most important isoantigenserythrocytes 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 iso-antibodies 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 fourdepending on which isoantigens and iso-antibodies 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 isoantibodies a - Ba, - the fourth group contains only isoantigens A and B - AB0.
The compatibility of human blood groups is affected byThe presence or absence in the blood of one isoantibodies, opposing 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 innorm 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 womb ofembryo can already be found in erythrocytes isoantigens. Their number grows and reaches a maximum by three years of life. Then his 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 isdetermination of the presence or absence in the red blood cells 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 Rh-factor, and 85% of it is not available. 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 usingstandard serums. In erythrocytes, therefore, isoantigens are found. For example, to determine the 4 blood group, erythrocytes and standard serum are placed on a white moistened 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.