Blood groups: blood transfusion scheme, Rh factor

Different blood groups have a number of distinctive components, which can be negatively reflected when two different groups are combined. внутри организма. This phenomenon is explained by the presence on the surface and in the plasma of each individual group of an individual combination of agglutinins and agglutinogens that are able to distinguish the foreign erythrocyte from its own, to prevent its functioning inside the body. The immune system of a person with cells with an external agglutinogen is perceived as a threat. And for protective purposes, the body seeks to damage and remove them with the help of agglutinins contained in the plasma of their erythrocytes.

Even before the beginning of the XX century it was believed that you can combine any blood, which was fundamentally wrong. And sometimes it all ended even with lethal outcomes, because the transfused blood was not perceived by the body. The adhesion and destruction of erythrocytes was developing. But thanks to K. Landsteiner, who was able to detect and prove the presence of agglutinogens and agglutinins in erythrocytes, blood groups are now distinguished, and the blood transfusion scheme has become safe.

Blood types

The system developed by Landsteiner has the name ABO. It classifies four blood groups depending on agglutinogens, designated A and B and agglutinins a, b in the composition.

Agglutinogens (antigen) - complex substances located on the erythrocyte membrane, are unchanged and hereditary from parents.

Agglutinin (antibodies) - immunoglobulins, produced in the plasma of erythrocytes naturally to protect the body from genes that are absent on the surface of the erythrocyte. They are developed during the first year of life, as a protective function of the immune system to get proteins with foreign antigens.

As can be seen from the table, each blood group difference is a set of antigens and agglutinins that have developed to the missing antigens for protection. In the plasma of erythrocytes, agglutinins of the opposite species are produced from antigens on the membrane. This opposite exists so that when the foreign blood group gets into the body of the red blood cells, they are quickly destroyed by antigens, without damaging their cells.

Rhesus factor of blood

In the scheme of blood transfusion of groups of permissible overlapping, it is also necessary to take into account the Rh factor of blood. Rhesus factor - a constant characteristic that does not change with the course of life and is a classification of blood in the Rh system. The Rh system is based on the detection of six antigens C, D, E, c, d, e on the surface of erythrocytes, was discovered in 1940 by K. Landsteiner and A. Weiner.

If an antigen D is found on the surface of red blood cells (occurs in 80% of people) or simultaneous presence of C and E antigens, the blood belongs to a positive Rh factor, designated Rh +. In the event that no antigens of this group are detected, then the Rh factor will be negative Rh-.

Significance of Rh factor in transfusion

Blood transfusion is allowed for blood transfusion, which has the same values according to the Rhesus system. So, a recipient with a negative Rh factor will be approached only by donor blood of a negative index. Similarly, with a positive, but in critical cases, an infusion of blood with a negative Rh factor in small quantities, maximum 200 ml. With such a transfusion, incompatibility does not occur, but when infused into the blood with a negative Rhesus factor of red blood cells with a positive value, a defensive reaction of the immune system to the antigen D. When detecting foreign erythrocytes, the immune system begins to produce agglutinins (d, c, e) that damage Poured in erythrocytes, which entails severe consequences for the recipient organism. According to the Rhesus and ABO system, eight types of blood are distinguished.

Compatibility of blood

Blood transfusion is a procedure of blood transfusion, which is used to restore blood balance and blood circulation. Donor blood should be compatible for both the accessory systems and the recipient's blood. For a long time it was believed that there is a universal donor and universal recipient. At the moment, both of these concepts are already practically extracted from the medical system. However, in critical situations, in the absence of time and donor blood, an identical group and Rhesus factor is sometimes still used in small-volume transfusions, not more than 500 ml.

The blood of the first group and the negative Rh 0 (I) Rh- value belong to the universal donor, since its composition does not contain its own antigens. The fourth positive AB (IV) Rh + group is considered to be a universal recipient due to the presence of antigens A and B on the erythrocyte membrane. But, nevertheless, the transfusion procedure is tried with identical groups.

I blood group: compatibility chart

In case of transfusion, the I group with a negative Rh (0 (I) Rh-) can be a donor for all blood groups with a positive and negative Rh factor in case of emergency transfusion and, if necessary, a large amount to act as a donor for the I group with identical rhesus index.

For the recipient with the first blood group and the positive Rh factor, the donor blood may be the first positive or negative 0 (I) Rh - / + group. With the first blood group with a negative rhesus index, transfusion is performed only with the identical 0 (I) Rh- group.

Compatibility of the second group

The second negative group A (II) Rh- can become donor for the second and fourth with any exponent of rhesus. The second positive group A (II) Rh + is used as a donor only for the second and fourth AB (IV) Rh + with a positive Rh factor.

The recipient with the second positive group A (II) Rh + can receive the donor blood of the first 0 (I) Rh - / + and the second group A (II) Rh - / + with any Rhesus factor. If the recipient's blood is designated as a negative Rhesus A (II) Rh, the transfusion is performed with groups as for the second positive, only exceptionally negative Rhesus factor value.

Compatibility of the third group

As a donor third blood group with a positive Rh factor B (III) Rh +
It is used for transfusion to recipients with the third and fourth group with a positive rhesus index. The third negative group is compatible for donation with the third and fourth blood group, at any Rhesus factor value in the recipient.

The holders of the third positive group are transfused with donor blood of the first and third group with negative or positive rhesus. The third negative is characterized by compatibility with the third and fourth group with a negative Rh factor.

Compatibility of the fourth group

Donor blood of the fourth group with a positive Rh factor is suitable only for transfusion to recipients with identical group and rhesus index. The fourth negative is compatible for transfusion also only to the fourth group with negative and positive rhesus.

But the recipient with the fourth positive group AB (IV) Rh + is universal and perceives, with a positive rhesus value, absolutely all blood groups with any Rhesus values. With a negative Rhesus factor, transfusions use donor erythrocytes of all groups with negative Rhesus index only.

Risks of transfusion of incompatible groups

The main risk for blood transfusion is agglutination.

Agglutination is the process of gluing together the erythrocytes, which leads to their destruction when the blood enters the body with agglutinogen, to which the blood of the recipient has developed agglutinin. This means that agglutination occurs when blood is combined with the same antigens and agglutinins A and a, B and b. With this combination, the antibodies (a or b) produced for the missing antigen (A or B) destroy the donor red blood cells, resulting in their subsidence and subsequent hemolysis (decay). Blood is the main oxygen carrier for all cells of the body, therefore, after the decay of erythrocytes, a blood-shock shock forms, which can lead to severe consequences and even death. It is on the basis of such risks that great attention is paid to the blood group schemes compatible with each other.

The ABO and Rhesus system is the main one in the classification, but not the only one. Many other antigens are placed on the surface of the erythrocyte membrane, which currently participate in the selection of compatible donor blood. But, more and more private clinics additionally determine the presence or absence of a rare Kell antigen, with a positive value of which donor red blood cells are incompatible with any others.