TABLE 2. The blood groups with their genotypes and their constituent agglutinogens and agglutinins
| Genotypes | Blood groups | Agglutinogens | Agglutinins |
| 00 | 0 (I) | - | Anti-A and Anti-B |
| 0A or AA | A (II) | A | Anti-B |
| 0B or BB | B (III) | B | Anti-A |
| AB | AB(IV) | A and B | - |
The agglutinins are gamma-globulins, as are other antibodies, and are produced by the same cells that produce antibodies to any other antigens. Most of them are Ig G and M immunoglobulin molecules.
But why are these agglutinins produced in individuals who do not have the antigenic substances in their red blood cells? The answer to this seems to be that small amounts of group A and B antigens enter the body in the food, in bacteria, and in other ways, and these substances initiate the development of the anti-A or anti-B agglutinins. One of the reasons for believing this is that injection of group A or group B antigen into a recipient having another blood type causes a typical immune response with formation of greater quantities of agglutinins than ever. Also, the newborn baby has few if any agglutinins showing that agglutinin formation occurs almost entirely after birth.
Agglutinins are designated by letters б- and в-. Blood of one individual can not have similar agglutinogens and agglutinins. There are also hemolysines in plasma and serum (they are designated like agglutinins). One can see conflict at blood hemotransfusions at meeting of one-named agglutinogens and hemolysines (they act at 37-40°C). At room temperature, if one-named agglutinogens and agglutinins meet each other agglutination reaction occurs –the criterium of group characteristic. So, antigen-antibody interaction at room temperature is known as agglutination, at increased one – hemolysis. Both variants are accompanied by cells clumping.
High resistance to temperature, blood preservation terms are the characteristic of all agglutinogens. That’s why they contain practrically in all tissues of given organism and its fluids. That’s why agglutinogens content is essential to be known, when blood is received from donor with its further usage for transmission. On the contrary, agglutinins are unstable comparatively to agglutinogens and they are easily destroyed while contact with side surface, while temperature changing. That’s why they are not important in donor blood, but their determining is quite essential in recipient blood.
A donor is a person who gives blood, and a recipient is a person who receives blood. Usually a donor can give blood to a recipient if they both have the same blood type. For example, a person with type A blood could donate to another person with type A blood. There would be no ABO transfusion reaction because the recipient has no antibodies against the type A antigen. On the other hand, if type A blood were donated to a person with type B blood, a transfusion reaction would occur because the person with type B blood has antibodies against the type A antigen, and agglutination would result.
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Historically, people with type O blood have been called universal donors because they usually can give blood to the other ABO blood types without causing an ABO transfusion reaction. Their erythrocytes have no ABO surface antigens and therefore do not react with the recipient's A or B antibodies. For example, if type O blood is given to a person with type A blood, the type O erythrocytes do not react with the type B antibodies in the recipient's blood. In a similar fashion, if type O blood is given to a person with type B blood, there would be no reaction with the recipient's type A antibodies.
It should be noted, however, that the term universal donor is misleading. In two circumstances transfusion of type O blood can produce a transfusion reaction. First, mismatching blood groups other than the ABO blood group can cause a transfusion reaction. To reduce the likelihood of a transfusion reaction, all the blood groups must be correctly matched. Second, antibodies in the blood of the donor can react with antigens on the erythrocytes in the blood of the donor can react with antigens on the erythrocytes in the blood of the recipient. For example, type O blood has type A and B antibodies. If type O blood is transfused into a person with type A blood, the A antibodies (in the type O blood) react against the A antigens (on the erythrocytes in the type A blood). Usually such reactions are not serious because the antibodies in the donor's blood are diluted in the blood of the recipient, and few reactions take place. Because type O blood causes transfusion reactions in these situations, however, it is given to a person with another blood type only in life-or-death conditions.
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Historically, people with type AB blood were called universal recipients. People with type AB blood were called universal recipients because they could receive type A, B, AB, or O blood with little likelihood of a transfusion reaction. Type AB blood does not have antibodies against type A or B antigens. Transfusion of these antigens in type A, B, or AB blood does not therefore cause a transfusion reaction in a person with type AB blood. The term is misleading, however, for two reasons. First, other blood groups can cause a transfusion reaction. Second, antibodies in the donor's blood can cause a transfusion reaction. For example, type O blood contains A and B antibodies that can react against the A and B antigens in type AB blood.
Rh-SYSTEM
Rhesus-system was discovered in the middle of last century. Rh blood group so named because it was first studied in the rhesus monkey. 85 per cent of people have agglutinogen of this system (Rh-rhesus) and these people are called rhesus-positive. 15 per cent of people have no this antigen and correspondingly they are known as rhesus-negative. 88% of black people in the United States are Rh-positive. The ABO blood type and the Rh blood type usually are designated together. For example, a person designated as A positive is type A in the ABO blood group and Rh-positive. The rarest combination in the United States is AB negative, which occurs in less than 1% of all Americans.
Rh-system is rather complicated, it includes more than 40 antigens. This factor is inherited. Antibodies against the Rh antigens do not develop unless the Rh-negative person is exposed to Rh-positive erythrocytes. This can occur through a transfusion or by the transfer of blood across the placenta to a mother from her fetus. When a Rh-negative person receives a transfusion of Rh-positive blood, the recipient becomes sensitized to the Rh antigens and produces Rh antibodies. If the Rh-negative person is unfortunate enough to receive a second transfusion of Rh-positive blood after becoming sensitized, a transfusion reaction results.
Rh incompatibility can pose a major problem in some pregnancies, when the mother is Rh-negative and the fetus is Rh-positive. One can say about Rh-conflict (if mother is Rh-negative, father is Rh-positive than fetus will be Rh-positive as well) and the newborns hemolytic disease.
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1. Before or during delivery. Rh-positive erythrocytes from the fetus enter the blood of an Rh-negative woman through a tear in the placenta.
2. The mother is sensitized to the Rh antigen and produces Rh antibodies. In the first pregnancy, there is often no problem. The leakage of fetal blood is usually the result of a tear through placenta that takes place either late in the pregnancy or during delivery. Thus there is not enough time for the mother to produce sufficient numbers of Rh antibodies to harm the fetus.
3. During a subsequent pregnancy with an Rh-positive fetus, Rh-positive erythrocytes cross the placenta, enter the maternal circulation, and stimulate the mother to produce antibodies against the Rh antigen. Antibody production is rapid because the mother has been sensitized to the Rh antigen. The Rh antibodies from the mother cross the placenta, causing agglutination and hemolysis of fetal erythrocytes, and hemolytic disease of the newborn (HDN) develops. It can be fatal for the fetus.
Prevention of hemolytic disease of the newborn is often possible if the Rh-negative woman is given an injection of a specific type of antibody preparation called anti-Rh0(D) immune globulin Rh0GAM). The injection can be given during the pregnancy, before delivery, or immediately after each delivery, miscarriage, or abortion. The injection contains antibodies against Rh antigens. The injected antibodies bind to the Rh antigens of any fetal erythrocytes that may have entered the mother's blood. This treatment inactivates the fetal Rh antigens and prevents sensitization of the mother.
If HDN develops, treatment consists of slowly removing the blood of the fetus or newborn and replacing it with RH-negative blood. The newborn's skin is also exposed to fluorescent light because it helps to break down bilirubin in the blood as the blood flows through the skin. The bilirubin is derived from the hemoglobin released from ruptured erythrocytes. High levels of bilirubin are toxic to the nervous system and can cause destruction of brain tissue.
Other antigen systems are more seldom (Luteran, Daffi, Kell-Kellano, MNS et al.). Scientists tell nowadays about 500 antigens only on erythrocytic membrane. If to add others to them, then their amount will predominate number of all residents on the Earth. With other worlds, every person has his or her own blood group that is quite essential to know and to use in clinical practice.
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