Blood rh
Rh is the first two letters of mbth, a macaque. Randsteiner and other scientists found that rhesus monkeys and most human red blood cells have antigen substances of Rh blood group when doing animal experiments in 1940, hence the name. Anyone with Rh antigen (also known as D antigen) on red blood cells is called Rh negative. In this way, people who have found four main blood types of red blood cells, A, B, O and AB, are divided into Rh positive and RH negative respectively. With the continuous study of Rh blood group, it is considered that Rh blood group system may be the most complicated blood group in red blood cells. The discovery of Rh blood group plays a very important role in guiding blood transfusion more scientifically, further improving the experimental diagnosis level of hemolytic disease of newborn and maintaining the health of mother and baby. According to relevant data, Rh-positive blood group accounts for about 99.7% of the Han nationality and most ethnic groups in China, and some ethnic minorities account for about 90%. In some foreign nationalities, the proportion of people with Rh positive blood type is about 85%, among which the proportion of people with Rh negative blood type is about 15% among white people in Europe and America.
In China, RH-negative blood group only accounts for three to four thousandths. The ratio of RH negative type A, type B, type O and type AB is 3: 3: 3: 1.
RH-negative people can't accept the blood of RH-positive people, because the antigen in RH-positive blood will stimulate RH-negative people to produce RH antibodies. If RH positive blood is transfused again, it will lead to hemolytic transfusion reaction. However, RH-positive people can receive blood from RH-negative people.
There is a special antigen on human red blood cells, which is the same as that on rhesus monkey red blood cells. It is called "Rh" antigen. Everything containing this antigen is Rh positive, and everything without this antigen is Rh negative. Rh-negative people are more in white people, accounting for 15%, while the vast majority of Han people in China are Rh-positive, and Rh-negative people are less than 1%.
[Clinical significance]
1.Prevention of hemolytic transfusion reaction caused by Rh blood group system: Rh-negative patients can stimulate the body to produce anti-Rh antibodies if they receive Rh-positive blood, and hemolytic transfusion reaction will occur when they receive Rh-positive blood again. For example, if a Rh-negative woman gives birth to a Rh-positive fetus, the transfusion of Rh-positive blood will also cause hemolysis. Therefore, patients and blood donors who need blood transfusion should not only check ABO blood group, but also do Rh blood group identification to avoid this situation.
2. Neonatal hemolysis caused by Rh-positive red blood cells: After a Rh-negative mother gives birth to a Rh-positive fetus, if a certain number of fetal red blood cells enter the mother's body, it can stimulate the mother to produce anti-RH-positive antibodies. For example, when the mother is pregnant again and gives birth to a second child, this antibody can pass through the placenta, dissolve and destroy the fetal red blood cells, and cause hemolysis of the newborn. If pregnant women have received Rh-positive blood before, the first child may have neonatal hemolysis.
Rh blood group system, which contains six antigens, namely C, C, D, D, E, E, all red blood cells containing D antigen are RH positive, otherwise they are negative. Rh blood group has no natural antibodies, and its antibodies are mostly produced by blood transfusion (Rh-negative patients are given Rh-positive blood) or pregnancy (Rh-negative mothers are pregnant with Rh-positive fetuses), which has important clinical significance. Once antibodies are formed, if Rh-positive blood is reinfused, a serious transfusion reaction may occur. Neonatal hemolysis can occur when Rh-positive fetus is bred again.
Therefore, after RH-negative women lose RH-positive blood, antibodies are produced in the blood, so they can no longer have RH-positive children, otherwise it is difficult for babies to survive. There are also a large number of bilirubin produced by hemolysis of some surviving fetuses entering brain cells, causing neonatal central nerve cell pathological changes (called nuclear jaundice). Even if it survives, it will affect the intellectual development and sports ability of sick children.
If a woman does not lose RH-positive blood, she can give birth to her first child. This is because when the first child is pregnant, the amount of antibodies produced by pregnant women is not enough to cause fetal diseases. If the first child is RH positive, then you can't continue to have children in the future.
If the male is RH negative, don't have a second child if he has a RH positive child. However, men will not lose their fertility after receiving RH positive blood transfusion.
Remarks: RH and ABO blood groups should be tested during blood transfusion.
How do Rh(-) people protect themselves?
Please remember this principle: only transfusion of the same type is allowed, that is, patients with type A Rh(-) can only receive blood of type A Rh(-), and patients with type B Rh(-) can only receive blood of type B Rh(-). If you are sick or need blood transfusion during surgery, be sure to tell the doctor that you are Rh (-) blood type, so that the doctor can contact the city blood bank as soon as possible to organize the Rh(-) blood source you need. If you are an unmarried woman, please do a good job in family planning and avoid induced abortion. If you have a history of abortion or blood transfusion, you must go to the blood group room of the blood station for a predictive examination of hemolytic disease of the newborn during pregnancy to prevent the occurrence of hemolytic disease of the newborn in the future.
Do you know what the blood type worker has done for you?
In case of emergency, it is very important to provide homologous blood for Rh(-) patients in time. Blood group workers in blood stations take it as their responsibility to ensure the safety of blood transfusion for every Rh(-) patient, and make unremitting efforts to screen Rh(-) blood groups for tens of thousands of blood donors all the year round. Once Rh(-) blood is screened out, this bag of blood will be marked with special marks immediately and stored in the refrigerator at 4℃ for emergency use.
Is the blood transfusion supply of Rh(-) patients guaranteed?
Although blood transfusion workers have tried their best to prevent problems before they happen, Rh(-) patients may lack the same type of blood in an emergency, and the potential danger of life-threatening still exists. In fact, the way to solve this problem is simple: all Rh(-) patients are in the same boat, and they are always noble blood donors while becoming possible blood recipients, so that the lives of you and all Rh(-) patients will be guaranteed.
Some blood group antibodies are incomplete antibodies, and no agglutination can be seen after binding with the corresponding antigen cells. There are antibodies in serum, but they are not easy to find. 1945 anti-human globulin test is applied to blood group examination, which can detect incomplete antibodies. Since then, many blood group antigens have been discovered. Whenever a new antigen is found, it is necessary to determine the relationship between the antigen and the blood group that has been found, thus determining several blood group systems on human red blood cells. In addition, there are some antigens, either because of their high frequency in the population or because of their low frequency in the population, which can not be used for genetic analysis. Until their genetic relationship is clear, these antigens are temporarily called high-frequency antigens and low-frequency antigens, and their attribution needs to be further determined.
Erythrocyte blood group antigen
There are three kinds of protein in erythrocyte membrane: glycoprotein, simple protein and membrane contractile protein. Some red blood cell antigens protrude on the cell surface, like branches protruding from the ground, such as ABH antigen; Some are embedded in the cell membrane, such as Rh antigen. The part where antigen reacts specifically with antibody is called antigenic determinant. The chemical composition of blood group antigenic determinants is known, but most of them are unknown. Some blood types have soluble antigens in body fluids, which are called blood group substances. ABH and Lewis blood group substances isolated from human body are glycoproteins, that is, some sugar side chains are attached to the backbone of peptide chains and are specific determinants. The specific determinants of ABH and Lewis blood group substances are very similar, but a single sugar type or the same sugar in the sugar chain shows different specificity because of different positions. For example, the antigen specificity of A and B shows different specificity only when there are different sugars in the sugar chain. Epitope A is N- acetylgalactosamine at the end of sugar chain, while epitope B is D- galactose at the end of sugar chain.
Although the ABH antigenic determinant on red blood cells has the same sugar chain structure as that in body fluids, the connected skeletons are different. The sugar chains on red blood cells are bound to fatty acids through sphingosine instead of protein, so ABH antigen on red blood cells is glycolipid instead of glycoprotein.
The antigenic determinants of MN P and I blood groups are also carbohydrates. The determinant of Rh antigen may be protein, because the activity of Rh disappears immediately after red blood cells are treated with hydrosulfide, urea and protease.
Some blood group antibodies, such as anti-IH, anti-IA, anti-IB and anti-IP 1, only react with cells with I antigen and another antigen, but not with cells with only one antigen. It shows that these antigens are complex antigens with two specificities in one molecule.
Lewis blood group antigen is actually an antigen in plasma, and Lewis antigen on red blood cells is adsorbed from plasma. Although I antigen has soluble antigen in secretion, it does not exist in plasma. In addition, some blood types have soluble antigens in plasma, but not in secretions. Bg antigen is actually the antigen of white blood cells, which may fall off from white blood cells to plasma, and then adsorb from plasma to red blood cells, showing as the antigen of red blood cells. The antigens of Chido blood group and Rodger blood group are related to the fourth component (C4) of complement in plasma. By analyzing human C4 by electrophoresis, we can see three types: fast swimming (F); A slow swimmer; There are both fast and slow components (FS). People with only F component in plasma have Rodger antigen on red blood cells. Only S-component human red blood cells have Chido antigen. Chido and Rodger antigens are also found on human red blood cells with these two components.
The distribution of blood group antigens on red blood cells is different, some are dense and some are loose. The number of antigens determines the strength of antigens. Using rabbit anti-A and anti-B serum labeled with radioactive iodine to examine human red blood cells, the number of antigens on each red blood cell can be calculated according to the radioactive intensity on each cell.
At different stages of individual development, the strength of various blood group antigens is different. The reaction of ABO and Lewis antigens in newborns with corresponding antibodies is weaker than that in adults. Fetal red blood cells smaller than 10 cm can react with anti-P 1 serum, but the reaction intensity is weaker than that of adult red blood cells. The ability of neonatal red blood cells to absorb anti-I is almost the same as that of adult red blood cells, but the intensity of agglutination reaction is much weaker than that of adult red blood cells. But the agglutination with anti-I serum is stronger than that with adult red blood cells. The antigens of Yta and Xga are slightly weaker in neonatal red blood cells than in adult red blood cells, while the antigens of Rh, Kell, Duffy, Jk, MNSs, Di and Do are fully developed at birth. Chido blood group antigen can be detected in neonatal plasma, but not in red blood cells.
Blood group antibody antibody
It is immunoglobulin, but not all immunoglobulins are antibodies. Glycoprotein with antibody structure is immunoglobulin. Immunoglobulin is expressed by Ig. At present, it is found that there are five kinds of immunoglobulins in human beings, which are called IgG, IgM, IgA, IgD and IgE. There are only three kinds of immunoglobulins related to blood type, namely IgG, IgM and IgA.
According to whether there is detectable antigen stimulation in the body, there are so-called "natural antibodies" and "immune antibodies". Antibodies that appear in the body serum without antigen stimulation are called "natural antibodies"; Antibodies produced in serum after the body is stimulated by the same or different antigens are called immune antibodies.
There are two explanations for the production of "natural antibody": one is that there are "antigen sensitized" cells in the body, which can produce specific antibodies without antigen stimulation; Another explanation is that "natural antibodies" are heterogeneous lectins, and there are some substances similar to blood group antigens in the surrounding environment, as well as cross-reactive antibodies produced by the body after contacting these substances. For example, some bacteria contain antigens similar to human A and B antigens. When people inhale or swallow these bacteria, they produce cross-reactive antibodies.
Natural antibodies react strongly with corresponding antigen cells at low temperature. When the temperature exceeds 25℃, many natural antibodies lose their activity. Some "natural antibodies" have the ability to bind to complement, while others do not. For example, almost all Lewis blood group antibodies have the ability to bind to complement, while anti-M and anti-N have no ability to bind to complement. Natural antibodies are usually IgM immunoglobulins, but some natural antibodies are IgG immunoglobulins. If there is any "natural antibody" against Lea, M, N and K, it is IgG.
Immune antibody refers to the antibody produced by the body in the super immune state after being stimulated by the same or different antigens. Blood transfusion and pregnancy are the main reasons for producing allogeneic immune antibodies. People who have received vaccines, injected antiserum (diphtheria, tetanus antitoxin) and used pig stomach and pig liver extracts have increased anti-A and anti-B titers in serum, which is an example of immune antibodies caused by heterogeneous immunity. Immune anti-A and anti-B are different from "natural antibodies" in many ways.
Some antibodies can agglutinate with their corresponding antigen cells in saline medium, and such antibodies are called complete antibodies; Some antibodies can only bind (sensitize) their corresponding antigen cells in saline medium, but cannot agglutinate. This kind of antibody is called incomplete antibody. In order to make incomplete antibody agglutinate with its corresponding antigen cells, it is necessary to use other media, such as enzyme to treat red blood cells, or suspend red blood cells in macromolecular colloid, or with the help of antiglobulin serum. In fact, complete antibodies generally refer to IgM antibodies, and incomplete antibodies are mostly IgG antibodies. IgA mainly exists in secretions, but not in blood group antibodies.
Structure and function of ABO, MN and HLA blood groups
ABO blood group can be divided into four types: A, B, AB and O. Red blood cells containing A antigen and H antigen are called type A, and human serum of type A contains anti-B antibody. Red blood cells containing B antigen and H antigen are called type B, and human serum of type B contains anti-A antibody. Red blood cells contain A antigen, B antigen and H antigen, which are called AB type. There are no anti-A antibodies and anti-B antibodies in human serum of this blood type. Red blood cells only have H antigen, which is called O type. Human serum type O contains anti-A antibody and anti-B antibody.
◆ABO blood group
Substance exists not only in erythrocyte membrane, but also in saliva, gastric juice, semen and other secretions. 60% of Han people in China contain ABO blood group substances in saliva. The chemical essence of blood group substance refers to glycoprotein or glycolipid that constitutes blood group antigen, and the specificity of blood group mainly depends on the composition of blood group antigen sugar chain (that is, the determinant of blood group antigen is on the sugar chain). The chemical structure difference of blood group antigens A, B and H3 is only 1 monosaccharide at the end of sugar chain. The sugar chain end of A antigen is N- acetylgalactose, while the sugar chain end of B antigen is galactose. Compared with A and B antigens, the sugar chain end of H antigen is less 1 galactose or N- acetylgalactose. 198 1 year, someone has used green coffee bean enzyme (galactosidase) to act on B-type red blood cells to cut off galactose on B antigen, thus successfully transforming B-type into O-type.
E.von Dungeon and L. Hillsfeld found the subtype of blood group A in 19 1 1. They saw that red blood cells of different A-type people had different agglutination intensity with anti-A serum, and there was also an antibody in weak A-type human serum that could agglutinate with strong A-type red blood cells. According to this, it is considered that type A has subtypes; Subtypes A 1 and A2. Type A 1. Red blood cells react strongly with anti-A serum (from people of type B or O), while type A2 red blood cells react weakly with anti-A serum. In addition to anti-B, some A2 people have irregular anti-A 1. There are two kinds of antibodies in human serum of type B: anti-A and anti-A 1. Anti-A can react with A 1 and A2 cells. Anti-A 1 only reacts with A 1 cells. There are two antigens a and A 1 on red blood cells of type A 1. There is only antigen A on A2 cells. Type AB can also be divided into subtypes A 1B and A2B. There are some other subtypes.
◆MN blood group
Another blood group antigen on the erythrocyte membrane is called MN antigen, which is glycophorin A on the erythrocyte membrane. Two bands, PAS- 1 and PAS-2, were displayed on the SOS gel electrophoresis map, and glycophorin A was their dimer. It is known that glycophorin A consists of 13 1 amino acids, and its primary structure has been determined (Figure 2). The peptide chain of glycophorin A has a three-stage structure, and the amino acids in the middle 73 ~ 92 are hydrophobic peptide chains, which can pass through the membrane lipid layer. N-terminal peptide chain is located outside the membrane, which is related to blood group activity. There are 15 O- glycoside sugar chains and 1n- glycoside sugar chains in this peptide chain, and the sialic acid in the sugar chains accounts for more than half of all sialic acid on the erythrocyte membrane. C-terminal peptide chain is located in the membrane and contains more acidic amino acids.
MN antigen consists of M antigen and N antigen. If neuraminidase is used to cut 1 sialic acid (N- acetylneuraminic acid) from M antigen, it is N antigen, and if one sialic acid is cut off, the antigenicity will be completely lost. The antigenicity of MN antigen is also related to the amino group in the peptide chain. If the amino group is protected by acetyl group, it will lose its antigenicity.
◆ Leukocyte blood group -HLA
HLA is the most important human leukocyte antigen. Compared with red blood cell blood group, people know leukocyte antigen later. The first human leukocyte antigen Mac was discovered by French scientist J. Dorset in 1958. HLA is the abbreviation of human leukocyte antigen. It has been found that HLA antigens exceed 144 and are divided into seven series: A, B, C, D, DR, DQ and DP7. HLA also exists on other cell surfaces.
HLA antigen is a glycoprotein (containing 9% sugar), and its molecular structure is very similar to immunoglobulin (Figure 3). HLA molecule consists of four peptide chains (including two light chains and two heavy chains), and the heavy chain is connected with two sugar chains. HLA molecules are partially embedded in the bilayer of cell membrane, and the part inserted into the membrane is equivalent to the Fc segment of immunoglobulin IgG, and the light chain is β-microglobulin. Because of the similarity of molecular structure, HLA is closely related to the immune defense system with defensive function.
In addition, HLA, like red blood cell blood type, is controlled by genetic laws. The gene determining HLA type is on chromosome 6. Everyone can get a set of chromosomes from their parents, so one person can find out 5 ~ 10 types of white blood cells in five series of A, B, C, D and DR at the same time, so there are hundreds of millions of white blood cell types. It is difficult to find two people with identical HLA but no blood relationship. However, the probability that HLA is completely the same or completely different between siblings is always 1/4. Therefore, HLA determination is the most powerful tool for forensic identification of kinship.