ABO blood group
(immunology) An immunologically distinct, genetically determined group of human erythrocyte antigens represented by two blood factors (A and B) and four blood types (A, B, AB, and O).
|
Results for blood type
|
On this page:
|
(immunology) An immunologically distinct, genetically determined group of human erythrocyte antigens represented by two blood factors (A and B) and four blood types (A, B, AB, and O).
Blood has two main components: serum and cells. In 1900 Karl Landsteiner, a physician at the University of Vienna, Austria, noted that the sera of some individuals caused the red cells of others to agglutinate. This observation led to the discovery of the ABO blood group system, for which Landsteiner received the Nobel Prize. Based on the reactions between the red blood cells and the sera, he was able to divide individuals into three groups: A, B, and O. Two years later, two of his students discovered the fourth and rarest type, namely AB.
Antigens and Antibodies
To understand blood typing, it is necessary to define antigen and antibody. An antigen is a substance, usually a protein or a glycoprotein, which, when injected into a human (or other organism) that does not have the antigen, will cause an antibody to be produced. Antibodies are a specific type of immune-system proteins known as immunoglobulins, whose role is to fight infections by binding themselves to antigens. In the case of the ABO blood groups, the antigens are present on the surface of the red blood cell, while the antibodies are in the serum. These antibodies are unique to the ABO system and are termed "naturally occurring antibodies." The table shows the relationships between blood types and antibodies.
Table 1
| RELATIONSHIPS BETWEEN BLOOD TYPES AND ANTIBODIES | ||||
| Blood Type | Antigens on Red Blood Cell | Can Donate Blood To | Antibodies in Serum | Can Receive Blood From |
| A | A | A, AB | Anti-B | A, O |
| B | B | B, AB | Anti-A | B, O |
| AB | A and B | AB | None | AB, O |
| O | None | A, B, AB, O | Anti-A and anti-B | O |
This aspect of the ABO blood group system is very important in transfusion. Blood group O individuals are said to be universal donors, because their blood can be used for transfusion in individuals who have any one of the four blood types. On the other hand, individuals with blood type A can only donate to either type A or type AB, and individuals with blood type B can only donate to B or AB types. AB individuals can only donate to type AB. However, before any transfusions, donor blood is mixed with serum from the recipient (a process called cross matching) to ensure that no agglutination will occur after transfusion.
Multiple Alleles
The genetic basis of the ABO blood group system is an example of multiple alleles. There are three alleles, A, B, and O, at the ABO locus on chromosome 9. The expression of the O allele is recessive to that of A and B, which are said to be co-dominant. Thus, the genotypes AO and AA express blood type A, BO and BB express blood type B, AB expresses blood type AB, and OO expresses blood type O. In the past, ABO blood group typing was used extensively both in forensic cases as well as for paternity testing. More recently, DNA testing, which is much more informative, has superseded these tests.
The ABO blood group substances are glycoproteins, the basic molecule of which is known as the H substance. This H substance is present in unmodified form in individuals with blood type O. Adding extra sugar molecules to the H substance produces the A and B substances. The frequency of the ABO blood types varies widely across the globe. For example, blood group B has a frequency of 25 percent in Asians, 17 percent in Africans, but only 8 percent in Caucasians. The frequency of blood group O in Europe increases as one travels from southern to northern countries.
Alleles at a locus independent of the ABO blood group locus, known as the secretor locus, determine an individual's ability to secrete the ABO blood group substances in saliva and other body fluids. There are two genes, Se and se, where Se is dominant to se. In other words, an individual with at least one Se gene is a secretor. Approximately 77 percent of Europeans are secretors. This frequency is rarely less than 50 percent and sometimes as high as 100 percent in other populations.
An interesting aspect of the ABO blood groups is their association with disease. Among individuals with stomach and peptic ulcers, there is an excess of type O individuals, whereas among those with cancer of the stomach, there is an excess of type A individuals. Not all type O individuals have an increased risk for peptic or stomach ulcers, however. If type O individuals are secretors, they are protected against ulceration, whereas non-secretors have a two-fold increased risk. Thus the presence of ABO blood group substances act as a protective agent against the development of stomach and peptic ulcers.
The Rh System
The second most important blood group in humans is the Rhesus (Rh) system. Landsteiner and Wiener discovered the Rh blood group in 1940. They found that when they injected rabbits with Rhesus monkey blood; the rabbits produced antibodies against the Rhesus red cells. These antibodies reacted with red blood cells taken from 85 percent of Caucasians in New York City, who were thus said to be Rh positive, while the remaining 15 percent were Rh negative.
One year earlier (1939), Levine and Stetson published a paper describing the mother of a stillborn infant who had a severe reaction when transfused with her husband's blood. They tested the woman's serum and found that it reacted with 77 percent of blood donors. They postulated that the mother had been exposed to blood from her fetus and produced an antibody that reacted with it. The same antigen was present in the baby's father, explaining the woman's reaction to his blood. Their conclusion was correct, and later they realized that they had discovered the same antigen (Rh) that was discovered in the following year. The antibody found in the mother of the stillborn child was shown to be identical to the anti-Rh antibody produced in the rabbit by Landsteiner and Wiener.
The Rh blood group system is the major cause of hemolytic anemia in the newborn. A fetus who is Rh+ and whose mother is Rh− is at high risk for this disorder, because the mother will produce antibodies against the fetal antigen. The first such fetus is usually not at risk since the fetal cells do not enter the mother's circulation until the time of birth. Only at this time does the mother produce anti-Rh+ antibodies. This complicates future pregnancies, because her antibodies will enter the fetal circulation system and react with fetal blood, causing hemolysis.
A treatment for Rh− women at risk to have an Rh+ fetus is now widely used. Anti-Rh+ antibody is injected into the mother soon after her first delivery. This antibody coats the fetal Rh+ cells in the mother's circulation, which prevents them from causing antibody production in the mother and, therefore, her next child will not be at risk for hemolytic anemia.
The precise genetics of the complex Rh system has been in dispute since the early discoveries. The Rh blood group system is, in fact, much more complex than simply Rh+ and Rh−. There are two genes, one of which has four possible alleles, giving six antigens of which five are commonly tested. The first is D, which is the dominant gene that determines whether one is Rh+ or Rh−. Individuals with genotypes DD and Dd are Rh+ and those who are dd are Rh−. The DD and Dd genotypes cannot be distinguished from one another, since there is no "anti-d" antibody. The remaining four antigens are C, c, E, and e. The Rh locus is on the short arm of chromosome 1 and consists of two tandem genes. The first, RHCE, codes for non-RhD proteins while the second codes for the RhD protein. The Rh polypeptide has been sequenced. It contains 417 amino acids. Thus the molecular genetics conferring different antigenic Rh types is now clear.
Bibliography
Cavalli-Sforza, L. L., and W. F. Bodmer. The Genetics of Human Populations. San Francisco: W. H. Freeman and Company, 1971.
Huang, Cheng-Han, Philip Z. Liu, and Jeffrey G. Cheng. "Molecular Biology and Genetics of the Rh Blood Group System." Seminars in Hematology 37, no. 2 (2000): 150-165.
Race, R. R., and Ruth Sanger. Blood Groups in Man, 6th ed. Oxford, U.K.: Blackwell Scientific Publications, 1975.
"Blood Types." Indiana State University. http://www.indstate.edu/thcme/mwking/abo-bloodgroups.gif.
—P. Michael Conneally
One of many groups into which a person's blood can be categorized, based on the presence or absence of specific antigens in the blood. Blood type is inherited.
1. blood group.
2. the phenotype of an individual with respect to a blood group system.
A blood type (also called a blood group) is a classification of blood based on the presence or absence of inherited antigenic substances on the surface of red blood cells (RBCs). These antigens may be proteins, carbohydrates, glycoproteins or glycolipids, depending on the blood group system, and some of these antigens are also present on the surface of other types of cells of various tissues. Several of these red blood cell surface antigens, that stem from one allele (or very closely linked genes), collectively form a blood group system.
The harmful immunological effects of mismatched blood transfusions are much more likely to involve components of the ABO blood group system or the RhD antigen (also known as the Rhesus factor or Rhesus D antigen) of the Rhesus blood group system than components any of the other blood group systems; hence, in the routine preparation of blood for transfusion in a blood bank, the presence or absence the immunogenic blood group antigens, the A antigen, the B antigen and the RhD antigen are always determined for all recipient and donor blood. This identifies the ABO blood group and the RhD antigen status, which are both stated in the common terminology A positive, O negative, etc., where a capital letter (A, B or O) refers to the ABO blood group, and positive or negative refers to the presence or absence of the RhD antigen of the Rhesus blood group system. In the routine preparation and selection of donor blood for blood transfusion, it is not necessary to determine the status of any other blood group antigens or antibodies, because antibody screening and cross-matching (or computer aided simulated cross-matching) prior to transfusion detects if there are any other blood group incompatibilities between potential donor blood and intended recipients.
If an individual is exposed to a blood group antigen that is not recognised as self, the immune system will produce antibodies that can specifically bind to that particular blood group antigen and an immunological memory against that antigen is formed. The individual will have become sensitized to that blood group antigen. These antibodies can bind to antigens on the surface of transfused red blood cells (or other tissue cells) often leading to destruction of the cells by recruitment of other components of the immune system. When IgM antibodies bind to the transfused cells, the transfused cells can clump. It is vital that compatible blood is selected for transfusions and that compatible tissue is selected for organ transplantation. Transfusion reactions involving minor antigens or weak antibodies may lead to minor problems. However, more serious incompatibilities can lead to a more vigorous immune response with massive RBC destruction, low blood pressure, and even death.
Blood types are inherited and represent contributions from both parents. Often, pregnant women carry a fetus with a different blood type from their own, and sometimes the mother forms antibodies against the red blood cells of the fetus, which causes hemolysis of fetal RBCs, and which in turn can lead to low fetal blood counts, a condition known as hemolytic disease of the newborn. Some blood types are associated with inheritance of other diseases; for example, the Kell antigen is associated with McLeod syndrome.[1] Certain blood types may affect susceptibility to infections, an example being the resistance to specific malaria species seen in individuals lacking the Duffy antigen.[2]The Duffy antigen, presumedly as a result of natural selection, is less common in ethnic groups from areas with a high incidence of malaria.[3]
The two most significant blood group systems were discovered during early experiments with blood transfusion: the ABO group in 1901[4] and the Rhesus group in 1937.[5] Development of the Coombs test in 1945,[6] the advent of transfusion medicine, and the understanding of hemolytic disease of the newborn led to discovery of more blood groups. Today, a total of 29 human blood group systems are recognized by the International Society of Blood Transfusion (ISBT).[7] A complete blood type would describe a full set of 29 substances on the surface of RBCs, and an individual's blood type is one of the many possible combinations of blood group antigens. Across the 29 blood groups, over 600 different blood group antigens have been found,[8] but many of these are very rare or are mainly found in certain ethnic groups. Almost always, an individual has the same blood group for life; but very rarely, an individual's blood type changes through addition or suppression of an antigen in infection, malignancy or autoimmune disease.[9] Blood types have been used in forensic science and in paternity testing, but both of these uses are being replaced by DNA analysis, which provides greater certitude.
The ABO system is the most important blood group system in human blood transfusion. The associated anti-A antibodies and anti-B antibodies are usually "Immunoglobulin M", abbreviated IgM, antibodies. ABO IgM antibodies are produced in the first years of life by sensitization to environmental substances such as food, bacteria and viruses. The "O" in ABO is often called "0" (zero/null) in other languages.[10]
| Phenotype | Genotype |
|---|---|
| A | AA or AO |
| B | BB or BO |
| AB | AB |
| O | OO |
The Rhesus system is the second most significant blood group system in human blood transfusion. The most significant Rhesus antigen is the RhD antigen because it is the most immunogenic of the five main rhesus antigens. It is common for RhD negative individuals not to have any anti-RhD IgG or IgM antibodies, because anti-RhD antibodies are not usually produced by sensitization against environmental substances. However, RhD negative individuals can produce IgG anti-RhD antibodies following a sensitizing event: possibly a fetomaternal transfusion of blood from a fetus in pregnancy or occasionally a blood transfusion with RhD positive RBCs.
| Population | O+ | A+ | B+ | AB+ | O− | A− | B− | AB− |
|---|---|---|---|---|---|---|---|---|
| Australia[11] | 40% | 31% | 8% | 2% | 9% | 7% | 2% | 1% |
| Belgium[12] | 38.1% | 34% | 8.5% | 4.1% | 7% | 6% | 1.5% | 0.8% |
| Canada[13] | 39% | 36% | 7.6% | 2.5% | 7% | 7% | 1.4% | 0.5% |
| Denmark[14] | 35% | 37% | 8% | 4% | 6% | 7% | 2% | 1% |
| Finland[15] | 27% | 38% | 15% | 7% | 4% | 6% | 2% | 1% |
| France[16] | 36% | 37% | 9% | 3% | 6% | 7% | 1% | 1% |
| Hong Kong, China[17] | 40% | 26% | 27% | 7% | <0.3% | <0.3% | <0.3% | <0.3% |
| Korea, South[18] | 27.4% | 34.4% | 26.8% | 11.2% | 0.1% | 0.1% | 0.1% | 0.05% |
| Netherlands[19] | 39.5% | 35% | 6.7% | 2.5% | 7.5% | 7% | 1.3% | 0.5% |
| Poland[20] | 31% | 32% | 15% | 7% | 6% | 6% | 2% | 1% |
| Sweden[21] | 32% | 37% | 10% | 5% | 6% | 7% | 2% | 1% |
| UK[22] | 37% | 35% | 8% | 3% | 7% | 6% | 2% | 1% |
| USA[23] | 38% | 34% | 9% | 3% | 7% | 6% | 2% | 1% |
The International Society of Blood Transfusion currently recognizes 29 blood group systems (including the ABO and Rh systems).[7] Thus, in addition to the ABO antigens and Rhesus antigens, many other antigens are expressed on the RBC surface membrane. For example, an individual can be AB RhD positive, and at the same time M and N positive (MNS system), K positive (Kell system), Lea or Leb negative (Lewis system), and so on, being positive or negative for each blood group system antigen. Many of the blood group systems were named after the patients in whom the corresponding antibodies were initially encountered.
Transfusion medicine is a specialized branch of hematology that is concerned with the study of blood groups, along with the work of a blood bank to provide a transfusion service for blood and other blood products. Across the world, blood products must be prescribed by a medical doctor (licensed physician or surgeon) in a similar way as medicines. In the USA, blood products are tightly regulated by the Food and Drug Administration.
Much of the routine work of a blood bank involves testing blood from both donors and recipients to ensure that every individual recipient is given blood that is compatible and is as safe as possible. If a unit of incompatible blood is transfused between a donor and recipient, a severe acute immunological reaction, hemolysis (RBC destruction), renal failure and shock are likely to occur, and death is a possibility. Antibodies can be highly active and can attack RBCs and bind components of the complement system to cause massive hemolysis of the transfused blood.
Patients should ideally receive their own blood or type-specific blood products to minimize the chance of a transfusion reaction. Risks can be further reduced by cross-matching blood, but this may be skipped when blood is required for an emergency. Cross-matching involves mixing a sample of the recipient's blood with a sample of the donor's blood and checking to see if the mixture agglutinates, or forms clumps. If agglutination is not obvious by direct vision, blood bank technicians usually check for agglutination with a microscope. If agglutination occurs, that particular donor's blood cannot be transfused to that particular recipient. In a blood bank it is vital that all blood specimens are correctly identified, so labeling has been standardized using a barcode system known as ISBT 128.
The blood group may be included on identification tags or on tattoos worn by military personel, in case they should need an emergency blood transfusion. Frontline German Waffen-SS had such tattoos during World War II and ironically this was an easy form of SS identification.[24]
Rare blood types can cause supply problems for blood banks and hospitals. For example Duffy-negative blood occurs much more frequently in people of African origin,[25] and the rarity of this blood type in the rest of the population can result in a shortage of Duffy-negative blood for patients of African ethnicity. Similarly for RhD negative people, there is a risk associated with travelling to parts of the world where supplies of RhD negative blood are rare, particularly East Asia, where blood services may endeavor to encourage Westerners to donate blood.[26]
A pregnant woman can make IgG blood group antibodies if her fetus has a blood group antigen that she does not have. This can happen if some of the fetus' blood cells pass into the mother's blood circulation (e.g. a small fetomaternal hemorrhage at the time of childbirth or obstetric intervention), or sometimes after a therapeutic blood transfusion. This can cause Rh disease or other forms of hemolytic disease of the newborn (HDN) in the current pregnancy and/or subsequent pregnancies. If a pregnant woman is known to have anti-RhD antibodies, the RhD blood type of a fetus can be tested by analysis of fetal DNA in maternal plasma to assess the risk to the fetus of Rh disease.[27] Antibodies associated with some blood groups can cause severe HDN, others can only cause mild HDN and others are not known to cause HDN.
In order to provide maximum benefit from each blood donation and to extend shelf-life, blood
banks fractionate some whole blood into several products. The most common of these
products are packed RBCs,
Units of packed red cells are made by removing as much of the plasma as possible from whole blood units.
| Recipient[1] | Donor[1] | |||||||
|---|---|---|---|---|---|---|---|---|
| O- | O+ | A- | A+ | B- | B+ | AB- | AB+ | |
| O- | O- | |||||||
| O+ | O- | O+ | ||||||
| A- | O- | A- | ||||||
| A+ | O- | O+ | A- | A+ | ||||
| B- | O- | B- | ||||||
| B+ | O- | O+ | B- | B+ | ||||
| AB- | O- | A- | B- | AB- | ||||
| AB+ | O- | O+ | A- | A+ | B- | B+ | AB- | AB+ |
Table note
1. Assumes absence of any atypical antibodies that would cause an incompatibility between donor and recipient blood
A RhD negative patient who does not have any anti-RhD antibodies (never being previously sensitized to RhD positive RBCs) can receive a transfusion of RhD positive blood once, but this would cause sensitization to the RhD antigen, and a female patient would become at risk for hemolytic disease of the newborn. If a RhD negative patient has developed anti-RhD antibodies, a subsequent exposure to RhD positive blood would lead to a potentially dangerous transfusion reaction. RhD positive blood should never be given to RhD negative women of childbearing age or to patients with RhD antibodies, so blood banks must conserve Rhesus negative blood for these patients. In extreme circumstances, such as for a major bleed when stocks of RhD negative blood units are very low at the blood bank, RhD positive blood might be given to RhD negative females above child-bearing age or to Rh negative males, providing that they did not have anti-RhD antibodies, to conserve RhD negative blood stock in the blood bank.
The converse is not true; RhD positive patients do not react to RhD negative blood.
Donor-recipient compatibility for
| Recipient | Donor[1] | |||
|---|---|---|---|---|
| O | A | B | AB | |
| AB | AB | |||
| A | A | AB | ||
| B | B | AB | ||
| O | O | A | B | AB |
Table note
1. Assumes absence of strong atypical antibodies in donor plasma
Rhesus D antibodies are uncommon, so generally neither RhD negative nor RhD positive blood contain anti-RhD antibodies. If a potential donor is found to have anti-RhD antibodies or any strong atypical blood group antibody by antibody screening in the blood bank, they would not be accepted as a donor; therefore, all donor blood plasma issued by a blood bank can be expected to be free of RhD antibodies and free of other atypical antibodies. Donor plasma issued from a blood bank would be suitable for a recipient who may be RhD positive or RhD negative, as long as blood plasma and the recipient are ABO compatible.
With regard to transfusions of whole blood or packed red blood cells, individuals with type O negative blood are often called universal donors, and those with type AB positive blood are called universal recipients. Although blood donors with particularly strong anti-A, anti-B or any atypical blood group antibody are excluded from blood donation, the terms universal donor and universal recipient are an over-simplification, because they only consider possible reactions of the recipient's anti-A and anti-B antibodies to transfused red blood cells, and also possible sensitisation to RhD antigens. The possible reactions of anti-A and anti-B antibodies present in the transfused blood to the recipients RBCs are not considered, because a relatively small volume of plasma containing antibodies is transfused.
By way of example; considering the transfusion of O RhD negative blood (universal donor blood) into a recipient of blood group A RhD positive, an immune reaction between the recipient's anti-B antibodies and the transfused RBCs is not anticipated. However, the relatively small amount of plasma in the transfused blood contains anti-A antibodies, which could react with the A antigens on the surface of the recipients RBCs, but a significant reaction is unlikely because of the dilution factors. Rhesus D sensitisization is not anticipated.
Additionally, red blood cell surface antigens other than A, B and Rh D, might cause adverse reactions and sensitization, if they can bind to the corresponding antibodies to generate an immune response. Transfusions are further complicated because platelets and white blood cells (WBCs) have their own systems of surface antigens, and sensitization to platelet or WBC antigens can occur as a result of transfusion.
With regard to transfusions of
In April 2007 a method was discovered to convert blood types A, B, and AB to O; the method used enzymes.[30][31]
The Japanese blood type theory of personality is a popular belief that a person's ABO blood type is predictive of their personality, character, and compatibility with others, according to books by Masahiko Nomi. This belief has carried over to a certain extent in other parts of East Asia such as South Korea and Taiwan. In Japan, asking someone their blood type is considered as normal as asking their astrological sign. It is also common for Japanese-made video games (especially role-playing games) and manga series to include blood type with character descriptions.
The blood type diet is an American system whereby people seek improved health by modifying their food intake and lifestyle according to their ABO blood group and secretor status.[32] This system includes some reference to differences in personality, but not to the extent of the Japanese theory.
| Hemolytic disease of the newborn (HDN) |
|---|
| ABO HDN • Anti-Kell HDN • Rhesus c HDN • Rhesus D HDN • Rhesus E HDN |
| Transfusion medicine | |
|---|---|
| General concepts | Apheresis (Plasmapheresis, Plateletpheresis, Leukapheresis) - Blood transfusion - Coombs test - Cross-matching - Exchange transfusion - International Society of Blood Transfusion - Intraoperative blood salvage - ISBT 128 - Transfusion reactions |
| Human blood group systems - Blood type | ABO - Chido-Rodgers - Colton - Cromer - Diego - Dombrock - Duffy - Gerbich - GIL - Hh - Ii - Indian - JMH - Kell (Xk) - Kidd - Knops - Landsteiner-Weiner - Lewis - Lutheran - MNS - OK - P - Raph - Rh - Scianna - T-Tn - Xg - Yt |
| Blood products | Blood donation -
Blood substitutes - Cryoprecipitate -
Platelets - |
This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)
Join the WikiAnswers Q&A community. Post a question or answer questions about "blood type" at WikiAnswers.
Copyrights:
![]() | Sci-Tech Dictionary. McGraw-Hill Dictionary of Scientific and Technical Terms. Copyright © 2003, 1994, 1989, 1984, 1978, 1976, 1974 by McGraw-Hill Companies, Inc. All rights reserved. Read more | |
![]() | Genetics Encyclopedia. Genetics. Copyright © 2003 by The Gale Group, Inc. All rights reserved. Read more | |
![]() | Health Dictionary. The New Dictionary of Cultural Literacy, Third Edition Edited by E.D. Hirsch, Jr., Joseph F. Kett, and James Trefil. Copyright © 2002 by Houghton Mifflin Company. Published by Houghton Mifflin. All rights reserved. Read more | |
![]() | Veterinary Dictionary. Saunders Comprehensive Veterinary Dictionary 3rd Edition. Copyright © 2007 by D.C. Blood, V.P. Studdert and C.C. Gay, Elsevier. All rights reserved. Read more | |
![]() | Wikipedia. This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Blood type". Read more |
Mentioned In: