Blood type
Blood group redirects here.
A total of 29
human blood group systems are recognized by the
International Society of Blood Transfusion (ISBT). Each
blood group is represented by a substance on the surface of
red blood cells (RBCs). These substances are important because they contain specific sequences of
amino acid and
carbohydrate which are
antigenic. As well as being on the surface of RBCs, some of these antigens are also present on the cells of other tissues. A complete
blood type describes the 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; usually only the
ABO blood group system and the presence or absence of the
Rhesus D antigen (also known as the Rhesus factor) are determined and used to describe the blood type. Over 400 different blood group antigens have been found, many of these being very rare. If an individual is exposed to a blood group antigen that is not recognised as self, the individual can become sensitized to that antigen; the
immune system makes specific
antibodies which binds specifically to a particular blood group antigen and an immunological memory against that particular antigen is formed. 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. Knowledge of an individual's blood type is important to identify appropriate
blood for
transfusion or tissue for
organ transplantation.
Several different RBC surface antigens stemming from one
allele (or very closely linked
genes) are collectively labeled as a
blood group system (or blood group). The two most important blood group systems were discovered during early experiments with blood transfusion, the
ABO group in
1901 and the
Rhesus group in
1937 . These two blood groups are reflected in the common nomenclature
A positive,
O negative, etc. with letters referring to the ABO group and positive/negative to the presence/absence of the RhD antigen of the Rhesus group. Development of the
Coombs test in
1945 and the advent of
transfusion medicine led to discovery of more blood groups. The
Coombs test is important in the screening of blood for blood group antibodies in the preparation of blood for
transfusion.
Blood types are
inherited and represent contributions from both parents. Some blood types are rare, and are primarily found in certain ethnic groups. Some blood types are associated with inheritance of other diseases, such as the
Kell antigen is associated with
McLeod syndrome. Some blood types help protect from disease, such as the
Duffy antigen giving partial resistance to
malaria. Very rarely, a person's blood type changes through addition or suppression of an antigen in
infection or
malignancy.
Serious
reactions can occur if a person is exposed to blood of a different blood type. In blood transfusion, mismatches 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.
Often,
pregnant women carry a
fetus with a different blood type to herself, and sometimes the mother forms antibodies against the red blood cells of the fetus, leading to
low fetal blood counts, a condition known as
hemolytic disease of the newborn.
ABO and Rhesus: the two main blood group systems
The
ABO system is the most important blood type system in human blood transfusion. The associated anti-A
antibodies and anti-B antibodies are usually powerful
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
Rhesus system is the second most important blood type system in human blood transfusion. The most important Rhesus antigen is the
RhD antigen because it is the most immunogenic of the five main rhesus antigens; however, anti-RhD antibodies are not usually produced by sensitization against environmental substances. It is common for RhD negative individuals not to have any anti-RhD IgG or IgM antibodies; nevertheless, RhD negative individuals can produce powerful
IgG antibodies when they are transfused with RhD positive
RBCs.
Distribution of ABO and Rh Blood types (averages for each population)| Population | O+ | A+ | B+ | AB+ | Oâˆ' | Aâˆ' | Bâˆ' | ABâˆ' |
|---|
| USA | 38% | 34% | 9% | 3% | 7% | 6% | 2% | 1% |
|---|
| UK | 37% | 35% | 8% | 3% | 7% | 7% | 2% | 1% |
|---|
| Australia | 40% | 31% | 8% | 2% | 9% | 7% | 2% | 1% |
|---|
| Finland | 27% | 38% | 15% | 7% | 4% | 6% | 2% | 1% |
|---|
| Sweden | 32% | 37% | 10% | 5% | 6% | 7% | 2% | 1% |
|---|
Other human blood group systems
The
International Society of Blood Transfusion currently recognizes 29 blood group systems
[From: http://www.iccbba.com/ (accessed June 2006)](including the ABO and Rh systems). 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), Le
a or Le
b positive (Lewis system), and so on for each blood group system. Many of the blood group systems were named after the patients in whom the corresponding antibodies were initially encountered.
Importance for transfusions
Transfusion medicine is a specialized branch of
hematology that is concerned with the study of blood group antigens and blood group antibodies, 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 to medicines. In the USA blood products are tightly regulated by the
Food and Drug Administration.
Blood transfusions between
donor and recipient of incompatible blood types can cause severe acute immunological reactions,
hemolysis (RBC destruction),
renal failure,
shock, and sometimes death. Antibodies can be highly active and can attack RBCs and bind components of the
complement system to cause massive hemolysis of the transfused blood.
Hemolytic disease of the newborn
An
antenatal woman can make
IgG blood group antibodies, if her fetus has a blood group antigen that she does not. This can happen if some of the fetuses blood cells pass into the mother's blood circulation (ie a small fetomaternal
hemorrhage at the time of child birth) or sometimes after a therapeutic
blood transfusion. This can lead to
Rh disease or another forms of
hemolytic disease of the newborn (HDN) in her current baby or in subsequent pregnancies. Some blood groups can cause severe HDN, some can only cause mild HDN and others are not known to cause HDN.
Blood products
In order to provide maximum benefit from each blood donation and to extend shelf-life,
blood banks
fractionate whole blood into several products. The most common of these products are packed RBCs, plasma,
platelets,
cryoprecipitate, and
fresh frozen plasma (FFP). FFP is quick-frozen to retain labile
clotting factors
V and
VIII and usually administered to patients who have a potentially fatal clotting problem caused by a condition such as advanced
liver disease, overdose of
anticoagulant, or
disseminated intravascular coagulation (DIC).
Clotting factors synthesized by modern
recombinant methods are now in routine clinical use for
hemophilia, as the risks of infection transmission that occur with pooled blood products are avoided.
Cross matching blood
A patient should ideally receive their own blood or type-specific blood products to minimize the chance of a
transfusion reaction. If time allows, the risk will further be reduced by
cross-matching blood, in addition to blood typing both recipient and donor. 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. Blood bank technicians usually check for
agglutination with a
microscope, and if it occurs, that particular donor's blood cannot be transfused to that particular recipient. Blood transfusion is a potentially risky medical procedure and it is vital that all blood specimens are correctly identified, so in cross-matching labeling is standardized using a
barcode system known as
ISBT 128.
RBC compatibility
*
Blood group AB individuals have both A and B antigens on the surface of their RBCs, and their
blood serum does not contain any antibodies against either A or B antigen. Therefore, an individual with type AB blood can receive blood from any group (with AB being preferable), but can only donate blood to another group AB individual.
*
Blood group A individuals have the A antigen on the surface of their RBCs, and
blood serum containing
IgM antibodies against the B antigen. Therefore, a group A individual can only receive blood from individuals of groups A or O (with A being preferable), and can donate blood to individuals of groups A or AB.
*
Blood group B individuals have the B antigen on their surface of their RBCs, and
blood serum containing
IgM antibodies against the A antigen. Therefore, a group B individual can only receive blood from individuals of groups B or O (with B being preferable), and can donate blood to individuals of groups B or AB.
*
Blood group O individuals do not have either A or B antigens on the surface of their RBCs, but their
blood serum contains
IgM antibodies against both A and B antigens. Therefore, a group O individual can only receive blood from a group O individual, but they can donate blood to individuals of any ABO blood group (ie A, B, O or AB).
|
Donors of blood type O can give to A, B & AB; donors of types A & B can give to AB. |
RBC compatibility table| Recipient blood type | Donor must be | | AB+ | Any blood type |
| AB- | O- | A- | B- | AB- |
| A+ | O- | O+ | A- | A+ |
| A- | O- | A- | | |
| B+ | O- | O+ | B- | B+ |
| B- | O- | B- | | |
| O+ | O- | O+ | | |
| O- | O- | | | |
An RhD negative patient (who has not been sensitized to RhD positive RBCs and who does not have any anti-D antibodies) can receive RhD positive blood cells, but there is a high probability that this would sensitize the patient to the RhD antigen, and a female patient would risk
HDN. Therefore RhD positive blood is never given to RhD negative women of childbearing age, and is only given to other RhD negative patients in extreme circumstances, such as a major bleed when RhD negative red cells are running short. If a RhD negative patient has developed anti-D antibodies, a second exposure to RhD positive blood would lead to a potentially dangerous transfusion reaction. Occasionally, for transfusion of males or women above child-bearing age, RhD positive blood is given to a RhD negative individual (who do not have atypical red cell antibodies) when it is necessary to conserve RhD negative blood stocks in the blood bank for use in people where sensitisation to RhD antigens could cause serious problems. The converse is not true: RhD positive patients do not react to RhD negative blood.
Plasma compatibility
|
Plasma from type AB can be given to A, B & O; plasma from types A & B can be given to O. |
Donor-recipient compatibility for
blood plasma is the reverse from that of RBCs. Plasma extracted from type AB blood can be transfused to individuals of any blood group, but type O plasma can only be used by type O recipients.
Rhesus D antibodies are not usually naturally occurring, so generally both RhD negative and RhD positive blood do not contain anti-RhD antibodies, and so generally RhD negative or RhD positive donor blood plasma can be transfused into both RhD negative and RhD positive recipients. Hence, there is no need to specify RhD positive or RhD negative in the table below. If anti-RhD antibodies have developed in a donor these would be detected by antibody screening in the blood bank. Donor blood containing anti-RhD antibodies would not be suitable for transfusion into a RhD positive patient, but anyone with any strong atypical blood group antibodies would not be accepted as a blood donor.
Plasma compatibility table| Recipient blood type | Donor must be | | AB | AB |
| A | A or AB |
| B | B or AB |
| O | Any blood type |
Universal donors and universal recipients
Individuals with blood type O negative are often called
universal donors and individuals with type AB positive blood are called
universal recipients, but the terms
universal donor and
universal recipient are not very useful, because they only consider the reaction of the patient's antibodies to received red blood cells, and not the antibodies present in the transfused blood. These terms may be generally true for transfusions of packed red cells, where as much of the plasma as possible has been removed. Thus, although a transfusion of O negative blood to a patient of blood group A or B is unlikely to produce an immune reaction due to the recipient's antibodies, the transfused blood may itself contain antibodies to the patient's A and B antigens; this can cause an adverse reaction, although the risk is far less than that of an O negative patient receiving types A or B. For this reason an exact ABO-type match is preferable where circumstances allow. Additionally, the other red blood cell surface antigens that belong to blood groups outside of the ABO blood group system might cause an adverse reaction if they can bind the corresponding antibodies.
With respect to transfusions of
plasma this situation is reversed. Type O plasma can only be given to O recipients, while AB plasma (which does not contain anti-A or anti-B antibodies) can be given to patients of any ABO blood group.
Transfusion are further complicated because
platelets and
WBCs have their own systems of surface antigens and sensitization to platelet or WBC antigens can occur as a complication of transfusion.
*
Blood group test online*Blood types have applications in
forensic science and in
paternity testing; however, they are being replaced by
DNA studies which provide greater certitude.
*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. Correspondingly, blood services in these areas may look to encourage westerners to donate blood.
*Some blood types may offer protection from certain disorders and illnesses. For example,
Duffy blood group is related to immunity against some kinds of
malaria, and is more common in ethnic groups from areas with a high incidence of malaria, probably as a result of
natural selection.
*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. This belief has carried over to 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.
*Some front-line military personnel choose to be
tattooed with their blood type in case they should need an emergency blood transfusion.
*Rare blood types can cause supply problems for
blood banks and hospitals. For example, U-negative and Duffy-negative are two blood groups that occur only within people of African origin, and even then they are rare traits. The rarity of these factors can result in a shortage of U-negative and Duffy-negative blood for patients of African ethnicity.
*The ABO antigen is also expressed on the
von Willebrand factor (vWF)
glycoprotein, which participates in
hemostasis (control of bleeding). In fact, having type O blood predisposes very slightly to bleeding, as vWF is degraded more rapidly.
*In
Nazi Germany research was done to associate B-type blood type with inferior personal characteristics. B-type blood was relatively common among German
Jewish populations. This research has since been discredited.
*The
blood type diet is a system whereby people modify their food intake and lifestyle according to their ABO blood group and secretor status for health.
*Mollison PL, Engelfriet CP and Contreras M. Blood Transfusion in Clinical Medicine. 1997. 10th edition. Blackwell Science, Oxford, UK.
* (ABO) and (Rh/D)
*
ABO World Japanese Blood Typing theory (web site in Japanese)
*
All about blood groups bloodbook.com
*
Alternative Definition of blood group*
Asian Blood ABO allele distribution among Asians
*
Australian blood statistics - Aust. Red Cross Blood Service
*
Blood type diet - dadamo.com
*
Definition of Blood Group - Merriam-Webster
*
History of ABO blood types Blood group serology1939).
*
Racial & Ethnic Distribution of ABO Blood Types - bloodbook.com
*
Racial and Ethnic distribution of Rh blood types - madsci.org
*
Rare blood groups - LifeShare blood center
