ABO blood group system | Definition, Blood Type, & ABO Antigens | caztuning.info
ABO blood group antigens present on red blood cells and IgM antibodies present in the serum. The ABO blood group system is used to denote the presence of one , both, or neither of the A They were also the first to explain the genetic inheritance of the blood groups.) Jan Janský, who invented type I, II, III, IV system. This chapter will describe the types of red blood cell antigen and explain why they antibodies to cover fetal red blood cell antigens and removing them from the. What is blood typing? If you are blood group A, you will have antibodies to antigen B. If you are blood group B, you will have antibodies to antigen A. If you are.
People with weak alleles of A can sometimes express anti-A antibodies, though these are usually not clinically significant as they do not stably interact with the antigen at body temperature. Distribution and evolutionary history[ edit ] Main article: Blood type distribution by country The distribution of the blood groups A, B, O and AB varies across the world according to the population.
There are also variations in blood type distribution within human subpopulations. In the UK, the distribution of blood type frequencies through the population still shows some correlation to the distribution of placenames and to the successive invasions and migrations including NorsemenDanesSaxonsCeltsand Normans who contributed the morphemes to the placenames and the genes to the population.
A premature stop codon results from this frame-shift mutation. This variant is found worldwide, and likely predates human migration from Africa.
The O01 allele is considered to predate the O02 allele. The A allele encodes a glycosyltransferase that produces the A antigen N-acetylgalactosamine is its immunodominant sugarand the B allele encodes a glycosyltransferase that creates the B antigen D-galactose is its immunodominant sugar. See the structures of the A, B, and O antigens in Stryer's Biochemistry The O allele encodes an enzyme with no function, and therefore neither A or B antigen is produced, leaving the underlying precursor the H antigen unchanged.
These antigens are incorporated into one of four types of oligosaccharide chain, type 2 being the most common in the antigen-carrying molecules in RBC membranes.
Some of the other enzymes involved in the earlier stages of ABO antigen synthesis are also involved in producing antigens of the Hh blood group and the Lewis blood group. Expression Although the ABO blood group antigens are regarded as RBC antigens, they are actually expressed on a wide variety of human tissues and are present on most epithelial and endothelial cells.
Other blood cells, such as T cells, B cells, and platelets, have ABO blood group antigens that have been adsorbed from the plasma.
Blood Type - Antigens And Antibodies
In individuals who are "secretors", a soluble form of the ABO blood group antigens is found in saliva and in all bodily fluids except for the cerebrospinal fluid. A number of illnesses may alter a person's ABO phenotype. Patients can "acquire" the B antigen during a necrotizing infection during which bacteria release an enzyme into the circulation that converts the A1 antigen into a B-like antigen 3.
During this time, patients should not receive blood products that contain the B antigen because their sera will still contain anti-B. Once the underlying infection is treated, the patients' blood groups return to normal.
Illness can also cause patients to "lose" ABO blood group antigens. In addition, ABO blood group antigens can be altered by hematological cancers that can modify the sugar chains that bear the ABO blood group antigens, lending to the use of the A and B antigens as tumor markers for acute leukemia, myeloproliferative disorders, and myelodysplasia.
Individuals who lack the A and B antigens are healthy, suggesting that any function the antigens have is not important, at least not in modern times.
Diseases associated with ABO blood group antigens No diseases are known to result from the lack of expression of ABO blood group antigens, but the susceptibility to a number of diseases has been linked with a person's ABO phenotype.
Such correlations remain controversial and include the observation that gastric cancer appears to be more common in group A individuals 4whereas gastric and duodenal ulcers occur more often in group O individuals 5. It is well established that low levels of FVIII and vWF are a cause of excess bleeding, and therefore it may also be the case that increased levels make clotting more likely, increasing the risk of both arterial ischemic heart disease and venous thromboembolic disease problems.
Indeed, non-group O individuals have been shown to be at an increased risk of both arterial and venous disease 6. Transfusion reactions The routine practice of blood typing and cross matching blood products should prevent adverse transfusion reactions caused by ABO antibodies. However, clerical error can result in "the wrong blood" being transfused into a patient, an error which can result in the death of the patient 7, 8.
If a recipient who has blood group O is transfused with non-group O RBCs, the naturally occurring anti-A and anti-B in the recipient's serum binds to their corresponding antigens on the transfused RBCs.
Blood group - The importance of antigens and antibodies | caztuning.info
These antibodies fix complement and cause rapid intravascular hemolysis, triggering an acute hemolytic transfusion reaction that can cause disseminated intravascular coagulation, shock, acute renal failure, and death. Anti-A1 is a less significant cause of transfusion reactions and does not appear to fix complement. Hemolytic disease of the newborn Most cases of hemolytic disease of the newborn HDN that arise from an ABO incompatibility require no treatment.
Bring fact-checked results to the top of your browser search. The importance of antigens and antibodies The red cells of an individual contain antigens on their surfaces that correspond to their blood group and antibodies in the serum that identify and combine with the antigen sites on the surfaces of red cells of another type. The reaction between red cells and corresponding antibodies usually results in clumping— agglutination —of the red cells; therefore, antigens on the surfaces of these red cells are often referred to as agglutinogens.
Antibodies are part of the circulating plasma proteins known as immunoglobulins, which are classified by molecular size and weight and by several other biochemical properties. Most blood group antibodies are found either on immunoglobulin G IgG or immunoglobulin M IgM molecules, but occasionally the immunoglobulin A IgA class may exhibit blood group specificity. Naturally occurring antibodies are the result of immunization by substances in nature that have structures similar to human blood groups.
These antibodies are present in an individual despite the fact that there has been no previous exposure to the corresponding red cell antigens—for example, anti-A in the plasma of people of blood group B and anti-B in the plasma of people of blood group A. Immune antibodies are evoked by exposure to the corresponding red cell antigen. The combination of pregnancy and transfusion is a particularly potent stimulus.
- ABO blood group system
Individual blood group antigens vary in their antigenic potential; for example, some of the antigens belonging to the Rh and ABO systems are strongly immunogenic i. The blood group antigens are not restricted solely to red cells or even to hematopoietic tissues.
The antigens of the ABO system are widely distributed throughout the tissues and have been unequivocally identified on platelets and white cells both lymphocytes and polymorphonuclear leukocytes and in skin, the epithelial lining cells of the gastrointestinal tractthe kidney, the urinary tract, and the lining of the blood vessels.
Evidence for the presence of the antigens of other blood group systems on cells other than red cells is less well substantiated.
Among the red cell antigens, only those of the ABO system are regarded as tissue antigens and therefore need to be considered in organ transplantation.