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A blood type is a classification of blood, based on the presence and absence of antibodies and 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. 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 can stem from one allele and collectively form a blood group system.
Hemolytic disease of the newborn, also known as hemolytic disease of the fetus and newborn, HDN, HDFN, or erythroblastosis fetalis, is an alloimmune condition that develops in a fetus at or around birth, when the IgG molecules produced by the mother pass through the placenta. Among these antibodies are some which attack antigens on the red blood cells in the fetal circulation, breaking down and destroying the cells. The fetus can develop reticulocytosis and anemia. The intensity of this fetal disease ranges from mild to very severe, and fetal death from heart failure can occur. When the disease is moderate or severe, many erythroblasts are present in the fetal blood, earning these forms of the disease the name erythroblastosis fetalis.
The direct and indirect Coombs tests, also known as antiglobulin test (AGT), are blood tests used in immunohematology. The direct Coombs test detects antibodies that are stuck to the surface of the red blood cells. Since these antibodies sometimes destroy red blood cells they can cause anemia; this test can help clarify the condition. The indirect Coombs test detects antibodies that are floating freely in the blood. These antibodies could act against certain red blood cells; the test can be carried out to diagnose reactions to a blood transfusion.
Autoimmune hemolytic anemia (AIHA) is an autoimmune disorder which occurs when antibodies directed against the person's own red blood cells (RBCs) cause them to burst (lyse), leading to an insufficient number of oxygen-carrying red blood cells in circulation (anemia). The lifetime of the RBCs is reduced from the normal 100–120 days to just a few days in serious cases. The intracellular components of the RBCs are released into the circulating blood and into tissues, leading to some of the characteristic symptoms of this condition. The antibodies are usually directed against high-incidence antigens, therefore they also commonly act on allogenic RBCs. AIHA is a relatively rare condition, with an incidence of 5–10 cases per 1 million persons per year in the warm-antibody type and 0.45 to 1.9 cases per 1 million persons per year in the cold-antibody type. Autoimmune hemolysis might be a precursor of later onset systemic lupus erythematosus.
In ABO hemolytic disease of the newborn maternal IgG antibodies with specificity for the ABO blood group system pass through the placenta to the fetal circulation where they can cause hemolysis of fetal red blood cells which can lead to fetal anemia and HDN. In contrast to Rh disease, about half of the cases of ABO HDN occur in a firstborn baby and ABO HDN does not become more severe after further pregnancies.
Hemolytic disease of the newborn (anti-Rhc) can range from a mild to a severe disease. It is the third most common cause of severe HDN. Rh disease is the most common and hemolytic disease of the newborn (anti-Kell) is the second most common cause of severe HDN. It occurs more commonly in women who are Rh D negative.
The term human blood group systems is defined by the International Society of Blood Transfusion (ISBT) as systems in the human species where cell-surface antigens—in particular, those on blood cells—are "controlled at a single gene locus or by two or more very closely linked homologous genes with little or no observable recombination between them", and include the common ABO and Rh (Rhesus) antigen systems, as well as many others; 44 human systems are identified as of 31 December 2022.
The Kidd antigen system are proteins found in the Kidd's blood group, which act as antigens, i.e., they have the ability to produce antibodies under certain circumstances. The Jk antigen is found on a protein responsible for urea transport in the red blood cells and the kidney. They are important in transfusion medicine. People with two Jk(a) antigens, for instance, may form antibodies against donated blood containing two Jk(b) antigens. This can lead to hemolytic anemia, in which the body destroys the transfused blood, leading to low red blood cell counts. Another disease associated with the Jk antigen is hemolytic disease of the newborn, in which a pregnant woman's body creates antibodies against the blood of her fetus, leading to destruction of the fetal blood cells. Hemolytic disease of the newborn associated with Jk antibodies is typically mild, though fatal cases have been reported.
The Rh blood group system is a human blood group system. It contains proteins on the surface of red blood cells. After the ABO blood group system, it is the most likely to be involved in transfusion reactions. The Rh blood group system consisted of 49 defined blood group antigens in 2005. As of 2023, there are over 50 antigens among which the five antigens D, C, c, E, and e are the most important. There is no d antigen. Rh(D) status of an individual is normally described with a positive (+) or negative (−) suffix after the ABO type. The terms Rh factor, Rh positive, and Rh negative refer to the Rh(D) antigen only. Antibodies to Rh antigens can be involved in hemolytic transfusion reactions and antibodies to the Rh(D) and Rh antigens confer significant risk of hemolytic disease of the newborn.
The MNS antigen system is a human blood group system based upon two genes on chromosome 4. There are currently 50 antigens in the system, but the five most important are called M, N, S, s, and U.
P1PK is a human blood group system based upon the A4GALT gene on chromosome 22. The P antigen was first described by Karl Landsteiner and Philip Levine in 1927. The P1PK blood group system consists of three glycosphingolipid antigens: Pk, P1 and NOR. In addition to glycosphingolipids, terminal Galα1→4Galβ structures are present on complex-type N-glycans. The GLOB antigen is now the member of the separate GLOB (globoside) blood group system.
Hemolytic disease of the newborn (anti-RhE) is caused by the anti-RhE antibody of the Rh blood group system. The anti-RhE antibody can be naturally occurring, or arise following immune sensitization after a blood transfusion or pregnancy.
In addition to the defined human blood group systems, there are erythrocyte antigens which do not meet the definition of a blood group system. Most of these are either nearly universal in human blood or extremely rare and are rarely significant in a clinical setting. Reagents to test for these antigens are difficult to find and many cannot be purchased commercially.
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The Vel blood group is a human blood group that has been implicated in hemolytic transfusion reactions. The blood group consists of a single antigen, the high-frequency Vel antigen, which is expressed on the surface of red blood cells. Individuals are typed as Vel-positive or Vel-negative depending on the presence of this antigen. The expression of the antigen in Vel-positive individuals is highly variable and can range from strong to weak. Individuals with the rare Vel-negative blood type develop anti-Vel antibodies when exposed to Vel-positive blood, which can cause transfusion reactions on subsequent exposures.
The Junior blood group system is a human blood group defined by the presence or absence of the Jr(a) antigen, a high-frequency antigen that is found on the red blood cells of most individuals. People with the rare Jr(a) negative blood type can develop anti-Jr(a) antibodies, which may cause transfusion reactions and hemolytic disease of the newborn on subsequent exposures. Jr(a) negative blood is most common in people of Japanese heritage.
Blood compatibility testing is conducted in a medical laboratory to identify potential incompatibilities between blood group systems in blood transfusion. It is also used to diagnose and prevent some complications of pregnancy that can occur when the baby has a different blood group from the mother. Blood compatibility testing includes blood typing, which detects the antigens on red blood cells that determine a person's blood type; testing for unexpected antibodies against blood group antigens ; and, in the case of blood transfusions, mixing the recipient's plasma with the donor's red blood cells to detect incompatibilities (crossmatching). Routine blood typing involves determining the ABO and RhD type, and involves both identification of ABO antigens on red blood cells and identification of ABO antibodies in the plasma. Other blood group antigens may be tested for in specific clinical situations.
The Lan blood group system is a human blood group defined by the presence or absence of the Lan antigen on a person's red blood cells. More than 99.9% of people are positive for the Lan antigen. Individuals with the rare Lan-negative blood type, which is a recessive trait, can produce an anti-Lan antibody when exposed to Lan-positive blood. Anti-Lan antibodies may cause transfusion reactions on subsequent exposures to Lan-positive blood, and have also been implicated in mild cases of hemolytic disease of the newborn. However, the clinical significance of the antibody is variable. The antigen was first described in 1961, and Lan was officially designated a blood group in 2012.
The Sid blood group system is a human blood group defined by the presence or absence of the Sd(a) antigen on a person's red blood cells. About 96% of people are positive for the Sd(a) antigen, which is inherited as a dominant trait. Among Sd(a) positive individuals, the expression of the antigen ranges from extremely weak to extremely strong. Very strong expression of the antigen is referred to as a Sd(a++) phenotype. In addition to being expressed on red blood cells, Sd(a) is secreted in bodily fluids such as saliva and breast milk, and is found in the highest concentrations in urine. Urine testing is considered the most reliable method for determining a person's Sid blood type.
The Augustine blood group system is a human blood group system. It includes four red blood cell surface glycoprotein antigens which are encoded by alleles of the gene SLC29A1.
References
- 1 2 3 4 5 Karamatic Crew, V.; Tilley, L.A.; Satchwell, T.J.; AlSubhi, S.A.; Jones, B.; Spring, F.A.; et al. (2022). "Missense mutations in PIEZO1, encoding the Piezo1 mechanosensor protein, define the Er red blood cell antigens". Blood . 141 (2): 135–146. doi: 10.1182/blood.2022016504 . PMC 10644042 . PMID 36122374.
- 1 2 3 The Blood Group Antigen FactsBook, Elsevier, 2012, doi:10.1016/B978-0-12-415849-8.00038-7, ISBN 978-0-12-415849-8 , retrieved 2021-01-28
- ↑ Daniels, G. L.; Fletcher, A.; Garratty, G.; Henry, S.; Jørgensen, J.; Judd, W. J.; Levene, C.; Lomas-Francis, C.; Moulds, J. J.; Moulds, J. M.; Moulds, M. (November 2004). "Blood group terminology 2004: from the International Society of Blood Transfusion committee on terminology for red cell surface antigens". Vox Sanguinis. 87 (4): 304–316. doi:10.1111/j.1423-0410.2004.00564.x. hdl: 2027.42/73460 . ISSN 0042-9007. PMID 15585029. S2CID 1430414.
- ↑ Modern blood banking & transfusion practices. Harmening, Denise. (6th ed.). Philadelphia: F.A. Davis. 2012. ISBN 978-0-8036-2682-9. OCLC 762374313.
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