From the Guidelines
The ABO blood group system is identified by the presence or absence of A and B antigens on red blood cells and antibodies in the plasma, with four main blood types: A, B, AB, and O, which can be determined through blood typing tests using anti-A and anti-B antibodies. The ABO blood group system classifies blood based on the presence or absence of two antigens (A and B) on red blood cells and antibodies in the plasma. There are four main blood types: A (has A antigens), B (has B antigens), AB (has both A and B antigens), and O (has neither antigen). To identify blood types, laboratory technicians perform blood typing tests where they mix a blood sample with anti-A and anti-B antibodies and observe for agglutination (clumping) 1. Some key points to consider when identifying ABO blood groups include:
- If the blood clumps with anti-A antibodies, it contains A antigens (type A or AB)
- If it clumps with anti-B antibodies, it contains B antigens (type B or AB)
- If it clumps with both, it's type AB
- If it doesn't clump with either, it's type O This identification is crucial for blood transfusions because transfusing incompatible blood can cause severe immune reactions, as noted in the context of platelet transfusions where ABO-compatible products should be provided whenever possible 1. The ABO system works because people naturally develop antibodies against the antigens they don't have - type A people have anti-B antibodies, type B have anti-A antibodies, type O have both anti-A and anti-B antibodies, and type AB have neither antibody. This is why type O individuals are universal donors (their blood has no A or B antigens to trigger reactions) and type AB individuals are universal recipients (they have no antibodies against A or B antigens).
From the Research
ABO Blood Group System
The ABO blood group system consists of four antigens: A, B, O, and AB, which are oligosaccharide antigens widely expressed on the membranes of red cells and tissue cells, as well as in saliva and body fluids 2. These antigens are one of the most important issues in transfusion medicine, evaluating the adaptability of donor blood cells with bone marrow transplantations and the lifespan of hemocytes.
Identification of ABO Blood Groups
The ABO blood group antigens are recognized as blood groups and are the first human genetic markers known 3. The presence of these antigens and the realization of naturally occurring antibodies to those antigens lacking from the cells made sense of the erratic failure of blood transfusion hitherto and opened up the possibility of a safe treatment practice in life-threatening blood loss.
Clinical Significance of ABO Blood Groups
The ABO blood group is the most clinically significant blood group because of preformed immunoglobulin M (IgM) and IgG antibodies to ABO blood group antigens (isohemagglutinins) in everyone except group AB individuals 4. ABO incompatibility can cause hemolysis in hematopoietic and solid organ transplantation, hemolytic disease of the newborn, and intravenous immunoglobulin infusion.
Key Points to Consider
- The ABO blood group system consists of four antigens: A, B, O, and AB.
- ABO blood group antigens are widely expressed on the membranes of red cells and tissue cells, as well as in saliva and body fluids.
- ABO incompatibility can cause hemolysis in various clinical settings.
- ABO blood group screening may have a role in both thrombotic and hemorrhagic risk assessment 5.
- Immune complexes can be formed from anti-A and/or anti-B antibodies and ABO soluble antigen(s) present in donor and recipient plasma after ABO non-identical transfusions, affecting recipient red cell structural integrity, platelet function, and haemostasis 6.
ABO Blood Group and Transfusion Medicine
- The ABO blood group system is crucial in transfusion medicine to evaluate the adaptability of donor blood cells with bone marrow transplantations and the lifespan of hemocytes 2.
- ABO matching is important in platelet transfusion to prevent adverse effects such as hemolysis, increased red cell transfusion needs, and other complications 6.