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Blood groups are explicated in this Sqadia video. One of the classes (such as those designated A, B, AB, or O) into which individuals or their blood can be separated on the basis of the presence or absence of specific antigens in the blood called also blood type. When blood transfusions were first attempted, immediate or delayed agglutination and haemolysis led to death. Karl Landsteiner discovered that the bloods of different people have different antigenic and immune properties. Antibodies in the plasma of one blood will react with antigens on the surfaces of the red cells of another blood type. Austrian scientist Karl Landsteiner, who identified the O, A, and B blood types in 1900. If an agglutinogen is present on red blood cell membrane, the corresponding agglutinin must be absent in the plasma, if an agglutinogen is absent on red blood cell membrane, then corresponding agglutinin must be present in the plasma.
Blood Group Systems
Two particular types of antigens are much more likely than the others to cause blood transfusion reactions: A-O-B system and Rh system. ABO blood group system, the classification of human blood based on the inherited properties of red blood cells (erythrocytes) as determined by the presence or absence of the antigens A and B, which are carried on the surface of the red cells. Persons may thus have type A, type B, type O, or type AB blood.
Matching and Reactions
Testing before a blood transfusion to determine if the donor's blood is compatible with the blood of an intended recipient. Testing for the presence of antibodies against the antigens in a sample of donor blood or other tissue. Cross-matching used to determine compatibility between a donor and recipient in organ transplantation. When the membranes of the agglutinated cells are destroyed by physical distortion of the cells and attack by phagocytic white blood cells releasing haemoglobin into the plasma, which is called “haemolysis” of RBC’s.
The Rh system (Rh meaning Rhesus) is the second most significant blood-group system in human-blood transfusion with currently 50 antigens. The most significant Rh antigen is the D antigen, because it is the most likely to provoke an immune system response of the five main Rh antigens. It is common for D-negative individuals not to have any anti-D IgG or IgM antibodies, because anti-D antibodies are not usually produced by sensitization against environmental substances. However, D-negative individuals can produce IgG anti-D antibodies following a sensitizing event: possibly a fetomaternal transfusion of blood from a fetus in pregnancy or occasionally a blood transfusion with D positive RBCs. Rh disease can develop in these cases. Rh negative blood types are much less common in Asian populations (0.3%) than they are in European populations (15%). The presence or absence of the Rh(D) antigen is signified by the + or − sign, so that, for example, the A− group is ABO type A and does not have the Rh (D) antigen.
Other Groups of Blood
Thirty-three blood-group systems have been identified by the International Society for Blood Transfusion in addition to the common ABO and Rh systems. Thus, in addition to the ABO antigens and Rh antigens, many other antigens are expressed on the RBC surface membrane. For example, an individual can be AB, D 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. Replace the neonate’s blood with Rh-negative blood. The anti-D antibody administered to Rh-ve women who deliver Rh-positive babies to prevent sensitization of the mothers to the D antigen.