12.21: Blood Transfusion and Agglutination
Blood transfusion is a therapeutic measure to restore the blood volume after extensive blood loss due to an accident or a medical procedure. Blood transfusion involves drawing a certain amount of blood from a suitable donor and infusing it into the recipient.
The history of blood transfusion dates back to the 17th century, when early attempts were made in animals. In 1818 James Blundell, a British doctor, performed the first successful human blood transfusion. Later in 1900, Karl Landsteiner discovered A, B, and O blood types and paved the way for scientific blood transfusion techniques.
While whole blood is usually used during the transfusion event, however, based on the requirement, different blood components can also be used separately. For example, platelet fraction of donor blood is used to treat excessive bleeding caused by platelet deficiency. The immunoglobulins in the plasma are transfused to protect patients against viral infections.
Before the blood transfusion, several checks are run to ensure that the blood is safe from pathogens such as HBV, HCV, HIV, and HTLV-I/II and does not induce an immune reaction in the recipient’s body. For example, type-A blood cannot be given to an acceptor with type-B, or O, because the acceptors’ immune system would produce antibodies against incoming antigen-A, leading to a blood agglutination reaction in the host body.
Due to the lack of antigens, blood type-O does not elicit immune reactions with other blood types. Therefore, type-O blood can be given to patients with all other blood types. Conversely, a person with blood type-AB has no antibodies to either antigen A or B. Similarly, if an Rh-negative mother has a fetus with Rh-positive blood, she may produce antibodies against the fetus blood, resulting in the fatal hemolytic disease in the newborn.