jyoti bhatia
Last Activity: 8 Years ago
Subjects with blood group A carry the A antigen on their red blood cells and have antibodies to antigen B; subjects with blood group B have the B antigen and anti-A antibodies. Blood group AB carries both the A and B antigens and have no antibodies and folks with group O have no antigens but both antibodies.
Blood groups and transfusion: Circulating antibodies in a person’s blood will attack transfused RBCs from unmatching blood groups. These antibodies fix complement and cause rapid intravascular haemolysis, triggering an acute hemolytic transfusion reaction that can cause disseminated intravascular coagulation, shock, acute renal failure and death. As people with blood group AB have no antibodies, they can receive all blood groups without issues. People with blood group O can only receive RBCs of blood group O because they carry both antibodies. Blood group A can receive A and O and blood group B can receive B and O. hence, blood group O can be received by all other groups and is therefore universal donor.
Whether antibodies in donor’s blood with blood group O would start attacking cells in recipient with blood group A, B and AB? Yes, they will. Why then is O still the universal donor as they have both anti-A and anti-B antibodies?
Firstly, whole blood is not used for ‘routine’ blood transfusions. Instead, blood component therapy has replaced use of whole blood. For routine transfusions, only fraction containing packed red blood cells is transfused. Hence, in these cases, blood plasma containing antibodies is removed after centrifugation. Since O-type red blood cells contain no antigens and plasma with antibodies are not transfused, it can be donated to everyone, bar that rhesus factor matches.
Secondly, even if plasma is transfused, antibodies in donor’s plasma are a minor problem because of small amount of antibody present in donated plasma, which is further diluted on transfusion into recipient’s circulation.
