Blood group systems are necessary to identify suitable products for transfusion.
Their clinical importance also relates to the production of alloantibodies that destroy transfused blood cells or that cross the placenta and give rise to haemolytic disease in the fetus and newborn.
This is dependent upon:
- the frequency with which alloantigens and alloantibodies occur, which may be different among ethnic groups
- the functional characteristics of alloantibodies: thermal range, immunoglobulin class, titre, avidity and ability to fix complement, and
- the presence of autoantibodies that are relevant to the diagnosis and management of autoimmune blood disorders and that may interfere with compatibility testing.