Blood Groups


  • Like other cells in the body, red blood cells have complex molecules of carbohydrate polymers and proteins that give the cells their antigenicity.
  • The corollary to the above is the fact that antibodies exist that act against these antigens
  • In the presence of the particular antibodies, red cells agglutinate.
  • In contrast to clotting, agglutinated blood remains fluid, though the red cells clump together.
  • Though the large number of different antigens result in tens of different blood group systems, in practice there are only two, clinically important blood group systems. These are
  • The ABO system.
  • The Rhesus Factor System.