Blog

Ask the Expert- Why is Type O Known as the Universal Donor?

May 7, 2012 - There are several blood group systems present on the red blood cell membrane. The ABO blood group system is the most important in human transfusion. The ABO blood group was discovered in 1900 by Karl Landsteiner, who was awarded the Nobel Prize for Physiology or Medicine in 1930 for his work.

Within the ABO blood group system, an individual can be typed as A, B, AB or O depending on the nature of the protein (called antigen) present on his red blood cells, and the nature of the antibody present in his plasma.

Type A individuals have the A protein (antigen) on their red cells, and the antibody against type B in the plasma. Type B individuals have the B protein on their red cells, and the antibody against type A in the plasma. Type AB individuals have both A and B proteins on their red cells, and no antibody in the plasma. Type O individuals have neither A nor B protein on their red cells, and antibodies against type A and type B are present in their plasma.

In terms of blood transfusions, the rule is to give the same blood type or a blood type lacking the antigen against which the individual has the corresponding antibody in the plasma. Therefore, type A individuals can receive blood from type A or type O individuals; type B can receive blood from type B or type O individuals; type AB can receive blood from type AB, type A, type B or type O individuals; and type O can receive blood only from type O individuals.

Since any blood type in the ABO system can receive blood from type O individuals; type O is called the universal blood type. On the opposite end, type AB is known as the universal receiver because type AB individuals can receive blood from any blood type in the ABO system.