Blood types

Blood types: who can give blood to whom? What determines which blood types are accepted or rejected by individual in blood donation?

Who can give blood to whom? What determines which blood types are accepted or rejected by individuals in blood donation involves an understanding of what blood types are and how the body reacts to donated blood and why. Terms such as antigens, antibodies, play heavily in the description of the blood donation process.

There are four blood types; “A”, “B”, “AB”, and “O”. These types are the names that identify the protein antigen or “coat” that surrounds the red blood cells. The antigen coat not only identifies the blood type, but also identifies the antibodies that are produced by the individual. An individual’s blood types antigens determine the blood type antibodies that attack foreign blood.

Type A blood is so named because the individual with this type blood has the “A” antigen coat on his or her red blood cells. This means that this individual’s body produces the antibody for the “B” antigen. What this means is that if a person that has type “B” blood attempts to donate blood to a type A person, the antibodies of that person’s blood will react violently. The individual reaction that of the type A receiver of this unacceptable type B blood donation is often deadly. This is because the type A antibodies attack the B coated red blood cells in a reaction that not only destroys the B cells, but also breaks down the individual circulatory system. The pattern of antibody-antigen for the other blood types is as follows:

Type B blood carries the “B” antigen and the A antibodies.

Type AB blood carries both A and B antigen coats, but no antibodies.

While Type O blood has no antigen coat, and both A and B antibodies.

This breakdown was often described as “blood poisoning” when the technique of blood transfusion was first used before it was fully understood. Though practiced in the 18th century with varying success due to the lack of understanding, blood donation transfusions were known to be a risky proposition. The discovery of the relationships of types, antigens, and antibodies made blood donation a science. The ability to donate or receive blood is dependent of the relationship of antibodies and antigens.

Type O blood has no antigen coat and can be given to all blood types. This is because it has no antigen to trigger an antibody response. Type O blood is known as the universal donor. At the same time because it has both A and B antibodies, individuals with Type O blood can only receive blood from other Type O donors.

Type A blood can be donated to individuals with Type A and Type AB blood. This is because Type A blood will not trigger an antibody reaction in either of these types. Type A can receive blood from Type A or Type O.

Type B blood can be donated to individuals with Type B and Type AB blood. This is because Type B blood will not trigger an antibody reaction in individuals these individuals. Type B individuals can receive blood form Type B and Type O.

Type AB blood can be donated to individuals with Type AB blood only. Due to the dual antigen coat of Type AB blood, it causes an antibody response in all other blood types. Type AB blood on the other hand is known as the “universal acceptor” because individuals with this blood type have no antibodies that react to the presence of either the A or B blood antigen coat.

In review; A person with Type A blood carries the “A” antigen and the B antibodies; Individuals with Type B blood carry the “B” antigen and the A antibodies. Type AB blood carries both A and B antigen coats, but no antibodies, therefore are known as “universal acceptors”. While individuals with Type O blood have no antigen coats, therefore are “universal donors”, and have both A and B antibodies making them only able to accept their own type.

Type Antigen(s)Antibody Receive Donate to

A A B A and O A and AB

B B A B and O B and AB

AB A and B None AB, A, B, O AB

O None A and B O A, B, AB, &O

Written by Charles Grimmett