Blood Grouping

What are the different blood groups?
The differences in human blood are due to the presence or absence of certain protein molecules called antigens and antibodies. The antigens are located on the surface of the red blood cells and the antibodies are in the blood plasma. Individuals have different types and combinations of these molecules. The blood group you belong to depends on what you have inherited from your parents.

There are more than 20 genetically determined blood group systems known today, but the AB0 and Rh systems are the most important ones used for blood transfusions. Not all blood groups are compatible with each other. Mixing incompatible blood groups leads to blood clumping or agglutination, which is dangerous for individuals.

Nobel Laureate Karl Landsteiner was involved in the discovery of both the AB0 and Rh blood groups.

AB0 blood grouping system

According to the AB0 blood typing system there are four different kinds of blood types:
A, B, AB or O.

Group O
If you belong to the blood group O, you have neither A or B antigens on the surface of your red blood cells but you have both A and B antibodies in your blood plasma.

O Negative blood can be given to anyone in an emergency and O Negative donors are known as the “Universal donors”.

Rh factor blood grouping system
Many people also have a so called Rh factor on the red blood cell's surface. This is also an antigen and those who have it are called Rh+. Those who haven't are called Rh-. A person with Rh- blood does not have Rh antibodies naturally in the blood plasma (as one can have A or B antibodies, for instance). But a person with Rh- blood can develop Rh antibodies in the blood plasma if he or she receives blood from a person with Rh+ blood, whose Rh antigens can trigger the production of Rh antibodies. A person with Rh+ blood can receive blood from a person with Rh- blood without any problems.

Distribution of blood groups among blood donors in South Africa:
O Positive-39%
O Negative- 6%

Group AB
If you belong to the blood group AB, you have both A and B antigens on the surface of your red blood cells and no A or B antibodies at all in your blood plasma.

People with AB positive blood types are the “universal recipients” as they can receive blood from all blood groups.

Rh factor blood grouping system
Many people also have a so called Rh factor on the red blood cell's surface. This is also an antigen and those who have it are called Rh+. Those who haven't are called Rh-. A person with Rh- blood does not have Rh antibodies naturally in the blood plasma (as one can have A or B antibodies, for instance). But a person with Rh- blood can develop Rh antibodies in the blood plasma if he or she receives blood from a person with Rh+ blood, whose Rh antigens can trigger the production of Rh antibodies. A person with Rh+ blood can receive blood from a person with Rh- blood without any problems.

Distribution of blood groups among blood donors in South Africa:
AB Positive- 3%
AB Negative- 1%

Group A
If you belong to Group A blood, you have A antigens on the surface of your red blood cells and B antibodies in your blood plasma.

Rh factor blood grouping system
Many people also have a so called Rh factor on the red blood cell's surface. This is also an antigen and those who have it are called Rh+. Those who haven't are called Rh-. A person with Rh- blood does not have Rh antibodies naturally in the blood plasma (as one can have A or B antibodies, for instance). But a person with Rh- blood can develop Rh antibodies in the blood plasma if he or she receives blood from a person with Rh+ blood, whose Rh antigens can trigger the production of Rh antibodies. A person with Rh+ blood can receive blood from a person with Rh- blood without any problems.

Distribution of blood groups among blood donors in South Africa:
A Positive- 32%
A Negative- 5%

Group B

If you belong to the Blood Group B, you have B antigens on the surface of your red blood cells and A antibodies in your blood plasma.

Rh factor blood grouping system
Many people also have a so called Rh factor on the red blood cell's surface. This is also an antigen and those who have it are called Rh+. Those who haven't are called Rh-. A person with Rh- blood does not have Rh antibodies naturally in the blood plasma (as one can have A or B antibodies, for instance). But a person with Rh- blood can develop Rh antibodies in the blood plasma if he or she receives blood from a person with Rh+ blood, whose Rh antigens can trigger the production of Rh antibodies. A person with Rh+ blood can receive blood from a person with Rh- blood without any problems.

Distribution of blood groups among blood donors in South Africa:
B Positive- 12 %
B Negative- 2%