Blood Groups, Blood Typing and Blood Transfusions
Posted by admin on 9th February 2011
The discovery of blood groups
Experiments with blood transfusions, the transfer of blood or blood components into a person’s blood
stream, have been carried out for hundreds of years. Many patients have died and it was not until
1901, when the Austrian Karl Landsteiner discovered human blood groups, that blood transfusions
became safer.
Mixing blood from two individuals can lead to blood clumping or agglutination. The clumped red cells
can crack and cause toxic reactions. This can have fatal consequences. Karl Landsteiner discovered
that blood clumping was an immunological reaction which occurs when the receiver of a blood
transfusion has antibodies against the donor blood cells.
Karl Landsteiner’s work made it possible to determine blood groups and thus paved the way for blood
transfusions to be carried out safely. For this discovery he was awarded the Nobel Prize in Physiology
or Medicine in 1930.
What is blood made up of?
An adult human has about 4–6 liters of blood circulating in the body. Among other things, blood
transports oxygen to various parts of the body.
Blood consists of several types of cells floating around in a fluid called plasma.
The red blood cells contain hemoglobin, a protein that binds oxygen. Red blood cells transport
oxygen to, and remove carbon dioxide from, the body tissues.
The white blood cells fight infection.
The platelets help the blood to clot, if you get a wound for example.
The plasma contains salts and various kinds of proteins.
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 group system there are four different kinds of blood groups: A, B, AB or 0
(null).
Blood group A
If you belong to the blood group A, you have A antigens on the surface of
your red blood cells and B antibodies in your blood plasma.
Blood 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.
Blood 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.
Blood group 0
If you belong to the blood group 0 (null), 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.
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.
Blood group notation
According to above blood grouping systems, you can belong to either of following 8 blood groups:
A Rh+ B Rh+ AB Rh+ 0 Rh+
A Rh- B Rh- AB Rh- 0 Rh-
Can give blood Can receive
Blood Group Antigens Antibodies
to blood from
AB Rh+ A, B and Rh None AB Rh+ AB Rh+
AB Rh -
A Rh+
A Rh -
B Rh+
B Rh -
0 Rh+
0 Rh -
AB Rh - A and B None AB Rh - AB Rh -
(Can develop Rh AB Rh+ A Rh -
antibodies) B Rh -
0 Rh -
A Rh+ A and Rh B A Rh+ A Rh+
AB Rh+ A Rh -
0 Rh+
0 Rh -
A Rh - A B A Rh - A Rh -
(Can develop Rh A Rh+ 0 Rh -
antibodies) AB Rh -
AB Rh+
B Rh+ B and Rh A B Rh+ B Rh+
AB Rh+ B Rh -
0 Rh+
0 Rh-
B Rh - B A B Rh- B Rh -
(Can develop Rh B Rh+ 0 Rh -
antibodies) AB Rh-
AB Rh+
0 Rh+ Rh A and B 0 Rh+ 0 Rh+
A Rh+ 0 Rh -
B Rh+
AB Rh+
0 Rh - None A and B (Can AB Rh+ 0 Rh -
develop Rh AB Rh -
antibodies) A Rh+
A Rh -
B Rh+
B Rh -
0 Rh+
0 Rh -
article source : nobelprize.org
