Blood Groups, Blood Typing and Blood Transfusions
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.
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 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 platelets help the blood to clot, if you get a wound for example.
The plasma contains salts and various kinds of proteins.
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 blood group (in 1901) and Rh blood
group (in 1937).
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-
|
Do you know which blood group you
belong to?
Blood
typing – how do you find out to which blood group someone belongs?
1.
You mix the blood with three different reagents including either of the three different antibodies, A, B or Rh antibodies.
You mix the blood with three different reagents including either of the three different antibodies, A, B or Rh antibodies.
2.
Then you take a look at what has happened. In which mixtures has agglutination occurred? The agglutination indicates that the blood has reacted with a certain antibody and therefore is not compatible with blood containing that kind of antibody. If the blood does not agglutinate, it indicates that the blood does not have the antigens binding the special antibody in the reagent.
3.
If you know which antigens are in the person's blood, it's easy to figure out which blood group he or she belongs to!
Then you take a look at what has happened. In which mixtures has agglutination occurred? The agglutination indicates that the blood has reacted with a certain antibody and therefore is not compatible with blood containing that kind of antibody. If the blood does not agglutinate, it indicates that the blood does not have the antigens binding the special antibody in the reagent.
3.
If you know which antigens are in the person's blood, it's easy to figure out which blood group he or she belongs to!
A person with A+ blood
receives B+ blood. The B antibodies (yellow) in the A+
blood attack the foreign red blood cells by binding to them. The B antibodies
in the A+ blood bind the antigens in the B+ blood and
agglutination occurs. This is dangerous because the agglutinated red blood
cells break after a while and their contents leak out and become toxic.
|
What
happens when blood clumps or agglutinates?
For a blood transfusion to be
successful, AB0 and Rh blood groups must be compatible between the donor blood
and the patient blood. If they are not, the red blood cells from the donated blood
will clump or agglutinate. The agglutinated red cells can clog blood vessels
and stop the circulation of the blood to various parts of the body. The
agglutinated red blood cells also crack and its contents leak out in the body.
The red blood cells contain hemoglobin which becomes toxic when outside the
cell. This can have fatal consequences for the patient.
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The A antigen and the A antibodies can bind to each other in the same way that the B antigens can bind to the B antibodies. This is what would happen if, for instance, a B blood person receives blood from an A blood person. The red blood cells will be linked together, like bunches of grapes, by the antibodies. As mentioned earlier, this clumping could lead to death.
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The A antigen and the A antibodies can bind to each other in the same way that the B antigens can bind to the B antibodies. This is what would happen if, for instance, a B blood person receives blood from an A blood person. The red blood cells will be linked together, like bunches of grapes, by the antibodies. As mentioned earlier, this clumping could lead to death.
Blood
transfusions – who can receive blood from whom?
Of course you can always give A
blood to persons with blood group A, B blood to a person with blood group B and
so on. But in some cases you can receive blood with another type of blood
group, or donate blood to a person with another kind of blood group.
The transfusion will work if a person who is going to receive blood has a blood group that doesn't have any antibodies against the donor blood's antigens. But if a person who is going to receive blood has antibodies matching the donor blood's antigens, the red blood cells in the donated blood will clump.
The transfusion will work if a person who is going to receive blood has a blood group that doesn't have any antibodies against the donor blood's antigens. But if a person who is going to receive blood has antibodies matching the donor blood's antigens, the red blood cells in the donated blood will clump.
People with blood group 0 Rh -
are called "universal donors" and people with blood group
AB Rh+ are called "universal receivers."
Rh+ blood can
never be given to someone with Rh - blood, but the other
way around works. For example, 0 Rh+ blood can not be given
to someone with the blood type AB Rh -.
|
Blood
Group
|
Antigens
|
Antibodies
|
Can
give blood to
|
Can
receive 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
(Can develop Rh antibodies) |
AB Rh -
AB Rh+ |
AB Rh -
A Rh - B Rh - 0 Rh - |
A Rh+
|
A and Rh
|
B
|
A Rh+
AB Rh+ |
A Rh+
A Rh - 0 Rh+ 0 Rh - |
A Rh -
|
A
|
B
(Can develop Rh antibodies) |
A Rh -
A Rh+ AB Rh - AB Rh+ |
A Rh -
0 Rh - |
B Rh+
|
B and Rh
|
A
|
B Rh+
AB Rh+ |
B Rh+
B Rh - 0 Rh+ 0 Rh- |
B Rh -
|
B
|
A
(Can develop Rh antibodies) |
B Rh-
B Rh+ AB Rh- AB Rh+ |
B Rh -
0 Rh - |
0 Rh+
|
Rh
|
A and B
|
0 Rh+
A Rh+ B Rh+ AB Rh+ |
0 Rh+
0 Rh - |
0 Rh -
|
None
|
A and B (Can develop Rh
antibodies)
|
AB Rh+
AB Rh - A Rh+ A Rh - B Rh+ B Rh - 0 Rh+ 0 Rh - |
0 Rh -
|
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