Blood Typing
What is the use of blood typing?
• Each person’s blood is different due to the presence
of antigens on the surface of red blood cells.
• Before a person receives a blood transfusion it is
important to do blood typing.
• Doctor’s must be sure that the donated blood is
compatible with the recipients blood.
• Mixing blood types can be very dangerous, even
deadly in some cases.
What is blood made up of?
An adult human has about 4–6 liters of blood
circulating in the body.
Blood consists of several types of cells floating
around in a fluid called plasma.
The red blood cells (RBCs) contain
haemoglobin, a protein that binds oxygen. RBCs
transport oxygen to, and remove carbon dioxide
from the 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.
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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
RBCs and the antibodies are in the blood
plasma.
•Individuals
have
different
combinations of these molecules.
types
and
•The blood group you belong to depends on
what you have inherited from your parents.
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What are the different blood groups?
• There are more than 20 genetically determined
blood group systems known today
• The AB0 and Rhesus (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, which is dangerous for individuals.
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ABO blood grouping system
According to the ABO blood
typing system there are four
different kinds of blood types:
A, B, AB or O (null).
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Type A Blood
• If you belong to the blood group A, you
have A antigens on the surface of your
RBCs and B antibodies in your blood
plasma.
• A person with type A blood may only donate their
blood to another person with type A blood or
someone who has type AB blood.
Type B Blood
• If you belong to the blood group B, you have
B antigens on the surface of your RBCs and A
antibodies in your blood plasma.
• A person with type B blood can only donate blood to
another person with type B blood or someone who has
type AB blood.
Type AB Blood
• Type AB blood has BOTH A & B antigen and does not
contain ANY antibodies.
• For this reason type AB blood is considered the
universal recipient.
– Since type AB blood has no antibodies against the
other blood types, a person with type AB blood
can receive any type of blood if needed, but may
only donate blood to other type AB recipients.
Type O Blood
• Type O blood has neither an A or a B antigen and
contains both A AND B antibodies.
• Because type O blood does not have either antigen it will
not react with A or B antibodies so a person with type O
blood may donate blood to any other blood types. For
this reason type O blood is known as the universal donor.
• Type O will attack all other blood types (A,B, & AB) so a
person with type O blood may only receive blood from
another person with type O blood.
Diagram of how different blood types may
donate:
Blood
Group
Antigens
Antibodies
Can give
blood to
Can receive
blood from
AB
A and B
None
AB
AB, A, B, O
A
A
B
A and AB
A and O
B
B
A
B and AB
B and O
O
None
A and B
AB, A, B, O
O
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HOW TO KNOW YOUR BLOOD TYPE
1. 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!