Pg 145
The four different blood groups
A
B
AB
O
The four different blood groups
• The proteins found on the surface of the RBC
are also known as antigen.
Note: These antigens do not stimulate the
lymphocytes to produce antibodies.
The four different blood groups
• Classification of blood types are based on the
type of antigens found on the surface of red
blood cells.
‘Natural antibodies’
• Natural antibodies found in our blood.
Natural antibodies
Antibodies
Occurs naturally and
Produced only in the
always present in the body. presence of foreign objects
like bacteria/virus.
• Antigens react with antibodies.
Agglutination of blood
• Clumping / agglutination of blood occurs
when:
– Antigen A reacts with antibody a
– Antigen B reacts with antibody b
Agglutination of blood
• Blood clumps block up small blood vessels and
obstruct the flow of blood.
What happens when different blood
groups are mixed in blood transfusion?
• Blood donors
• Blood receivers
• Agglutination of donor’s RBCs
Why is blood group AB called the
universal acceptor?
• Absent of antibodies in the plasma.
• No reaction with antigens on other RBCs.
• “AB – sounds like acceptor”
Why is blood group O called the
universal donor?
• No surface antigen on blood group O.
• Will not react with natural antibodies in other
blood group.
• Antibodies a and b in the donor’s plasma
would be diluted by the recipient's blood.
• Hence no effects of the antibodies on the
recipient's RBC.
In summary
Blood group
A
B
AB
O
Receive blood
from
A,O
B,O
A,B,AB,O
O
Testing for blood group
Unknown X
Check for
Agglutination
Antigen A – antibody a
Antigen B – antibody b
Antibody A
Antibody B
Test Yourself [pg145]
a)
X – Blood group B
Y – Blood group AB
Z – Blood group O
b) Serum from A contains antibody B.
reacts with antigen B found on RBC to cause
clumping.
Test Yourself [pg145]
C) Blood group O
d) A, AB
e) No surface antigen to cause agglutination of RBC.
Antibodies a and b in the donor’s plasma would be
diluted by the recipient's blood.
Hence antibodies has no effects on the recipient's
RBC.