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Blood Groups and Blood
Transfusion
TEXTBOOK OF MEDICAL PHYSIOLOGY
GUYTON & HALL 11TH EDITION
UNIT VI CHAPTERS 35
Dr.Salah Elmalik
Department of Physiology
College of Medicine
King Saud University
Objectives
At the end of this lecture student
should be able to:
1. Describe ABO blood group types
2. Recognize Agglutinins in plasma
3. Recognize transfusion (cross) reactions
4. Describe Rhesus blood groups.
5. Describe causes of hemolytic disease of
the newborn.
Human Blood Groups
• RBC membranes have glycoprotein antigens on
their external surfaces.
• Human erythrocytes has >300 antigenic
determinants
• These antigens are:
– unique to the individual
– promoters of agglutination and are referred to as
agglutinogens
– recognized as ‘foreign’/non-self if transfused into
another individual
• Presence or absence of these antigens is
used to classify blood groups
3
Markers on RBC
• Agglutinogens = antigens
that promote gglutination
– A B O – 2 glycoprotein
antigens, A and B
– Rh
– Duffy; Kidd; Kell; Lewis
The ABO System
Discovered in 1901 by Dr. Karl Landsteiner
4 main phenotypes (A, B, AB, O)
ABO gene located on long arm of
chromosome 9.
Antigens/agglutinogens Type A and Type
B on the surface of the RBCs are the
cause of blood transfusion reactions [BTR]
Thus, the presence or absence of these
Ag’s is the essential basis that blood is
grouped for the purpose of transfusion.
The ABO Blood groups
GroupBlood
Agglutinogen
Agglutinin
A
A
Anti-B
B
B
Anti-A
AB
A & B
-
O
-
Anti A+B
Inheritance of blood groups
Blood group
A
B
O
AB
Genotypes
AA, OA
BB, OB
OO
AB
Relative frequencies of the different blood types:
O
A
B
AB
47%
41%
9%
3%
Phenotype V. Genotype
Phenotype: individual’s outward characteristics
Genotype: individual’s pair of allele genes
together
Example:
Phenotype
Blood type B
Genotype
Could be BO or
BB depending on
parents
The ABO system- cont.
• Anti-A & Anti-B are:
naturally occurring antibodies.
• Not present at birth, appear 2-8/12
• Triggered by A & B antigens in food
and bacteria
Antigens & Antibodies in the
ABO system
Blood Group
Antigens on
RBCs
Antibodies in Serum
Genotypes
A
A
Anti-B
AA or AO
B
B
Anti-A
BB or BO
AB
A and B
Neither
AB
O
Neither
Anti-A and anti-B
OO
The ABO system- cont
• Because type O lacks Ags, type O blood does not cause an
immune response.
• This is why type O blood cells can be given to patients of any
blood type. People with type O blood are called "universal
donors."
• However, people with type O can only receive type O blood.
• Type AB has both Ag A & B but lack antibodies so can receive
blood from other groups and therefore they are called
(Universal Recipients)
12
THE Rh SYSTEM
– Discovered by Landsteiner & Wiener in
1937
– Antigen discovered in the Rhesus monkey
– Rh is an Ag on the RBC
•
•
•
•
a. Rh+ has the Ag (85% of the population)
b. Rh- does NOT have the Rh antigens
c. Rh+ can accept Rh+ or Rh- blood
d. Rh- can accept ONLY Rh- blood
Rhesus (Rh) Blood Group
Determined by:
• Presence or absence of the Rhesus
antigen (D) on the surface of RBC:
– Presence of D (individual is Rh+ve)
– Absence of D (
‘
‘ ‘ Rh–ve)
• Rhesus antigens:
Dd, Cc, Ee
Clinically most important is D
Rhesus (Rh) Blood Group
Anti-D antibody (agglutinin):
-Is not naturally-occurring
-Can be acquired by:
i-Transfusion of Rh-ve individual
with Rh+ve blood
ii-Rh-ve pregnancy with Rh+ve faetus.
Importance of blood groups
1. Blood Transfusion.
2. Rh incompatibilty between
mother and fetus
Agglutination in transfusion reaction
• If a patient of blood group A
transfused with blood of group B
• The anti-B in plasma will agglutinate
the transfused group B cells.
Outcome:
– The clumped cells plug small blood
vessels (kidney shut down)
– Sometimes immediate hemolysis
Transfusion reactions
(Incompatible Blood transfusion)
• If a person with blood group B transfused
with blood of group AThe anti-A in plasma
of recipient blood group B will agglutinate
the transfused cell (A)
• The clumped cells plug small blood vessels
• Sometimes causes immediate hemolysis
Transfusion reaction
Complications of blood transfusion
1. Immune reaction: Incompatible blood
transfusion leading to immediate or
delayed reaction, fever, hemolysis,
allergic reaction
2. Transmission of infection; malaria,
syphilis, viral hepatitis & Aids
3. Iron overload
Blood tests before transfusion
1. Blood group type of patient (recipient)
2.
Cross-matching
Blood tests before transfusion
1. Blood group type of patient (recipient)
2.
Cross-matching
Blood tests before transfusion
1. Blood group type of patient (recipient)
A drop of
patient
RBC
Anti-A
Anti-B
• Look for agglutination
Anti-D
Agglutination Reaction
Blood tests before transfusion
RBC
Anti A
Anti-B
O
-
-
A
+
-
B
-
+
AB
+
+
Blood tests before transfusion
1. Blood group type of patient (recipient)
2.
Cross-matching
Blood tests before transfusion
2.
Cross-matching:
donor cells
+
recipients (patient)
serum
Rh incompatibilty
between
mother and fetus
Rh incompatibilty between mother
and fetus
• Mother Rh-ve first Rh+ve baby:
• At delivery
– Fetal Rh+ RBC cross to maternal
blood
• The mother will develop Anti-D
after delivery.
• First child escapes & is safe
(If the mother is transfused with Rh+ve blood
before, first child will be affected)
Rh incompatibilty between mother
and fetus-cont.
• Second fetus
– If Rh+ve
– Anti-D crosses placenta and
destroys fetal Rh+ RBC
– Outcome?
Hemolytic Disease of the
newborn
Hemolytic Disease of the
newborn
1. Hemolytic anemia:
– If severe:
treated with exchange transfusion:
Replace baby blood with Rh-ve RBC
(several times)
2. Hydrobs fetalis (death in utero)
Hemolytic Disease of the
newborn-cont.
Prevention:
•
Injecting the mother with anti-D
immediately after 1st childbirth
•
Antenatal
(during pregnancY)
prophylaxis
Anti-D