Download 2.Rh Blood Type

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Lec. 11
2016
Blood Grouping
Objectives:
1.ABO System
 ABO Transfusion Reaction
2.Rh Blood Type
 Rh transfusion reaction
The antigens on the surface of erythrocytes have been categorized
into blood groups and more than 35 blood groups, most of which are rare,
have been identified. The ABO blood group and Rh blood group are
among the most important. Other well known blood group includes
Lewis, Duffy, Kidd, Kell, Lutheran, and MNSs. ABO and Rh-blood
groups of antigens are more likely than the others to cause blood
transfusion reactions.
ABO Blood Systems
Agglutinogens The membrane of human red cells contains a variety of
blood group antigens, which are also called agglutinogens. The most
important and best known of these are the A and B antigens, The A. and
B antigens are actually complex oligosaccharides that differ in their
terminal sugar. The A and B antigens are inherited as Mendelian
dominants and individuals are divided into four major blood types
depending on the presence or absence of the A antigen, and B antigen
1. Type A. 2. Type B. 3.Type AB. 4. Type O. Subgroups of blood
types of A and B have been described, the most important being A1 and
A2.These antigens are also found in many tissues in addition to blood,
these include salivary glands, saliva, pancreas, kidney, liver, lungs, testes,
semen and amniotic fluid.
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Agglutinins (Antibodies): Antibodies against red cell agglutinogens are
called agglutinins which are present in the plasma. The agglutinins are
gamma globulins and they are produced by plasma cells (which are
originated from B-lymphocytes) system. Most of them are IgM (have 10
binding sites) and IgG (have two binding sites).The presence of A and B
antibodies in the blood is not clearly understood. An infant develop
antibodies against the antigens not present in their own cells.
The type of agglutinogen, agglutinin, and frequency (%) in each type
of :
1. Blood group A: has A antigens on the erythrocytes and
antibodies B in the plasma .The percentage (%) of this group is 41
blood group.
2. Blood group B: has antigens B on the erythrocytes and
antibodies A in the plasma. The % is 10.
3. Blood group AB: has both types of antigens A and B on
the erythrocytes and has neither type of agglutinins in the
plasma. The % is 4.This group is called Universal Recipient
(a recipient receives the blood). Blood AB group receives the
blood from all groups but cannot give blood to any type except
a person of blood group AB.
4. Blood group O: has neither A nor B agglutinogens in the
plasma. The % is 45. This group is called Universal Donor (a
donor gives blood). Blood group O gives blood to all but can't
receive blood except from person of blood group O.
Table: blood groups their agglutinogens, agglutinins , and %.
Blood group Agglutinogens Agglutinins
%
O
Anti-A, Anti-B
45 Universal donor
A
A
Anti-B
41
B
AB
B
A,B
Anti-A
-
10
4 Universal recipient
ABO Transfusion Reactions
Transfusion: is the transfer of blood or other solutions from the donor
into the blood of patient (or recipient). Transfusion reaction or
agglutination (clumping): is the reaction between agglutinogens on the
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donor's red blood cells and agglutinins in the recipient's plasma.
Dangerous hemolytic transfusion recipients occur when blood of donor
transfused into an individual with an incompatible blood type. For
example a person with type A blood would denote to another person with
type A blood because there would be no ABO transfusion reaction, the
recipient has no antibodies against the type A antigens. Also person with
type A can give blood to a person with type AB and no agglutination.
Blood group A can receive blood only from type A and O.
On the other hand if type A blood is donated to a person with type B,
there would be a transfusion reaction because the person with type B
blood has agglutinins against type A-agglutinogens and agglutination
would result.
Person with type O are called “universal donor” can be given to
anyone without producing a serious transfusion reaction due to ABO
incompatibility, because they lack antigens A&B. for example if type O
blood is given to a person with type A or type B blood, the type O
erythrocytes don not react with type B antibodies or type A antibodies
respectively in the recipient’s blood.
Person with type AB blood are called “universal recipient” because
they have no circulating agglutinins & can give blood of any type
without developing a serous transfusion reaction. Type AB blood does
not have antibodies against A or B antigens. Therefore type AB blood
could receive blood for any type of blood without developing transfusion
reaction. The clumping of RBC s is occurred by the following process:
the binding sites of agglutinins can attach to more than two RBC’s at the
same time there by causing the cells to adhere to each other. As a result
clumping of RBC’s occurs. Then these clumps plug small blood vessels
& hemolysis of cells occurs, Hb is liberated into the plasma & the level of
bilirubin rise and renal damage with anuria and death. So one of he
most lethal effects of transfusion reaction is kidney shutdown and the
person dies of renal failure.
Table 2 shows the compatibility & incompatibility between donors &
recipients blood transfusion.
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Table 2: The compatibility & incompatibility between donors &
recipients blood transfusion.
Recipient
Donor
Type A
Type B
Type AB
Type O
Type A
-
+
+
-
Type B
+
-
+
-
Type AB
-
-
-
-
Type O
+
+
+
-
- No agglutination
+ Agglutination
Indications for Transfusion:
1. The most common reason for transfusion is decreased blood volume.
2. Treating anemia or to supply the recipient with some other constituent
of whole blood besides red blood cells, such as to supply a
thrombocytopenic patient with new platelet
3. Hemophilic patients can be rendered temporarily non-hemophilic by
plasma transfusion.
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Rh-Blood Group
Rh-Blood groups: Another important blood group is the Rh-system is
also important in the transfusion of blood. The Rh-factor named for the
rhesus monkey because it was first studied using the blood of this
animal.
Rh-agglutinogens:: there are six common types of Rh-antigens each
of which is called Rh-factor. These types are C, D, E, c, d, & e.The type
D (Rh)-antigen is widely prevalent in the population. Therefore anyone
who has this type of antigen on RBC membrane is said to be Rh-positive
(Rh+) or D-positive (D+) about 85% of population are Rh+, while
persons who does not have antigen D on their RBC is said to be Rhnegative (Rh-) or D- & about 15% are D- (Rh-). Rh+ is dominant while
Rh- is ressive.
Rh-agglutinins: The Rh+ individual has no antibody in their plasma. The
Rh- person has also no antibody D in the plasma, but Rh - individual forms
the antibody –D when injected with D+ (Rh+) cells. Antibodies against
Rh-antigen do not develop unless an Rh- person is exposed to Rh+blood. This can occur through a transfusion or entrance of fetal blood
into the maternal circulation across the placenta.
Table 3 demonstrates Rh –type, agglutiongen, agglutinin, and % of each
Rh –group.
Table 3: Rh –type, agglutiongen, agglutinin, and % of each
Rh group.
Rh-type
Agglutinogen on RBC
Agglutinins in plasma
Rh+
D
--
%
85
6
Rh-
--
--
15
The ABO blood type & the Rh -blood type usually are designated
together.
(ABO-system) (Rh-system).
For example a person designated as A positive (A+) is blood group A in
the ABO- system and Rh+ in the Rh blood group. This person has
antigens A & D on RBC & antibody-B& no antibody-D in the plasma.
Rh –Transfusion Reaction
Example: Hemolytic disease of newborn (HDN) or erythroblastosis
fetalis.Fetus may develop hemolytic anemia in two major ways a
consequence of developing antibodies.
1. Rh- incompatibility.
2. ABO- incompatibility
A.HDN due to Rh-incompatibility
Rh –Transfusion Reaction: is the reaction between antigen -D in Rh+
blood of donor & antibody D in Rh- blood of recipient. When an Rhreceives a first transfusion of Rh+ blood, the recipient becomes sensitized
to the Rh+ antigen & produces antibodies D. If the same person is
unfortunate receive a second transfusion of Rh+ blood, reactions results &
clumping of RBC’s occurs.
Hemolytic disease of newborn (HDN) or erythroblastosis
fetalis:HDN: is a disease of he fetus & neonate characterized by
agglutination between antigen D in the fetus & antibody D produce
by the mother can pose a major problem in some pregnancies when the
mother is Rh- antigen ,the father is Rh+ and fetus is Rh- The baby has
inherited the Rh + antigen from the father i.e. if an Rh- female marries an
Rh+ male, she has 50% of producing an Rh+ fetus if father is heterozygous
(Rh+Rh-).
Mother Rh- (Rh- Rh -)
X
father+ (Rh+ Rh-) heterozygous
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Fetus : 50% Rh+ (Rh+ Rh-) , 50%Rh – (Rh – Rh –)
A 100% chance of producing an Rh+ fetus if the father is homozygous
(Rh+ Rh+).
Mother (Rh- Rh-)
X
father (Rh+ Rh+) homozygous
Fetus:
100% Rh+ RhDuring pregnancy the maternal & fetal circulation are separate. At the
time of delivery small amount of fetal blood which contain antigen D leak
into the maternal circulation & some mother develop antibody D
during postpartum period. In the woman’s first pregnancy there is no
problem. The leakage of fetal blood which contain antigen D is usually
the result of a tear in the placenta that takes place during delivery. Thus
there is no enough time for the mother to produce enough to form Dantibodies to harm the fetus. In the later pregnancies, a problem can
arise because the mother has been sensitized (i.e. forming antibody-D)
against antigen D in the fetus. When the mother becomes pregnant
again with another Rh+ fetus, and if there is any leakage of fetal blood
into the mother’s blood through the placenta she rapidly produce large
amounts of Rh-antibodies & HDN develops in the fetus. The term
erythroblastosis fetalis is also used to describe HDN since blood smears
from these babies show the presence of many immature red blood cells or
erythroblasts.
Figure 1:hemolytic disease of newborn(HDN).
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Prevalence of disease: an Rh negative mother having her first Rh –
positive child usually does not develop sufficient anti – D to cause any
harm. About 3% of second Rh –positive babies exhibit some signs of
HDN; 17% of the third babies exhibit the disease; and the incidence rises
progressively with subsequent pregnancies. About 50% of Rh negative
individuals are sensitized (develop an anti-Rh titer) by transfusion of Rh+
blood.
Symptoms of disease:
1. severe jaundice 2. Odema (hyrops fetalis).
3. Kernicterus due to deposition of bilirubin in the basal ganglia which
result in brain damage & mental retardation. 4. Splenomegaly &
hepatomegaly (i.e. enlargement of spleen & liver).
Treatment of HDN
1.Treatment of mother: The Rh- woman should be given an injection
of single dose of anti-D antibodies which is called Rho(D) immune
globulin (RhoGAM) within 72 hours during the postpartum period
or during pregnancy or immediately after each abortion. The injection
contains anti-D against antigen-D.The injected antibodies will bind to
Rh – antigens of fetus erythrocytes that may have entered the
mother's blood and destroy the antigen D on fetal RBC before the
immune system of the mother is activated. In other words, the fetal
RBC s will be destroyed before the mother is able to develop her own
antibodies against these erythrocytes. Hence she will be able to
conceive another Rh+ child without any complication.
2.Treatment of erythroblastic neonate: 1. By exchange transfusion
i.e. slowly removing the newborn’s blood & replacing it with Rh —
blood to reduces the level of maternal antibody-D, which thereby
decreases the level of fetal RBC hemolysis. 2. Exposure of newborn to
fluorescent light to breakdown the large amount of bilirubin formed
as a result of erythrocyte destruction. High levels of bilirubin are toxic
to the nervous system and can damage brain tissues.3.In addition fetal
Rh-typing with obtained material by amniocentesis or choronic
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villus sampling is now possible and treatment with a small dose of Rh
immune serum will prevent sensitization during pregnancy.
Blood
B. HDN due to ABO-incompatibility: when a mother of type O blood
becomes pregnant & the fetus has type A or B antigens on RBC this
may result in anemia known as HDN. The ABO-HDN is the more
common that Rh-HDN. Approximately 23% of all pregnancies involve
incompatible ABO system.