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Welcome to the Clinical Laboratory
BLOOD BANK
To learn about Blood
Bank!
Why Study Blood Banking?
 Blood Bank is the area of the lab that
prepares units of blood for patient
transfusion.
 Blood Bank also:
Identifies and treats mothers and babies with Hemolytic
Disease of the Newborn (HDN). This is the condition
which results from the mother being Rh negative and the
baby being Rh positive.
 Performs paternity testing

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Many Different Blood Components are Given
by the Blood Bank
 All must be tested for multiple infectious diseases.
 All have expiration dates, because these are living products.
 All have preservatives and anticoagulants.
 Given for different reasons:
To increase hemoglobin – Packed Red Cells
 To replace multiple coagulation deficiencies after massive
transfusions - Whole Blood and/or volume expanders
 To increase platelet count – Separated Platelets

Blood Components Given by the Blood Bank
 Whole Blood: Has RBC, WBC, Platelets, Plasma,
preservatives

&
Approx. 500 ml (450 ml blood + 70 ml
anticoagulant/preservative) costs at least $550.
 Packed Red Cells: RBCs, and preservatives, to
replenish RBCs

One unit is approximately 250 ml.
 Fresh Frozen Plasma: Plasma & preservatives,
To replenish coagulation factors such as Factor
VIII (hemophiliacs are deficient in Factor VIII
and can bleed to death without treatment.)
Components Given by the Blood Bank
 Washed or Irridiated Red Blood Cells: packed
RBCs that have been washed irradiated.
 To decrease or eliminate the response of the
transfused T cells (lymphocytes).
 Given to the immuno-incompetent such as
chemotherapy patients.
 Platelets: To raise platelet count approx. 50,00080,000 in cases where disease has eliminated
platelets specifically.
Other unit types
 Autologous units
 From
individuals who have donated a unit of
blood product for their own use only; typically
used for generally healthy patients who have an
elective surgery such as a total knee replacement.
Directed units
 From individuals who have
donated a unit of blood product
for a specific person; should be
type specific.
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Work Done in Blood Bank Involves Knowledge of the
Immune System
 The immune system protects the body from
potentially harmful substances by recognizing and
responding to antigens. Antigens are molecules
(usually proteins) on the surface of cells, viruses,
fungi, or bacteria.
 Nonliving substances such as chemicals, drugs,
and foreign particles (such as a splinter) can also
be antigens. The immune system recognizes and
destroys substances that contain these antigens,
generally by producing antibodies.
Antigens (Ag) That are Important in Blood
Bank
 Antigens - protein on a RBC surface which, when foreign to
the person, can stimulate production of antibodies
 Complex structure of: complex carbohydrates and/or
proteins
 Antigens (Ag) studied in blood bank are found on: red blood
cells, white blood cells, platelets
 Normally, a person does NOT produce an antibody to an
antigen they own (this is very important!)
Simplified Mechanism of an Immune Response
 First, recognition of the foreign substance (self vs
foreign)
 Second, destruction and removal of foreign
substance. When antibodies attach to antigens, the
resulting cell is targeted to be removed.
 Third, repair of total system.
Antibodies (Ab)
 Antibody (Ab) - protein that is produced
in response to exposure to a foreign
antigen; located in plasma/serum.
 Function is to deactivate the antigen
 First
there’s the antigen, then, if it’s foreign, an
antibody is produced by the immune system.

(There are some antibodies that are studied in Serology that are of
interest because they are evidence of disease. Sometimes diagnoses are
made solely on evidence of the antibody to the antigen that caused the
disease. This is how Lyme Disease is diagnosed)
Immune System
Two basic mechanisms of immune system (again):
 To recognize foreign or abnormal substances
 To respond by enlisting various reactions to eliminating
that substance (immune response, generally involving
antibodies)
Types of antibodies – these are different sizes and shapes, so
have different purposes
 IgG
 IgM
 IgA
Within blood bank (immunohematology) pregnancy and
transfusion are the relevant sources of antibody stimulation.
Purpose of Immune System
 To protect against pathogens and foreign
substances (defense mechanism)
 To identify malignant, aged/imperfect cells, and
those infected by virus, bacteria, parasites, or cells
coated with Ab.
 To remove abnormal or damaged cells, like those
above
 Basically, to protect us.
Immune Response – why are antibodies
produced?
 Immunogenicity is the ability of an Antigen to
stimulate the production of its corresponding
Antibody in a person lacking that Antigen.
 Some antigens have a stronger ability to
stimulate antibodies than others . This is called
immunogenicity.
 Antibodies are very specific to the antigen.
Why Are These Reactions Even Studied in Blood
Bank
These RBCs are circulating as
they should.
If we could see their antigens on the
surface, this might be what it would
look like.
Antigen/Antibody Reaction
But when antibodies attach
to the surface antigens,
cells clump. Now imagine
how that clumping affects
circulation.
Both the clumping and
the hemolysizing of cells kill
the patient.
Antigen/Antibody Reaction
Clumped cells
Antigen-Antibody Reactions
 In the previous slide, the immune system was
stimulated and antibodies were produced.
 What we try to do in Blood Bank is mimic the
conditions of blood transfusion in the lab before the
blood is given (in vitro), so that there is no immune
response to the transfusion needed, thus, preventing
an antigen-antibody reaction from occurring in the
live patient (in vivo.)
 Reactions are very rapid and often deadly, so work
done in Blood Bank is very critical.
Blood Groups
 Most people associate blood groups with what blood
type someone is, for example O positive, A negative,
B positive, etc... That assumption only accounts for
two blood groups: ABO and Rh blood groups. There
are many blood groups with various antigens
associated with each.
 We will only talk about A, B, O, AB, and Rh groups
because they are the most common with the strong
immunogenicity.
How Blood Groups Work
 Type A people have A antigens on their RBC and B
antibodies in their plasma
 Type B people have B
antigens on their RBC and
A antibodies in their plasma.
 Type O people have neither A
nor B antigens on their cells but
have both antibodies in their
plasma.
 Type O people have neither A or B antigens on their RBC ,
but they have A and B antibodies in their plasma.
 Type AB people have both A and B antigens on their RBC,
and no A or B antibodies in their plasma.
Another View of Antigen/Antibody Reaction
The reaction pulls
the cells closer,
causing clumping.
Clumped cells do not
circulate well.
Crossmatching for Transfusions
 Crossmatching the patient’s blood with a sample of
the unit to be transfused is done in blood bank to be
certain the transfusion will be compatible.
 If the blood given is compatible the with patient, this
is called a compatible transfusion and all is well.
This means the patient hasn’t received blood with
antibodies against any antigens present.
 Crossmatching is very, very important and is always
performed carefully and documented scrupulously.
Transfusions (cont.)
 But if the patient receives a unit of blood with
antibodies matching antigens present, the
antibodies attach and begin destroying the cells
(remember, the immune system gets rid of imperfect
cells.)
 This kind of transfusion is called an incompatible
transfusion. If the antigen/antibody reaction
involves group A, B, O, AB, destruction of the cells is
immediate and often the patient dies quickly.
The Crossmatch
 Again, all of this is tested for in the blood bank.
 A very simple explanation of a crossmatch:
 adding antisera (the antibody) to the patient’s cells
where the antigens will be, if present.
 If there is an antigen/antibody reaction, the cells
clump (because the antibodies have attached to the
antigens).
The blue liquid
is the anti-A
antisera.
See the clump?
clump?
The Crossmatch
This is what happens in an incompatible crossmatch:
Crossmatch (in vivo)
Incompatible blood.
See the clumping?
Compatible blood
A Bit More About Blood Groups
 At the beginning of the 20th century an Austrian scientist, Karl Landsteiner,
noted that the RBCs of some individuals were agglutinated by the serum from
other individuals. He made a note of the patterns of agglutination and showed
that blood could be divided into groups. This marked the discovery of the first
blood group system, ABO, and earned Landsteiner a Nobel Prize.
 Karl Landsteiner and Alexander Wiener injected animals with Rhesus monkey
cells to produce an antibody which reacted with 85% of human red cells, which
they named anti-Rh. Later, it became obvious that there were more antigens in
the Rh monkey blood (see next slide!)
 A blood group contains antigens controlled by a single gene. At the time of
writing, there are 22 blood group systems, including the ABO, Rh, and Kell
blood groups which contain antigens that can provoke the most severe
transfusion reactions.
A Bit More About Blood Groups
 ABO Blood Group: 4 antigens: A, B, AB, and A1
 Rh Blood Group: 49 antigens, but D, C, E, c, and e
are among the most significant.
 But, when someone is said to be Rh positive, most of
the time this means they have the D antigen.
Hemolytic Disease of the Newborn
 HDN is a condition where the mother is Rh-, the
father is Rh+ and the baby is Rh+.
 The mother's immune response to the fetal D antigen
causes antibodies to form against it. These
antibodies are usually transported across the
placenta and become part of the fetal circulation.
This is when they attach to the baby’s D antigen.
 Remember, some of these reactions cause
destruction of the red cell (hemolysis). The baby can
be in a life threating situation without treatment.
Treating HDN
HDN blood cells
The mother is most likely to be exposed
to the baby’s blood the last three weeks
of pregnancy. So that this type of reaction
doesn’t happen, a pharmaceutical
named RhoGam is given to the mother.
RhoGam contains Anti-D, so if the
mother does get the baby’s blood with
its D-antigens, the RhoGam antibodies
will attach, making the baby D-antigen
unable to stimulate an antibody.
To recap, the mother has anti-D that wants to
attach to the baby’s D antigen should the two
bloods mix.
To keep this from happening, RhoGam, a
manmade D antigen is given to the mom to bind
her anti-D.
Review Questions
 In Blood Bank, is only one product transfused to the




patient? List as many as you can.
The concept of self and foreign material is important
in immunology. What do these two terms, self and
foreign mean?
True or false: ABO and Rh are the only two blood
groups.
What is the process of confirming compatiblity units
of blood for the patient called?
If the patient is A positive, they have A-antigens and
what type of antibodies?
Review Questions
 When crossmatching, what does an incompatible
unit look like?
 What is the treatment preventing Hemolytic Disease
of the Newborn called?
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