IMMUNOHEMATOLOGY REVIEW EXAM
QUESTIONS AND ANSWERS
List several blood group antigens of low incidence. - Correct Answers -C, W, V, Kp(a),
Js(a), Lu(a), M
List several high incidence blood group antigens. - Correct Answers -Kp(b), k, Js(b),
Lu(b), I
Which RBC antigens are not fully expressed at birth? - Correct Answers -A, B, I, P₁,
Lewis, and Lutheran
What is an antibody? - Correct Answers -An immunoglobulin that is produced in
response to stimulation by a specific antigen and is capable of combining with the
antigen that elicited its production. Antibodies are also known as agglutinins. They are
found in the plasma and serum.
What is an alloantibody? - Correct Answers -An antibody to a foreign antigen from
someone from the same species.
What is an autoantibody? - Correct Answers -An antibody to an antigen that one
possesses. Autoantibodies are usually only produced in disease states.
What is a naturally-occurring antibody? - Correct Answers -One that develops without
known antigenic stimulus, for example, anti-A and anti-B.
What is an immune antibody? - Correct Answers -One that results from exposure to a
foreign red cell antigen through transfusion or pregnancy.
If an untransfused male has an unexpected alloantibody, what type of antibody must it
be? - Correct Answers -A naturally-occurring antibody. An untransfused male has not
been exposed to foreign RBC antigens.
What are high-titer, low-avidity blood group antibodies? - Correct Answers -Antibodies
that cause weak, variable, and sometimes irreproducible reactions in the antiglobulin
phase at high dilutions. They are not clinically significant. Examples include anti-Ch, Rg,
JMH, Cs<sup>a</sup>, Kn<sup>a</sup>, McC<sup>a</sup>, Yk<sup>a</sup>.
Which immunoglobulin molecules are most frequently encountered in blood banking? -
Correct Answers -IgM and IgG.
,Compare the molecular structure of IgG and IgM and explain how their structures
affects their reactivity in blood bank testing. - Correct Answers -IgG is a monomer.
Because of its small size, it usually cannot agglutinate saline suspended in RBCs. A
potentiating medium or antiglobulin test is required. IgM is a pentamer. Because of its
large size, it is a potent agglutinator, even of saline-suspended cells at room
temperature, and it is an efficient activator of complement.
Which class of immunoglobulins is destroyed by sulfhydryl compounds like 2-
mercaptoethanol or dithiothreitol? - Correct Answers -IgM. These compounds break the
J chains that hold IgM together.
Which immunoglobulin class is most efficient at activating complement? - Correct
Answers -IgM
Which immunoglobulin class can cross the placenta? - Correct Answers -IgG
What is sensitization? - Correct Answers -The attachment of antibodies to antigens on a
red cell.
List several factors that affect hemagglutination. - Correct Answers -The sensitization
phase is affected by the temperature, the pH, the ionic strength of the medium, the
antigen-antibody ratio, and the time of incubation. The agglutination phase is affected
by the type of the antibody, the density and the location of the antigens, and the zeta
potential (electrostatic repulsion).
What are some potentiators that are used to enhance antigen-antibody reactions? -
Correct Answers -22% albumin, low ionic strength salt solution (LISS), and polyethylene
glycol (PEG).
What is the advantage of using LISS? - Correct Answers -It increases the rate at which
an antibody binds to red cell antigens so the incubation time can be shortened to 10
minutes.
What are two visible signs of an antigen-antibody reaction in blood bank testing? -
Correct Answers -Agglutination and hemolysis.
What causes hemolysis? - Correct Answers -The complement terminal membrane
attack unit, C5b, C6, C7, C8, and C9. This unit embeds in the cell membrane and forms
a hole. The loss of membrane integrity and the change in osmotic pressure within the
cell leads to cell death and lysis.
Explain the correct way to examine a tube for signs of an antigen-antibody reaction. -
Correct Answers -Following centrifugation, the tube should be gently shaken or tilted
until the cell button is completely dispersed. The manner in which cells come off the
button should be observed. An optical aid, such as an agglutination viewer with a light
and a magnifying mirror, should be used.
, In tube testing, how would three large agglutinates against a clear background be
graded? - Correct Answers -3+
In blood bank records, what must be recorded in addition to the degree of reactivity in
all phases of testing? - Correct Answers -Interpretation of the reactions<br>Identity of
the person who performed the tests<br>Date of the testing<br>Timely supervisor review
is required.
Why should serum separator tubes not be used for blood bank testing? - Correct
Answers -The gel can contaminate the RBCs during sampling and cause false-positive
test results.
Name two new methods that are being used in blood bank testing. - Correct Answers -
Column (gel) technology and solid phase red cell adherence (SPRCA). Both of these
methods can be automated.
Explain the principle of gel technology. - Correct Answers -Rather than using traditional
test tubes, cards containing microtubes are used. Each microtube contains gel particles
and a reagent specific for the test being performed. Following addition of serum or cells,
the cards are incubated and centrifuged. If agglutination has occurred, the agglutination
complexes are trapped in the gel; non-agglutinated cells settle to the bottom of the
microtube. Reactions are scored from 0-4+ depending on the disbursement of the red
cells in the microtube.
A gel microtube shows a well-delineated pellet at the bottom following incubation and
centrifugation. How should this reaction be graded? - Correct Answers -Negative.
A gel microtube shows a solid band of red cell agglutinates on the top of the gel
following incubation and centrifugation. How should this reaction be graded? - Correct
Answers -4+
What does a mixed field reaction look like in a gel? - Correct Answers -A band of red
cell agglutinates on top of the gel and a pellet of unagglutinated cells at the bottom of
the microtube.
What are the advantages of gel technology? - Correct Answers -Better standardization,
increased sensitivity, and clearer end-points. Tube shaking, cell washing, red cell
resuspension, and antiglobulin controls are not required. Reactions are stable for 24
hours. Gel technology can now be automated. Gels are available for antigen typing,
antibody detection and identification, and crossmatching.
Explain how antibodies are identified by solid phase adherence. - Correct Answers -The
patient's serum is added to microplate wells that are coated with a monolayer of reagent
blood cells. During incubation, if antibodies are present in the serum they will attach to
the corresponding antigens on the sides of the wells. The microplate is washed to
QUESTIONS AND ANSWERS
List several blood group antigens of low incidence. - Correct Answers -C, W, V, Kp(a),
Js(a), Lu(a), M
List several high incidence blood group antigens. - Correct Answers -Kp(b), k, Js(b),
Lu(b), I
Which RBC antigens are not fully expressed at birth? - Correct Answers -A, B, I, P₁,
Lewis, and Lutheran
What is an antibody? - Correct Answers -An immunoglobulin that is produced in
response to stimulation by a specific antigen and is capable of combining with the
antigen that elicited its production. Antibodies are also known as agglutinins. They are
found in the plasma and serum.
What is an alloantibody? - Correct Answers -An antibody to a foreign antigen from
someone from the same species.
What is an autoantibody? - Correct Answers -An antibody to an antigen that one
possesses. Autoantibodies are usually only produced in disease states.
What is a naturally-occurring antibody? - Correct Answers -One that develops without
known antigenic stimulus, for example, anti-A and anti-B.
What is an immune antibody? - Correct Answers -One that results from exposure to a
foreign red cell antigen through transfusion or pregnancy.
If an untransfused male has an unexpected alloantibody, what type of antibody must it
be? - Correct Answers -A naturally-occurring antibody. An untransfused male has not
been exposed to foreign RBC antigens.
What are high-titer, low-avidity blood group antibodies? - Correct Answers -Antibodies
that cause weak, variable, and sometimes irreproducible reactions in the antiglobulin
phase at high dilutions. They are not clinically significant. Examples include anti-Ch, Rg,
JMH, Cs<sup>a</sup>, Kn<sup>a</sup>, McC<sup>a</sup>, Yk<sup>a</sup>.
Which immunoglobulin molecules are most frequently encountered in blood banking? -
Correct Answers -IgM and IgG.
,Compare the molecular structure of IgG and IgM and explain how their structures
affects their reactivity in blood bank testing. - Correct Answers -IgG is a monomer.
Because of its small size, it usually cannot agglutinate saline suspended in RBCs. A
potentiating medium or antiglobulin test is required. IgM is a pentamer. Because of its
large size, it is a potent agglutinator, even of saline-suspended cells at room
temperature, and it is an efficient activator of complement.
Which class of immunoglobulins is destroyed by sulfhydryl compounds like 2-
mercaptoethanol or dithiothreitol? - Correct Answers -IgM. These compounds break the
J chains that hold IgM together.
Which immunoglobulin class is most efficient at activating complement? - Correct
Answers -IgM
Which immunoglobulin class can cross the placenta? - Correct Answers -IgG
What is sensitization? - Correct Answers -The attachment of antibodies to antigens on a
red cell.
List several factors that affect hemagglutination. - Correct Answers -The sensitization
phase is affected by the temperature, the pH, the ionic strength of the medium, the
antigen-antibody ratio, and the time of incubation. The agglutination phase is affected
by the type of the antibody, the density and the location of the antigens, and the zeta
potential (electrostatic repulsion).
What are some potentiators that are used to enhance antigen-antibody reactions? -
Correct Answers -22% albumin, low ionic strength salt solution (LISS), and polyethylene
glycol (PEG).
What is the advantage of using LISS? - Correct Answers -It increases the rate at which
an antibody binds to red cell antigens so the incubation time can be shortened to 10
minutes.
What are two visible signs of an antigen-antibody reaction in blood bank testing? -
Correct Answers -Agglutination and hemolysis.
What causes hemolysis? - Correct Answers -The complement terminal membrane
attack unit, C5b, C6, C7, C8, and C9. This unit embeds in the cell membrane and forms
a hole. The loss of membrane integrity and the change in osmotic pressure within the
cell leads to cell death and lysis.
Explain the correct way to examine a tube for signs of an antigen-antibody reaction. -
Correct Answers -Following centrifugation, the tube should be gently shaken or tilted
until the cell button is completely dispersed. The manner in which cells come off the
button should be observed. An optical aid, such as an agglutination viewer with a light
and a magnifying mirror, should be used.
, In tube testing, how would three large agglutinates against a clear background be
graded? - Correct Answers -3+
In blood bank records, what must be recorded in addition to the degree of reactivity in
all phases of testing? - Correct Answers -Interpretation of the reactions<br>Identity of
the person who performed the tests<br>Date of the testing<br>Timely supervisor review
is required.
Why should serum separator tubes not be used for blood bank testing? - Correct
Answers -The gel can contaminate the RBCs during sampling and cause false-positive
test results.
Name two new methods that are being used in blood bank testing. - Correct Answers -
Column (gel) technology and solid phase red cell adherence (SPRCA). Both of these
methods can be automated.
Explain the principle of gel technology. - Correct Answers -Rather than using traditional
test tubes, cards containing microtubes are used. Each microtube contains gel particles
and a reagent specific for the test being performed. Following addition of serum or cells,
the cards are incubated and centrifuged. If agglutination has occurred, the agglutination
complexes are trapped in the gel; non-agglutinated cells settle to the bottom of the
microtube. Reactions are scored from 0-4+ depending on the disbursement of the red
cells in the microtube.
A gel microtube shows a well-delineated pellet at the bottom following incubation and
centrifugation. How should this reaction be graded? - Correct Answers -Negative.
A gel microtube shows a solid band of red cell agglutinates on the top of the gel
following incubation and centrifugation. How should this reaction be graded? - Correct
Answers -4+
What does a mixed field reaction look like in a gel? - Correct Answers -A band of red
cell agglutinates on top of the gel and a pellet of unagglutinated cells at the bottom of
the microtube.
What are the advantages of gel technology? - Correct Answers -Better standardization,
increased sensitivity, and clearer end-points. Tube shaking, cell washing, red cell
resuspension, and antiglobulin controls are not required. Reactions are stable for 24
hours. Gel technology can now be automated. Gels are available for antigen typing,
antibody detection and identification, and crossmatching.
Explain how antibodies are identified by solid phase adherence. - Correct Answers -The
patient's serum is added to microplate wells that are coated with a monolayer of reagent
blood cells. During incubation, if antibodies are present in the serum they will attach to
the corresponding antigens on the sides of the wells. The microplate is washed to
