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Immunohematology Questions and Answers
*Meiosis in cell division is limited to the ova and
sperm producing four gametes containing what
complement of DNA?
A. 1N
B. 2N
C. 3N
D. 4N Ans: A. Meiosis involves two nuclear divisions in
succession resulting in four gametocytes each containing half the
number of chromosomes found in somatic cells or 1N.
*The alleged father of a child in a disputed case of paternity is
blood group AB. The mother is group O and the child is group O.
What type of exclusion is this?
A. Direct/primary/first order
B. Probability
C. Random
D. Indirect/secondary/second order Ans: D. An
indirect/secondary/second order exclusion occurs when a genetic
marker is absent in the child but should have been transmitted by
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the alleged father. In this case, either A or B should be present in
the child.
*Blood is crossmatched on an A positive person with
a negative antibody screen. The patient received a
transfusion of A positive RBCs 3 years ago. The
donors chosen for crossmatch were A positive.
The crossmatch was run on the Ortho Provue and
yielded 3+ incompatibility. How can these results
be explained?
A. The patient has an antibody to a low-frequency
antigen
B. The patient has an antibody to a high-frequency
antigen
C. The patient is an A2 with anti-A1
D. The patient is an A1 with anti-A2 Ans: C. The patient is likely
an A2 with anti-A1 which is
causing reactivity in the crossmatch. A negative
antibody screen rules out the possibility of an
antibody to a high-frequency antigen, and two
donor units incompatible rules out an antibody to
a low-frequency antigen.
*What type RBCs can be transfused to an A2 person
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with anti-A1?
A. A only
B. A or O
C. B
D. AB Ans: B. A person in need of an RBC transfusion who is an
A2 with anti-A1 can be transfused A or O cells because the anti-A1
is typically only reactive at room
temperature.
*What should be done if all forward and reverse
ABO results are negative?
A. Perform additional testing such as typing with
anti-A1 lectin and anti-A,B
B. Incubate at 22°C or 4°C to enhance weak
expression
C. Repeat the test with new reagents
D. Run an antibody identification panel Ans: B. All negative
results may be due to weakened
antigens or antibodies. Room temperature or lower
incubation temperature may enhance expression of
weakened antigens or antibodies.
*Which condition would most likely be responsible
for the following typing results?
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Patient cells: Anti-A, neg Anti-B, neg
Patient serum: A1 cells, neg B cells, 4+
A. Immunodeficiency
B. Masking of antigens by the presence of massive
amounts of antibody
C. Weak or excessive antigen(s)
D. Impossible to determine Ans: C. Excessive A substance, such
as may be found in some types of tumors, may be neutralizing the
anti-A. Weak A subgroups may fail to react with anti-A and require
additional testing techniques (e.g., room-temperature incubation)
before their expression is apparent.
*A 61-year-old male with a history of multiple
myeloma had a stem cell transplant 3 years ago.
The donor was O positive and the recipient was
B positive. He is admitted to a community
hospital for fatigue and nausea. Typing results
reveal the following:
Anti-A = 0
Anti-B =0
Anti-A,B = 0
Anti-D = 4+
A1 cells = 4+
B cells = 0
© 2025 All rights reserved
Immunohematology Questions and Answers
*Meiosis in cell division is limited to the ova and
sperm producing four gametes containing what
complement of DNA?
A. 1N
B. 2N
C. 3N
D. 4N Ans: A. Meiosis involves two nuclear divisions in
succession resulting in four gametocytes each containing half the
number of chromosomes found in somatic cells or 1N.
*The alleged father of a child in a disputed case of paternity is
blood group AB. The mother is group O and the child is group O.
What type of exclusion is this?
A. Direct/primary/first order
B. Probability
C. Random
D. Indirect/secondary/second order Ans: D. An
indirect/secondary/second order exclusion occurs when a genetic
marker is absent in the child but should have been transmitted by
© 2025 All rights reserved
, 2 | Page
the alleged father. In this case, either A or B should be present in
the child.
*Blood is crossmatched on an A positive person with
a negative antibody screen. The patient received a
transfusion of A positive RBCs 3 years ago. The
donors chosen for crossmatch were A positive.
The crossmatch was run on the Ortho Provue and
yielded 3+ incompatibility. How can these results
be explained?
A. The patient has an antibody to a low-frequency
antigen
B. The patient has an antibody to a high-frequency
antigen
C. The patient is an A2 with anti-A1
D. The patient is an A1 with anti-A2 Ans: C. The patient is likely
an A2 with anti-A1 which is
causing reactivity in the crossmatch. A negative
antibody screen rules out the possibility of an
antibody to a high-frequency antigen, and two
donor units incompatible rules out an antibody to
a low-frequency antigen.
*What type RBCs can be transfused to an A2 person
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with anti-A1?
A. A only
B. A or O
C. B
D. AB Ans: B. A person in need of an RBC transfusion who is an
A2 with anti-A1 can be transfused A or O cells because the anti-A1
is typically only reactive at room
temperature.
*What should be done if all forward and reverse
ABO results are negative?
A. Perform additional testing such as typing with
anti-A1 lectin and anti-A,B
B. Incubate at 22°C or 4°C to enhance weak
expression
C. Repeat the test with new reagents
D. Run an antibody identification panel Ans: B. All negative
results may be due to weakened
antigens or antibodies. Room temperature or lower
incubation temperature may enhance expression of
weakened antigens or antibodies.
*Which condition would most likely be responsible
for the following typing results?
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, 4 | Page
Patient cells: Anti-A, neg Anti-B, neg
Patient serum: A1 cells, neg B cells, 4+
A. Immunodeficiency
B. Masking of antigens by the presence of massive
amounts of antibody
C. Weak or excessive antigen(s)
D. Impossible to determine Ans: C. Excessive A substance, such
as may be found in some types of tumors, may be neutralizing the
anti-A. Weak A subgroups may fail to react with anti-A and require
additional testing techniques (e.g., room-temperature incubation)
before their expression is apparent.
*A 61-year-old male with a history of multiple
myeloma had a stem cell transplant 3 years ago.
The donor was O positive and the recipient was
B positive. He is admitted to a community
hospital for fatigue and nausea. Typing results
reveal the following:
Anti-A = 0
Anti-B =0
Anti-A,B = 0
Anti-D = 4+
A1 cells = 4+
B cells = 0
© 2025 All rights reserved
