Immuhematology- ABO Blood Group System

Question 1

1. Which of the following distinguishes A1 from A2
   blood groups?
   A. A2 antigen will not react with anti-A, A1 will
   react strongly (4+)
   B. An A2 person may form anti-A1; an A1 person
   will not form anti-A1
   C. An A1 person may form anti-A2, an A2 person
   will not form anti-A1
   D. A2 antigen will not react with anti-A from a
   nonimmunized donor; A1 will react with any
   anti-A

Answer 1

B. An A2 person may form anti-A1; an A1 person
will not form anti-A1

Question 2

2. A patient’s serum is incompatible with O cells.
   The patient RBCs give a negative reaction to
   anti-H lectin. What is the most likely cause of
   these results?
   A. The patient may be a subgroup of A
   B. The patient may have an immunodeficiency
   C. The patient may be a Bombay
   D. The patient may have developed alloantibodies

Answer 2

C. The patient may be a Bombay

Question 3

3. What antibodies are formed by a Bombay
   individual?
   A. Anti-A and anti-B
   B. Anti-H
   C. Anti-A,B
   D. Anti-A, B, and H

Answer 3

D. Anti-A, B, and H

Question 4

4. Acquired B antigens have been found in:
   A. Bombay individuals
   B. Group O persons
   C. All blood groups
   D. Group A persons

Answer 4

D. Group A persons

Question 5

5. 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

Answer 5

C. The patient is an A2 with anti-A1

Question 6

6. A patient’s red cells forward as group O, serum
   agglutinates B cells (4+) only. Your next step
   would be:
   A. Extend reverse typing for 15 minutes
   B. Perform an antibody screen including a roomtemperature incubation
   C. Incubate washed red cells with anti-A1 and
   anti-A,B for 30 minutes at room temperature
   D. Test patient’s red cells with Dolichos biflorus

Answer 6

C. Incubate washed red cells with anti-A1 and
anti-A,B for 30 minutes at room temperature

Question 7

7. Which typing results are most likely to occur when
   a patient has an acquired B antigen?
   A. Anti-A 4+, anti-B-3+, A1 cells neg, B cells neg
   B. Anti-A 3+, anti-B neg, A1 cells neg, B cells neg
   C. Anti-A 4+, anti-B 1+, A1 cells neg, B cells 4+
   D. Anti-A 4+, anti-B 4+, A1 cells 2+, B cells neg

Answer 7

C. Anti-A 4+, anti-B 1+, A1 cells neg, B cells 4+

Question 8

8. Which blood group has the least amount of
   H antigen?
   A. A1B
   B. A2
   C. B
   D. A1

Answer 8

A. A1B

Question 9

9. What type RBCs can be transfused to an A2 person
   with anti-A1?
   A. A only
   B. A or O
   C. B
   D. AB

Answer 9

B. A or O

Question 10

10. What should be done if all forward and reverse
    ABO results as well as the autocontrol are positive?
    A. Wash the cells with warm saline, autoadsorb the
    serum at 4°C
    B. Retype the sample using a different lot number
    of reagents
    C. Use polyclonal typing reagents
    D. Report the sample as group AB

Answer 10

A. Wash the cells with warm saline, autoadsorb the
serum at 4°C

Question 11

11. 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

Answer 11

B. Incubate at 22°C or 4°C to enhance weak
expression

Question 12

12. N-acetyl-D-galactosamine is the immunodominant
    carbohydrate that reacts with:
    A. Arachis hypogaea
    B. Salvia sclarea
    C. Dolichos biflorus
    D. Ulex europeaus

Answer 12

C. Dolichos biflorus

Question 13

13. A stem cell transplant patient was retyped when
    she was transferred from another hospital. What is
    the most likely cause of the following results?

Patient cells:
- Anti-A, neg Anti-B, 4+
Patient serum:
- A1 cells, neg B cells, neg

A. Viral infection
B. Alloantibodies
C. Immunodeficiency
D. Autoimmune hemolytic anemia

Answer 13

C. Immunodeficiency

Question 14

14. What reaction would be the same for an A1 and an
    A2 person?
    A. Positive reaction with anti-A1 lectin
    B. Positive reaction with A1 cells
    C. Equal reaction with anti-H
    D. Positive reaction with anti-A,B

Answer 14

D. Positive reaction with anti-A,B

Question 15

15. A female patient at 28 weeks’ gestation yields the
    following results:

Patient cells:
- Anti-A, 3+ Anti-B, 4+
Patient serum:
- A1 cells, neg B cells, 1+ O cells, 1+

Which of the following could be causing the ABO
discrepancy?
A. Hypogammaglobulinemia
B. Alloantibody in patient serum
C. Acquired B
D. Weak subgroup

Answer 15

B. Alloantibody in patient serum

Question 16

16. Which condition would most likely be responsible
    for the following typing results?

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

Answer 16

C. Weak or excessive antigen(s)

Question 17

17. Which of the following results is most likely
    discrepant?
    Anti-A, neg Anti-B, 4+
    A1 cells, neg B cells, neg
    A. Negative B cells
    B. Positive reaction with anti-B
    C. Negative A1 cells
    D. No problem with this typing

Answer 17

C. Negative A1 cells

Question 18

18. 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

How would you report this type?
A. O positive
B. B positive
C. A positive
D. Undetermined

Answer 18

D. Undetermined