ABO Blood Group System_Harr Flashcards
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
An A2 person may form anti-A1; an A1 person will not form anti-A1
The group A1 comprises both A1 and A antigens.
Anti-A will react with both A1- and A2-positive RBCs.
A person who is group A2 may form anti-A1, but an
A1 person will not form anti-A1 (which would cause
autoagglutination).
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
The patient may be a Bombay
Bombay is the only ABO phenotype incompatible with O cells. The red cells of a Bombay show a negative reaction to anti-H because the cells contain
no H substance.
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
Anti-A, B, and H
A Bombay individual does not express A, B, or H
antigens; therefore anti-A, B, and H are formed.
Because a Bombay individual has three antibodies,
the only compatible blood must be from another
Bombay donor
Acquired B antigens have been found in:
A. Bombay individuals
B. Group O persons
C. All blood groups
D. Group A persons
Group A persons
The acquired B phenomenon is only seen in group A
persons.
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
The patient is an A2 with anti-A1
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.
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 room temperature 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
Incubate washed red cells with anti-A1 and
anti-A,B for 30 minutes at room temperature
The strong 4+ reaction in reverse grouping suggests
the discrepancy is in forward grouping. Incubating
washed red cells at room temperature with anti-A
and anti-A,B will enhance reactions.
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
Anti-A 4+, anti-B 1+, A1 cells neg, B cells 4+
In forward typing, a 1+ reaction with anti-B is suspicious because of the weak reaction and the normal reverse grouping that appears to be group A.
This may be indicative of an acquired antigen. In the
case of an acquired B, the reverse grouping is the same for a group A person. Choice A is indicative of
group AB; choice B is indicative of a group A who may be immunocompromised. Choice D may be
caused by a mistyping or an antibody against
antigens on reverse cells.
Which blood group has the least amount of H antigen?
A. A1B
B. A2
C. B
D. A1
A1B
The A1B blood group has the least amount of H antigen. This is due to both A and B epitopes present on red cells compromising the availability of H epitopes. A1B cells will yield weak reactions with
anti-H lectin
What type RBCs can be transfused to an A2 person with anti-A1?
A. A only
B. A or O
C. B
D. AB
A or O
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 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
Wash the cells with warm saline, autoadsorb the
serum at 4°C
These results point to a cold autoantibody. Washing the cells with warm saline may elute the autoantibody, allowing a valid forward type to be
performed. The serum should be adsorbed using
washed cells until the autocontrol is negative. Then
the adsorbed serum should be used for reverse
typing.
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
Incubate at 22°C or 4°C to enhance weak
expression
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.
N-acetyl-D-galactosamine is the immunodominant
carbohydrate that reacts with:
A. Arachis hypogaea
B. Salvia sclarea
C. Dolichos biflorus
D. Ulex europeaus
Dolichos biflorus
The immunodominant sugar N-acetyl-galactosamine
confers A antigen specificity when present at the
terminus of the type 2 precursor chain on the RBC
membrane. Therefore, its presence would cause RBCs to react with anti-A1 lectin, Dolichos biflorus.
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
Immunodeficiency
A transplant patient is probably taking immunosuppressive medication to increase graft
survival. This can contribute to the loss of normal
blood group antibodies as well as other types of
antibodies.
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
Equal reaction with anti-H
Anti-A,B should react positively with group A or B and
any subgroup of A or B (with exception of Am). An A1
(not A2) would react with anti-A1 lectin; only an A2
person with anti-A1 would give a positive reaction
with A1 cells; an A2 would react more strongly with
anti-H than A1
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
Alloantibody in patient serum
The patient is most likely an AB person who has
formed a cold-reacting alloantibody reacting with
B cells and O cells. An identification panel should be
performed. An acquired B person or someone with
hypogammaglobulinemia should not make antibody
that would agglutinate O cells.
