Transfusion Medicine Study Material for CSMLS || with
Error-free Solutions.
What would be the laboratory findings in a patient with a partial D phenotype? correct answers
Patient cells will react weakly to reagent anti-D antibody
What is the pathogenesis of alloanti-D antibodies in patients with a partial D phenotype? correct
answers Patients lack certain antigenic components on their own D antigens, so they make anti-D
to any red cells that express the full D protein.
Give some reasons why a patient that expresses an Rh D phenotype may be found to have anti-D
on screening. correct answers - Clerical error
- Partial D RBC phenotype
- Passive acquisition of anti-D from a red cell transfusion
- Autoagglutinins
What are the two most common causes of anti-D alloantibody? correct answers
Alloimmunization through:
- Transfusion or
- Pregnancy
What percentage of D-negative patients will develop anti-D antibody if transfused with D
antigen positive red cells? correct answers ~80%
How much plasma is included in a unit of packed red cells that is preserved with CPDA? correct
answers In CPDA units: 50 mL
What is the frequency of the k antigen in the donor population? correct answers - 98.8%
- This means that, if a k− patient needs a transfusion because they have an anti-k antibody, only
0.2% of donors will be compatible with this patient
Are anti-M antibodies IgG or IgM? Are they normally clinically significant? correct answers -
Anti-M tends to be IgG
- Even though they are IgG, they are most often cold reactive antibodies and are therefore
clinically insignificant
What is the Cobalt (Co) antigen? correct answers It is found on the plasma membrane of red
blood cells and renal tubular epithelial cells. It is on a protein called aquaporin-1 (AQP1 gene
product), which is responsible for water homeostasis and urine concentration.
How frequent is the Co(a) antigen in the donor population? correct answers - Found in 99.8% of
donors
- Thus finding Co(b) or Co-null blood is very difficult
,Are anti-Co(a) antibodies IgG or IgM? Are they normally clinically significant? correct answers
- Usually IgG antibodies
- Can cause hemolytic transfusion reaction and HDFN
A post-transfusion blood sample has a positive DAT. What is the next appropriate procedure?
correct answers An elution test should be performed to find the antibody specificity.
Possible reasons for a panreactive antibody on DAT. correct answers - Warm autoantibody
- An antibody to a high incidence antigen
Is a DAT-positive donor unit likely to have clinically significant antibodies? correct answers No,
because the antibodies bound to the donor red cells will stay bound in vivo in the recipient.
The reactivity of blood group A is confirmed by detecting the presence of which
immunodominant sugar molecule? correct answers The A gene codes for production of N-
acetylgalactosamine transferase, an enzyme which binds N-acetylgalactosamine (GalNAc) to the
H structure (L-fucose).
A mnemonic for remembering that the carbohydrate in blood group A is N-acetylgalactosamine.
correct answers In my opinion, the best way to recognize the full sugar name is to remember the
abbreviation. GalNAc would likely point you towards something containing a "...gal..." in the
answer. -bbguy.org
Why do individuals with the Bombay phenotype (O(h)) lack alloanti-O antibodies? correct
answers "O, please remember, is not an antigen, it's the lack of A and B antigens, so anti-O is not
a legitimate antibody." -bbguy.org
Which cells agglutinate most strongly with Ulex europaeus lectin? correct answers This
particular lectin, when tested against human red cells, closely parallels the reactivity we'd expect
to see if we used actual anti-H. The main blood groups agglutinate with the following relative
strength with anti-H or Ulex lectin: *O > A₂ > B > A₂B > A₁ > A₁B*. Cells of Group O and A₂
not only have the most H antigen of all the groups, but also have a molecular structure that
leaves fucose very accessible to anti-H. As a result, these cells agglutinate very strongly with
Ulex.
What are some characteristics of naturally occurring (non-alloimmune) antibodies that
distinguishes them from alloimmune (transfusion-related) antibodies? correct answers In short,
naturally occurring antibodies are generally of the IgM class, not able to cross the placenta,
enhanced in reactivity by incubation at 4C, and cause direct agglutination at room temperature.
ABOMNILS are red cell stimulated (not naturally occurring)
What ABH substances would be found in the saliva of a group B secretor? correct answers H and
B. The secretor status of an individual (genotype SeSe or Sese) determines the formation of H
antigen in secretions, which in turn creates opportunity for A and B antigen formation, if either
(or both) gene is inherited
, Can an individual of a secretor phenotype (genotype of SeSe or Sese) have O antigen in their
secretions? correct answers No. There is no such thing as O antigen!
The ABO system is the most important blood group system in transfusion safety. Why? correct
answers ABO is the only blood group system in which reciprocal antibodies are normally
produced for the antigens an individual lacks AND the ABO antibodies are capable of causing
rapid, intravascular hemolysis.
An ABO discrepancy between forward and reverse grouping owing to weak-reacting or missing
antibodies could be BEST explained by _____. correct answers Patients with extreme ages (the
very old or the very young). In the very old and very young, the natural expression of
isoagglutinins can either be depressed or delayed, respectively
What could be the cause of a missing red cell (forward) reaction type of ABO incompatibility?
correct answers Group A subgroups often lead to missing red cell (forward) reactions
What could be the cause of an ABO discrepancy that results in an extra red cell (forward typing)
reaction? correct answers Acquired B phenomenon results in extra red cell reactions
A blood donor has the genotype hh, AB. What is his apparent red cell phenotype during routine
forward and reverse group typing? correct answers Type O. Without either the HH or Hh
genotype, and the resulting "H Structure," the A and B antigens inherited as part of the AB
genotype are unable to attach to the RBC membrane type 2 chains. Such an individual's red cells
would appear as group O, phenotypically.
Approximately what percentage of group A individuals could be further classified as subgroup
A₁? correct answers About 80%
Lectin that agglutinates type A₁ but not A₂ RBCs correct answers Dolichos biflorus
Patients with A₂ phenotype can produce naturally occurring (ie, immune) anti-A₁ antibodies.
What is the clinical significance of these antibodies? correct answers Anti-A₁ is almost
invariably clinically insignificant
Which genes codes for production of the same basic antigen as the H gene? correct answers
Secretor (Se) gene
Color of anti-B reagent antibody correct answers Yellow
Color of anti-A reagent anti-body correct answers Blue
Which reagent antibody is in this bottle? correct answers Anti-B
Which reagent antibody is in this bottle? correct answers Anti-A
Error-free Solutions.
What would be the laboratory findings in a patient with a partial D phenotype? correct answers
Patient cells will react weakly to reagent anti-D antibody
What is the pathogenesis of alloanti-D antibodies in patients with a partial D phenotype? correct
answers Patients lack certain antigenic components on their own D antigens, so they make anti-D
to any red cells that express the full D protein.
Give some reasons why a patient that expresses an Rh D phenotype may be found to have anti-D
on screening. correct answers - Clerical error
- Partial D RBC phenotype
- Passive acquisition of anti-D from a red cell transfusion
- Autoagglutinins
What are the two most common causes of anti-D alloantibody? correct answers
Alloimmunization through:
- Transfusion or
- Pregnancy
What percentage of D-negative patients will develop anti-D antibody if transfused with D
antigen positive red cells? correct answers ~80%
How much plasma is included in a unit of packed red cells that is preserved with CPDA? correct
answers In CPDA units: 50 mL
What is the frequency of the k antigen in the donor population? correct answers - 98.8%
- This means that, if a k− patient needs a transfusion because they have an anti-k antibody, only
0.2% of donors will be compatible with this patient
Are anti-M antibodies IgG or IgM? Are they normally clinically significant? correct answers -
Anti-M tends to be IgG
- Even though they are IgG, they are most often cold reactive antibodies and are therefore
clinically insignificant
What is the Cobalt (Co) antigen? correct answers It is found on the plasma membrane of red
blood cells and renal tubular epithelial cells. It is on a protein called aquaporin-1 (AQP1 gene
product), which is responsible for water homeostasis and urine concentration.
How frequent is the Co(a) antigen in the donor population? correct answers - Found in 99.8% of
donors
- Thus finding Co(b) or Co-null blood is very difficult
,Are anti-Co(a) antibodies IgG or IgM? Are they normally clinically significant? correct answers
- Usually IgG antibodies
- Can cause hemolytic transfusion reaction and HDFN
A post-transfusion blood sample has a positive DAT. What is the next appropriate procedure?
correct answers An elution test should be performed to find the antibody specificity.
Possible reasons for a panreactive antibody on DAT. correct answers - Warm autoantibody
- An antibody to a high incidence antigen
Is a DAT-positive donor unit likely to have clinically significant antibodies? correct answers No,
because the antibodies bound to the donor red cells will stay bound in vivo in the recipient.
The reactivity of blood group A is confirmed by detecting the presence of which
immunodominant sugar molecule? correct answers The A gene codes for production of N-
acetylgalactosamine transferase, an enzyme which binds N-acetylgalactosamine (GalNAc) to the
H structure (L-fucose).
A mnemonic for remembering that the carbohydrate in blood group A is N-acetylgalactosamine.
correct answers In my opinion, the best way to recognize the full sugar name is to remember the
abbreviation. GalNAc would likely point you towards something containing a "...gal..." in the
answer. -bbguy.org
Why do individuals with the Bombay phenotype (O(h)) lack alloanti-O antibodies? correct
answers "O, please remember, is not an antigen, it's the lack of A and B antigens, so anti-O is not
a legitimate antibody." -bbguy.org
Which cells agglutinate most strongly with Ulex europaeus lectin? correct answers This
particular lectin, when tested against human red cells, closely parallels the reactivity we'd expect
to see if we used actual anti-H. The main blood groups agglutinate with the following relative
strength with anti-H or Ulex lectin: *O > A₂ > B > A₂B > A₁ > A₁B*. Cells of Group O and A₂
not only have the most H antigen of all the groups, but also have a molecular structure that
leaves fucose very accessible to anti-H. As a result, these cells agglutinate very strongly with
Ulex.
What are some characteristics of naturally occurring (non-alloimmune) antibodies that
distinguishes them from alloimmune (transfusion-related) antibodies? correct answers In short,
naturally occurring antibodies are generally of the IgM class, not able to cross the placenta,
enhanced in reactivity by incubation at 4C, and cause direct agglutination at room temperature.
ABOMNILS are red cell stimulated (not naturally occurring)
What ABH substances would be found in the saliva of a group B secretor? correct answers H and
B. The secretor status of an individual (genotype SeSe or Sese) determines the formation of H
antigen in secretions, which in turn creates opportunity for A and B antigen formation, if either
(or both) gene is inherited
, Can an individual of a secretor phenotype (genotype of SeSe or Sese) have O antigen in their
secretions? correct answers No. There is no such thing as O antigen!
The ABO system is the most important blood group system in transfusion safety. Why? correct
answers ABO is the only blood group system in which reciprocal antibodies are normally
produced for the antigens an individual lacks AND the ABO antibodies are capable of causing
rapid, intravascular hemolysis.
An ABO discrepancy between forward and reverse grouping owing to weak-reacting or missing
antibodies could be BEST explained by _____. correct answers Patients with extreme ages (the
very old or the very young). In the very old and very young, the natural expression of
isoagglutinins can either be depressed or delayed, respectively
What could be the cause of a missing red cell (forward) reaction type of ABO incompatibility?
correct answers Group A subgroups often lead to missing red cell (forward) reactions
What could be the cause of an ABO discrepancy that results in an extra red cell (forward typing)
reaction? correct answers Acquired B phenomenon results in extra red cell reactions
A blood donor has the genotype hh, AB. What is his apparent red cell phenotype during routine
forward and reverse group typing? correct answers Type O. Without either the HH or Hh
genotype, and the resulting "H Structure," the A and B antigens inherited as part of the AB
genotype are unable to attach to the RBC membrane type 2 chains. Such an individual's red cells
would appear as group O, phenotypically.
Approximately what percentage of group A individuals could be further classified as subgroup
A₁? correct answers About 80%
Lectin that agglutinates type A₁ but not A₂ RBCs correct answers Dolichos biflorus
Patients with A₂ phenotype can produce naturally occurring (ie, immune) anti-A₁ antibodies.
What is the clinical significance of these antibodies? correct answers Anti-A₁ is almost
invariably clinically insignificant
Which genes codes for production of the same basic antigen as the H gene? correct answers
Secretor (Se) gene
Color of anti-B reagent antibody correct answers Yellow
Color of anti-A reagent anti-body correct answers Blue
Which reagent antibody is in this bottle? correct answers Anti-B
Which reagent antibody is in this bottle? correct answers Anti-A
