Deck 10: Detection and Identification of Antibodies

Question 1

Why is it important to match the lot number on the panel sheet with the lot number on the panel cells?

A) The ABO group will change from lot to lot.
B) Pattern of reactions will change from lot to lot.
C) It is a requirement of the FDA.
D) All of the above

Answer 1

B

Question 2

How does LISS enhance antibody detection in the antibody screen?

A) Increases the incubation times, which increases the sensitivity of the test
B) Increases the zeta potential, promoting agglutination of sensitized red blood cells
C) Increases the rate at which antibody binds to red blood cell antigens
D) None of the above

Answer 2

C

Question 3

What is an elution?

A) A technique used to dissociate IgM antibodies from sensitized RBCs
B) A technique used to dissociate IgG antibodies from sensitized RBCs
C) A technique used to reduce the zeta potential enhancing antigen binding
D) None of the above

Answer 3

B

Question 4

A positive autocontrol in antibody detection procedures is usually indicative of:

A) inadequate washing.
B) positive DAT.
C) positive IAT.
D) none of the above.

Question 5

Which cells are employed to remove autoantibody from patient serum without removing any alloantibody from serum?

A) Coombs' control red blood cells
B) Screening red blood cells
C) Patient red blood cells
D) Panel red blood cells

Question 6

Why is an enzyme treatment used in antibody identification?

A) Enzymes aid in the dissociation of antibody from antigen in a positive DAT.
B) Enzymes aid in the separation and identification of multiple antibodies.
C) Enzymes aid in the absorption of autoantibody from patient serum.
D) Enzymes aid in the separation and identification of multiple antibodies and the absorption of autoantibody from patient serum.

Question 7

Which of the following high-frequency antigens do not cause in vivo red blood cell destruction when complexed with corresponding antibody?

A) k
B) Js^b
C) Ch^a
D) Lu^b

Question 8

Which of the following is a mechanism of an elution procedure?

A) Disruption of structural complementarity of antigen and antibody
B) Enhancement of structural complementarity of antigen and antibody
C) Exchange of one immunoglobulin class for another
D) Denaturation of membrane epitopes by chemical means

Question 9

A patient with a warm autoantibody has a positive DAT. The antibody screen was negative, but the eluate reacted uniformly with all normal cells and patient cells. Why was the antibody screen negative?

A) Reagent red blood cells were saturated with warm autoantibody from patient serum.
B) No alloantibodies were present.
C) The warm autoantibody has bound to patient RBCs in circulation.
D) Polyspecific AHG was used instead of monospecific IgG.

Question 10

What screening cells are used primarily for testing donor units for unexpected antibodies?

A) Pooled
B) 2-vial
C) 3-vial
D) 4-vial

Question 11

When performing the elution procedure, the solution containing the recovered antibody is called:

A) neutralized serum.
B) the buffer.
C) the eluate.
D) absorbed serum.

Question 12

The process of removing antibody from serum by combining a serum sample with appropriate red blood cells under optimal conditions is called:

A) elution.
B) absorption.
C) enzyme treatment.
D) sensitization.

Question 13

Which of the following statements concerning acid eluates is false?

A) Citric acid is an example of an acid eluate.
B) The pH is reduced to 3 or less to disrupt the antigen-antibody complex.
C) The pH of the eluate remains at 3 before testing against a panel.
D) None of the above

Question 14

What is the purpose of Coombs' control cells?

A) To ensure that AHG tests with negative results are not false-negatives
B) To ensure that washing removed all unbound antibody
C) To ensure that AHG was not omitted or inactivated
D) All of the above

Question 15

Routine pretransfusion testing consists of all of the following except:

A) ABO typing.
B) Rh typing.
C) an antibody screen.
D) a DAT.

Question 16

What would be a realistic source of finding compatible units for a person with an antibody to a high-frequency antigen?

A) Random donor units
B) A donor of similar ethnic background
C) Siblings
D) Apheresis donors

Question 17

In what test might rouleaux cause an interference?

A) DAT
B) Forward ABO grouping
C) Reverse ABO grouping
D) Rh control

Question 18

In interpreting an antibody screen, which of the following questions might be asked to decipher the class of antibody?

A) Is the autologous control positive or negative?
B) Is hemolysis present?
C) In what phase did the reaction occur?
D) Is rouleaux present?

Question 19

Which of the following statements is correct concerning cold antibody screens?

A) Patient serum is incubated with group O adult and cord red blood cells at 4°C.
B) Patient serum is incubated with group O cord cells at 37°C.
C) Patient serum is incubated with check cells at 18°C.
D) Patient serum is incubated with group A cord cells at room temperature.

Question 20

A person has developed an antibody to the LISS reagent. What test will not be affected by this circumstance?

A) Major ACT crossmatch
B) IAT
C) DAT
D) Antibody screen

Question 21

Why are screening cells group O?

A) To prevent interference with anti-A and anti-B in patient serum
B) To prevent interference with A and B antigens on patient cells
C) Because group O cells are easier to acquire in random populations
D) Because group O cells contain antigens to clinically significant antibodies

Question 22

What determines if a red blood cell antibody is clinically significant?

A) Class of antibody (IgG or IgM)
B) Shortened red blood cell survival
C) Shortened white blood cell survival
D) Shortened platelet survival

Question 23

Why is rouleaux not usually found in the AHG phase of antibody screens?

A) High protein molecules are not reactive at 37°C.
B) Patient cells are washed away before adding AHG.
C) Patient serum is washed away before adding AHG.
D) None of the above

Question 24

Cold-reactive autoantibodies can be selectively removed from patient serum by adsorption with autologous red blood cells (RBCs). What other cells can be used?

A) Mouse RBCs
B) Goat RBCs
C) Rabbit RBCs
D) Donor RBCs

Question 25

What is tested in an antibody screen?

A) Patient red blood cells are tested against group O reagent screening cells.
B) Patient serum is tested against group AB reagent screening cells.
C) Patient serum is tested against group O reagent screening cells.
D) Patient serum is tested against group A reagent screening cells.

Question 26

What test is used to confirm the efficacy of chloroquine treatment?

A) IAT
B) DAT
C) ABO grouping
D) Neutralization test

Question 27

In what circumstance would an alloadsorption be performed?

A) Warm autoantibody in serum
B) HDN
C) Multiple antibodies in serum
D) Hemolytic transfusion reaction

Question 28

Neutralization of antibody is applicable to all of the following blood groups except:

A) Lewis.
B) Rh.
C) P₁.
D) Chido.

Question 29

What might a positive antibody screen and a negative auto control indicate?

A) An alloantibody is coating donor cells after a transfusion
B) An autoantibody has been detected
C) An alloantibody has been detected
D) Drug-induced antibody reacting with patient cells

Question 30

What is a positive DAT?

A) In vitro sensitization of RBC with antigen
B) In vitro sensitization of RBC with antibody
C) In vivo sensitization of RBC with antibody
D) In vivo sensitization of RBC with antigen

Question 31

Why are antibodies to high-frequency antigens, such as cellano (k), rarely seen in patient samples?

A) Most persons are not antigenically stimulated to produce the antibody, because their red blood cells are negative for the antigen.
B) Most persons are not antigenically stimulated to produce the antibody, because their red blood cells are positive for the antigen.
C) Anti-k has low avidity.
D) Most reagent cells are heterozygous for cellano.

Question 32

What antibody is associated with a mixed-field reaction?

A) Le^a
B) K
C) Sd^a
D) E

Question 33

What can be concluded in a patient who has anti-K identified in his serum but phenotypes positive for K antigen?

A) Kell antiserum was omitted.
B) Patient was recently transfused with K-positive blood.
C) Anti-K was misidentified
D) Patient was recently transfused with K-positive blood and Anti-K was misidentified

Question 34

How is an antibody ruled in?

A) Two RBC samples positive for antigen show reactivity; two RBC samples negative for the antigen show no reactivity.
B) Three RBC samples positive for antigen show reactivity; three RBC samples negative for the antigen show no reactivity.
C) One homozygous RBC sample shows reactivity.
D) None of the above

Question 35

When might you suspect multiple antibodies in a patient's serum?

A) Pattern of reactivity not fitting a single antibody
B) Variation in phase of reactivity
C) Variation in antibody reactivity strength
D) All of the above

Question 36

What effect does ZZAP reagent have on sensitized red blood cells?

A) Removes antibody from red blood cells
B) Enzyme treats red blood cells
C) Increases adsorption capability of red blood cells
D) All of the above

Question 37

What is a possible explanation for a nonreactive eluate?

A) Hemolytic disease of the newborn (HDN)
B) Positive DAT due to drugs
C) A warm autoantibody
D) All of the above

Question 38

What is the most common use of adsorption?

A) Removal of plasma protein from patient serum
B) Removal of alloantibody from patient serum
C) Removal of autoantibody from patient serum
D) Removal of drug-induced antibody from patient serum

Question 39

Which is the second phase of a hemagglutination reaction?

A) Immunodiffusion
B) Precipitation
C) Sensitization
D) Agglutination

Question 40

Why is it important for screening cells to be from individuals who have a homozygous expression of antigens?

A) Homozygous expression is directly related to clinically significant antibodies.
B) Stronger reactions are seen with heterozygous cells than with homozygous cells.
C) Weakly reacting antibodies may not agglutinate heterozygous cells.
D) All of the above

Question 41

Why might some blood banking facilities prefer the use of monospecific IgG over polyspecifiic antihuman globulin (AHG) in their antibody screens?

A) Interference from naturally occurring warm antibodies in patient serum is reduced.
B) Interference from naturally occurring cold antibodies in patient serum is reduced.
C) There is more IgG in monospecific antisera than in polyspecific reagents.
D) Monospecific IgG has been standardized.

Question 42

Why should only homozygous cells be used to rule out an antibody?

A) Homozygous cells carry a double dose of antibody.
B) Weakly reacting antibody may not react with heterozygous cells.
C) Strong reacting antibodies may not react with heterozygous cells.
D) All of the above

Question 43

What is the purpose of saline washing in the antibody screen procedure?

A) Removal of bound IgG that would otherwise neutralize the AHG reagent
B) Removal of unbound IgG that would neutralize the AHG reagent
C) Stripping of the red blood cell membrane for alloantibody binding
D) Removal of unbound IgM that would neutralize AHG reagent

Question 44

What is an antigen profile sheet?

A) An insert listing the antibodies present in each vial of screening cells
B) An insert listing the antigenic makeup of each vial of screening cells
C) A statistical comparison of 200 blood banks' results of antigenic reactions with various antisera
D) An insert listing the antigenic makeup of check cells

Question 45

What is the first step in reading hemagglutination reactions?

A) Resuspension of red blood cells
B) Checking supernatant for hemolysis
C) Grading agglutination
D) None of the above

Question 46

Tests with which AHG reagents can determine if IgG, complement, or both are coating red blood cells?

A) Monospecific
B) Polyspecific
C) Standardized
D) Irradiated

Question 47

A 2-unit crossmatch was ordered on a patient in the emergency room. The patient's antibody screen was negative. One unit was compatible and the other was incompatible at AHG. If the patient's antibody screen was negative and the donor had no history of antibodies, what could be the reason for this reaction?

A) The patient's serum has an antibody to a low-frequency antigen not present on screening cells.
B) The donor has a positive DAT.
C) The patient's serum has an HTLA antibody.
D) Options A and B

Question 48

During an antibody ID, there was 1+ reaction at AHG with donor cells with the antigen profile Fya(+), Fyb(-). All other donor cells on the panel were negative, including those that were Fya(+), Fyb(+). Given these results, what might be the conclusion?

A) Single antibody (showing dosage)
B) Probably an antibody not represented on the antigen profile
C) An antibody to a high-frequency antigen
D) IgM antibody

Question 49

What makes up an autologous control?

A) Patient serum and patient cells
B) Patient serum and screening cells
C) Patient cells and Rh control
D) None of the above

Question 50

What is the purpose of treating serum containing cold autoantibodies with dithiothreitol (DTT) or 2-mercaptoethanol (2-ME)?

A) To denature IgG alloantibody and test serum for presence of IgM autoantibody
B) To denature IgM cold autoantibody and test serum for presence of IgM alloantibody
C) To denature IgM cold autoantibody and test serum for presence of IgG alloantibody
D) To denature IgM drug-induced antibody and test serum for presence of IgG alloantibody

Question 51

What test must be performed on a patient with a warm autoantibody in their serum before transfusing?

A) Prewarming
B) Warm autoadsorption
C) Elution
D) DAT

Question 52

Which of the following is known as the "sensitization phase" in the antibody screen?

A) Immediate spin
B) AHG
C) 37°C incubation
D) None of the above

Question 53

When should multiple antibodies be suspected in a positive antibody screen?

A) The autocontrol was positive.
B) Cells react at different phases and strengths.
C) Only the AHG phase is reactive.
D) None of the above

Question 54

What is the simplest way of reducing the interferences from benign cold autoantibodies in antibody screening procedures?

A) Use polyspecific AHG
B) Use monospecific IgG
C) Use prewarming techniques
D) Use cold autoabsorption techniques

Question 55

How many units would you likely have to screen to find two compatible units for someone with the following antibodies: anti-C, anti-Le^a, anti-Jk^b?

A) 10
B) 15
C) 32
D) 35

Question 56

When are antibody titration studies warranted?

A) During a gastrointestinal bleed
B) During pregnancy
C) After bone marrow transplantation
D) During chemotherapy

Question 57

How is chloroquine diphosphate used in blood banking?

A) To accurately phenotype patient cells when IAT is positive
B) To enhance antigen-antibody binding in IAT
C) To accurately phenotype patient cells when the DAT is positive
D) To be used as an Rh control when DAT is positive

Question 58

Why can't autoadsorption be performed on a patient who was transfused 1 month before?

A) Only IgM antibody would be present at 1 month.
B) Donor cells might adsorb out autoantibody in serum.
C) Patient cells might adsorb out alloantibody in serum.
D) Donor cells might adsorb out alloantibody in serum.

Question 59

In the autoabsorption procedure for the removal of cold autoagglutinins from serum, pretreatment of the patient's RBCs with which of the following reagents is helpful:

A) Ficin
B) Phosphate buffered saline
C) LISS
D) Albumin

Question 60

One drop of Coombs' control cells was added to a negative antibody screen. No agglutination was observed after centrifugation. What course of action is taken?

A) Report negative result
B) Report inconclusive result
C) Repeat the test
D) Add one more drop of check cells and re-centrifuge

Question 61

Pseudoagglutination:

A) is frequently associated with alterations in serum proteins.
B) occurs when serum viscosity is increased.
C) can be confused with panagglutination.
D) all of the above.

Question 62

How can neutralization aid in the identification of multiple antibodies?

A) Once antibody has been neutralized serum can be further tested in panel studies.
B) Neutralization inhibits all warm autoantibodies.
C) Neutralized serum can be used to phenotype patient cells.
D) All of the above

Question 63

A doctor has ordered 4 units of red blood cells for a patient with anti-E in his serum. How many units would have to be screened to yield 4 E-negative units?

A) 10
B) 15
C) 6
D) 12

Question 64

In which scenario can an antibody be ruled out?

A) Patient serum does not react with a cell known to carry the corresponding antigen.
B) Patient serum does react with a cell known to carry the corresponding antigen.
C) Patient cells do not react with a cell known to carry the corresponding antibody
D) Patient cells do react with a cell known to carry the corresponding antibody.

Question 65

What does a panel of reagent red blood cells consist of?

A) 1 to 5 group O red blood cell suspensions
B) 3-vial screening cells
C) 11 to 20 group O red blood cell suspensions
D) Pooled screening cells

Question 66

Antibodies resulting from exposure to pollen, fungus, or bacteria are known as:

A) active.
B) immune.
C) naturally occurring.
D) passive.

Question 67

Of the antibodies listed below, which does NOT fit with the others in terms of the optimal temperature of reactivity? Anti-P1
C) Anti-A1
Anti-I
D) Anti-E

Question 68

If you suspect anti-C is present in a patient's serum, and anti-Fy^a still has to be ruled out using other reagent cells, what would the phenotype of the rule out cell have to be?

A) Fy(a+), C-, Fy(b+)
B) Fy(a+), C-, Fy(b-)
C) Fy(a+), C+, Fy(b-)
D) Fy(a+), C+, Fy(b+)

Question 69

Name a disease in which your positive D control might be positive.

A) PCH
B) Multiple myeloma
C) Huntington's disease
D) Epstein-Barr virus

Question 70

Antibodies formed as the result of RBC stimulation in the patient are known as:

A) active.
B) immune.
C) naturally occurring.
D) passive.

Question 71

What is done with a patient's serum after an autoadsorption technique has been performed?

A) Alloantibodies are identified.
B) The serum is discarded.
C) Autoantibody is identified.
D) Alloantibodies are identified, and the serum can be used for compatibility testing.

Question 72

What is the advantage of having a 3-cell panel screen versus a 2-cell panel screen?

A) More cells in the homozygous state that show dosage
B) You can narrow down the specificity of the AB better.
C) You might detect more rare antibodies.
D) All of the above

Question 73

The AABB's Standards for Blood Banks and Transfusion Services requires antibody screen of all populations listed below EXCEPT:

A) allogeneic blood donors
B) patients receiving RBCs
C) patients receiving WBCs
D) prenatal patients

Question 74

Cells that have antibody attached to them but are still separated from one another are:

A) agglutinated.
B) sensitized.
C) phagocytized.
D) hemolyzed.

Question 75

What is the final step in antibody identification?

A) Phenotype donor's RBC units for corresponding antigen
B) Phenotype patient's RBCs for corresponding antibody
C) Phenotype patient's RBCs for corresponding antigen
D) Phenotype RBC units for corresponding antibody

Question 76

While performing an antibody screen, a test reaction is observed that is suspected to be rouleaux. A saline replacement test is done, and the reaction remains. What is the best interpretation?

A) The original reaction was rouleaux and may be ignored.
B) The replacement test is invalid and should be repeated.
C) The original reaction was due to true agglutination.
D) The antibody screen is negative.

Question 77

The electrical force that exists between red blood cells is:

A) called the zeta potential.
B) due to the net negative charge of the red blood cell membrane.
C) related to the voltage or potential that exists at the surface of the RBC and the outer layer of the ionic cloud.
D) all of the above.

Question 78

A laboratory employee who previously tested negative in a donor antibody screen is now testing positive after having had an intravenous immunoglobulin treatment for needle-stick exposure. Which type of antibody has this person formed?

A) active
B) immune
C) naturally occurring
D) passive