Question 1

In the process of identifying an antibody,the technologist observed 2+ reactions with 3 of the 10 cells in a panel at the immediate-spin phase.These reactions disappeared following incubation at 37° C and the antihuman globulin phase of testing.What is the most likely responsible antibody? A) Anti-E B) Anti-D C) Anti-I D) Anti-Le^a

Accepted Answer

The Le? antigen is typically found on three to four cells in a panel,and the antibody reacts best at the immediate-spin phase of testing.

Question 2

Which of the following antigens is not commonly used on screening cells? A) D B) k C) Kp^a D) C

Accepted Answer

Kp? is a low-frequency antigen in the Kell system that is typically not present on screening cells.

Question 3

Why are proteolytic enzymes not used in the routine screening for antibodies?
A) The reagent is too expensive for routine use.
B) Clinically insignificant antibodies are enhanced.
C) Red cells must be treated with enzymes first, which makes this technique impractical.
D) Some antigens are destroyed by enzymes, which would cause the antibodies to be missed.

Accepted Answer

Proteolytic enzymes destroy some antigens in the Duffy and MNS system.Antibody screens using enzymes would not detect antibodies to these antigens.

Question 4

If all antibody identification panel cells were reactive at the same strength at the antihuman globulin phase,no negative reactions were observed,and the autocontrol was negative,what antibody should be suspected?
A) Multiple antibody specificities
B) Warm autoantibody
C) Antibody to a low-frequency antigen
D) Antibody to a high-frequency antigen

Accepted Answer

Reactions of similar strength suggest one specificity; a negative autocontrol rules out an autoantibody,and all panel cells reactive suggest an antibody to an antigen that is of high frequency in the population.

Question 5

High-titer,low-avidity antibodies typically:
A) react with antigens of high frequency in the population.
B) react with antigens of low frequency in the population.
C) are clinically significant.
D) react best at colder temperatures.

Accepted Answer

High-titer,low-avidity antibodies are typically reactive with most panel cells at the antihuman globulin phase and are not clinically significant.They may mask clinically significant reactions.

Question 6

What is the most important concern when trying to identify antibodies in a patient with a warm autoantibody?
A) Identifying the specificity of the autoantibody
B) Determining whether there are underlying alloantibodies
C) Identifying the antibody found in the eluate
D) Determining whether complement is binding to the autologous red cells

Accepted Answer

Autoantibodies in the serum can mask underlying alloantibodies.

Question 7

What is the next step in the investigation of a positive direct antiglobulin test with polyspecific antihuman globulin reagent?
A) Repeat the direct antiglobulin test using warm saline.
B) Perform an eluate.
C) Add IgG-sensitized red cells to verify positive reaction.
D) Repeat the direct antiglobulin test using monospecific anti-IgG and anti-C3 reagents.

Accepted Answer

Polyspecific antihuman globulin contains both a complement and IgG component.To determine which caused the positive reaction,red cells should be tested separately using monospecific anti-IgG and anti-C3 reagents.

Question 8

Select the example of a cold alloantibody. A) Anti-M. B) Anti-I. C) Anti-Lu^b. D) Anti-k.

Accepted Answer

Alloantibodies to anti-M react best at room temperature but can also demonstrate reactions at 37° C and antihuman globulin phases.

Question 9

Which of the following situations can be found in a classic case of autoimmune hemolytic anemia?
A) Positive direct antiglobulin test
B) False-positive Fyᵃ phenotyping
C) Crossmatch incompatibility at antihuman globulin
D) All of the above

Accepted Answer

Red cells of a patient with this condition are coated with IgG antibodies that are signaling premature destruction in the spleen.Because the red cells are coated,attempts to test them with antiglobulin reagent results in positive reactions.The antibody in the serum will react with all normal cells tested at the antihuman globulin phase.

Question 10

What type of red cells is used in an autoadsorption to remove antibody from the serum?
A) Antibody screening cells
B) Donor red cells
C) Patient red cells
D) Antibody identification panel cells

Accepted Answer

Patient red cells are treated to remove IgG antibody and then are incubated with the patient's serum to remove more autoantibodies that are interfering with alloantibody identification.

Question 11

Antibody screening cells are positive at the antihuman globulin phase of testing.What is the first step in this investigation?
A) Check transfusion and pregnancy history.
B) Perform a direct antiglobulin test using anti-C3.
C) Repeat the ABO typing.
D) Crossmatch units until one is compatible.

Accepted Answer

A positive screen indicates the presence of unexpected antibody.Patient history can aid in the investigation.

Question 12

In an antibody identification panel,only one red cell was negative at the antihuman globulin phase.On ruling out and matching the pattern,an anti-k was identified.What further testing is necessary to confirm the antibody?
A) Two more k-negative cells should be tested.
B) Two more K-negative cells should be tested.
C) Treat the panel cells with enzymes and perform the panel again.
D) Perform an adsorption using "k"-positive cells.

Accepted Answer

To satisfy the "rule of three," three negative and three positive reactions for the antigen should be observed to rule in an antibody.

Question 13

Select the best description of the elution technique.
A) Technique that disassociates IgM antibodies from red cells for further identification
B) Technique that disassociates IgG antibodies from red cells for further identification
C) Technique that adsorbs IgG antibodies from serum
D) Technique that separates IgG and IgM antibodies in serum

Accepted Answer

Elution procedures remove IgG antibodies from sensitized red cells to be used for identification using panel cells.

Question 14

If an anti-I is suspected in a patient's sample that requires a transfusion,what is the most acceptable course of action?
A) Call the rare donor registry.
B) Crossmatch cord blood.
C) Perform a cold autoadsorption.
D) Perform the prewarm technique.

Accepted Answer

Prewarming the patient's serum and panel cells separately and then mixing at 37° C to avoid cold temperatures usually avoids the reactivity of the anti-I,which is not clinically significant but may mask other antibodies.

Question 15

Why is the agglutination reaction phase important in the interpretation of the antibody screen or antibody identification panel?
A) Determines whether there is a delayed transfusion reaction
B) Provides clues on antibody dosage
C) Indicates the class of the antibody
D) Determines whether an autoantibody is present

Accepted Answer

IgM antibodies typically react at room temperature.IgG antibodies require the antiglobulin phase to detect.

Question 16

What is a characteristic of Rh system antibodies?
A) Mixed-field reactions on panels
B) Weak reactions with panel cells
C) Strong reactions with panel cells when read at immediate-spin phase
D) Reactions that are enhanced with enzymes

Accepted Answer

Rh system antibodies are typically strong and are enhanced with enzyme treatment.

Question 17

An autoadsorption may be performed to investigate underlying autoantibodies.When is this procedure acceptable?
A) When the autoantibody is reactive at 4° C
B) When the patient has not been recently transfused
C) Only if complement is coating the red cells
D) When the eluate is negative

Accepted Answer

If an autoadsorption is performed (using the patient's red cells)and the patient has been recently transfused,the adsorbing red cells may remove developing alloantibodies to the transfused cells.

Question 18

Select the antibody that is not produced against a low-incidence antigen. A) Anti-Vel B) Anti-C^w C) Anti-V D) Anti-Lu^a

Accepted Answer

Vel is an antigen found in high frequency in the population.

Question 19

Anti-Fyᵃ was identified in a patient's serum.The patient's red cells phenotyped as Fy(a+)using commercial antisera.What is the next step?
A) Repeat the panel to confirm the antibody.
B) Report the antibody because this result is normal.
C) Investigate a recent transfusion history.
D) Wash the cells and use monoclonal anti-Fyᵃ antibodies.

Accepted Answer

The patient's red cells should be Fy(a-)to make anti-Fyᵃ unless a recent transfusion was given of Fy(a+)red cells.If no Fy(a+)red cells were recently transfused,the antibody identified may be incorrect or the patient may have a positive direct antiglobulin test.

Question 20

What is the typical specificity of cold autoantibodies? A) M B) N C) I D) Le^b

Accepted Answer

Cold autoantibodies are typically of the specificity anti-I.I is a high-frequency antigen found on all adult red cells but is absent on cord red cells.

Quiz 8: Antibody Detection and Identification

In the process of identifying an antibody,the technologist observed 2+ reactions with 3 of the 10 cells in a panel at the immediate-spin phase.These reactions disappeared following incubation at 37° C and the antihuman globulin phase of testing.What is the most likely responsible antibody?

Which of the following antigens is not commonly used on screening cells?

Why are proteolytic enzymes not used in the routine screening for antibodies?

If all antibody identification panel cells were reactive at the same strength at the antihuman globulin phase,no negative reactions were observed,and the autocontrol was negative,what antibody should be suspected?

High-titer,low-avidity antibodies typically:

What is the most important concern when trying to identify antibodies in a patient with a warm autoantibody?

What is the next step in the investigation of a positive direct antiglobulin test with polyspecific antihuman globulin reagent?

Select the example of a cold alloantibody.

Which of the following situations can be found in a classic case of autoimmune hemolytic anemia?

What type of red cells is used in an autoadsorption to remove antibody from the serum?

Antibody screening cells are positive at the antihuman globulin phase of testing.What is the first step in this investigation?

In an antibody identification panel,only one red cell was negative at the antihuman globulin phase.On ruling out and matching the pattern,an anti-k was identified.What further testing is necessary to confirm the antibody?

Select the best description of the elution technique.

If an anti-I is suspected in a patient's sample that requires a transfusion,what is the most acceptable course of action?

Why is the agglutination reaction phase important in the interpretation of the antibody screen or antibody identification panel?

What is a characteristic of Rh system antibodies?

An autoadsorption may be performed to investigate underlying autoantibodies.When is this procedure acceptable?

Select the antibody that is not produced against a low-incidence antigen.

Anti-Fyᵃ was identified in a patient's serum.The patient's red cells phenotyped as Fy(a+) using commercial antisera.What is the next step?

What is the typical specificity of cold autoantibodies?