Deck 7: Antibody Detection and Identification

Question 1

The next step in investigating a positive direct antiglobulin test using polyspecific antihuman globulin reagent should be to:

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.

Answer 1

D
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 2

The best description of the elution technique is that it is a technique used to:

A)disassociate IgM antibodies from red cells for further identification.
B)disassociate IgG antibodies from red cells for further identification.
C)adsorb IgG antibodies from serum.
D)separate IgG and IgM antibodies in serum.

Answer 2

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

Question 3

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

Answer 3

B
Autoantibodies in the serum can mask underlying alloantibodies.

Question 4

An example of a cold alloantibody includes:

A)anti-M.
B)anti-I.
C)anti-Lu^b.
D)anti-k.

Question 5

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

Question 6

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 ^$\circ$ C and the antihuman globulin phase of testing.The antibody most likely to be responsible is:

A)anti-E.
B)anti-D.
C)anti-I.
D)anti-Le^a.

Question 7

Antibody screening cells are positive at the antihuman globulin phase of testing.The first step of the investigation should be to:

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.

Question 8

Rh system antibodies characteristically give:

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.

Question 9

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

A)Multiple antibody specificities
B)Warm autoantibody
C)Antibody to a low-frequency antigen
D)Antibody to a high-frequency antigen

Question 10

The phase of the agglutination reaction is important in the interpretation of the antibody screen or antibody identification panel because it:

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.

Question 11

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.

Question 12

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.

Question 13

An autoadsorption uses what type of cells to remove antibody from the serum?

A)Antibody screening cells
B)Donor red cells
C)Patient red cells
D)Antibody identification panel cells

Question 14

Proteolytic enzymes should not be used to screen for antibodies because:

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.

Question 15

All the following antigens are commonly found on screening cells except:

A)D.
B)k.
C)Kp^a.
D)C.

Question 16

An anti-Fy^a was identified in a patient's serum.The patient's red cells phenotyped as Fy^a positive using commercial antisera.The next step is to:

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-Fy^a antibodies.

Question 17

Cold autoantibodies are typically of which specificity?

A)M
B)N
C)I
D)Le^b

Question 18

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

A)Positive direct antiglobulin test
B)False-positive Fy^a phenotyping
C)Crossmatch incompatibility at antihuman globulin
D)All of the above

Question 19

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

A)call the rare donor registry.
B)crossmatch cord blood.
C)perform a cold autoadsorption.
D)perform the prewarm technique.

Question 20

Antibodies to low-incidence antigens include all of the following except:

A)anti-Vel.
B)anti-C^w.
C)anti-V.
D)anti-Lu^a.

Question 21

DTT (dithiothreitol)would be useful in the identification of which of the following antibodies?

A)Anti-Js^a
B)Anti-Kp^b
C)Anti-Vel
D)Anti-K

Question 22

A patient's serum reacted weakly with all panel cells tested at the antiglobulin phase using LISS and were not enhanced using PEG.The autocontrol was negative.Ficin-treated panel cells were nonreactive.What is the most likely specificity of the antibody?

A)Anti-I
B)Anti-U
C)Anti-Ch
D)Anti-Js^b

Question 23

Match the tentative interpretation of antibody screen and direct antiglobulin test (DAT)with the results given below.a.Alloantibody,IgG
b.Alloantibody,IgM
c.Autoantibody,IgM
d.Autoantibody or transfusion reaction,IgG
All screening cells 2+ at antihuman globulin phase,DAT positive,IgG 2+

Question 24

Anti-Sd^a should be suspected if:

A)weak reactions at the antiglobulin phase occur with several panel cells.
B)reactions are stronger with enzymes at the immediate spin phase.
C)the antibody reacts with most panel cells and are mixed field and refractile microscopically.
D)weak reactions at the AHG phase titer out to high dilutions.

Question 25

Match the tentative interpretation of antibody screen and direct antiglobulin test (DAT)with the results given below.a.Alloantibody,IgG
b.Alloantibody,IgM
c.Autoantibody,IgM
d.Autoantibody or transfusion reaction,IgG
One screening cell 1+ at antihuman globulin phase,DAT negative

Question 26

Which of the following medications is most likely to cause the production of autoantibodies?

A)Tetracycline
B)Cephalothin
C)Methyldopa
D)Acutane

Question 27

An antibody was detected at immediate spin and 37° C that appeared to have anti-Le^b specificity.To confirm the antibody identity and determine if there were other antibodies in the serum,a Lewis neutralization technique was performed.Results of the control are as follows: Reaction with Le(b)positive cells
Patient serum + Lewis substance 0
Patient serum + saline control 1+
What conclusion can be made from these results?

A)anti-Le^b is confirmed
B)the antibody was diluted,therefore no conclusion can be made
C)the antibody was not neutralized,therefore anti-Le^b has not been identified
D)an antibody other than anti-Leb is most likely in the serum

Question 28

Anti-D,anti-K,and anti-Jk^a are the antibodies that are tentatively identified on a panel after initially ruling out on negative cells.What selected cell from another panel should be chosen to confirm the presence of anti-K?

A)K-,D+,Jk(a+)
B)K+,D+,Jk(a+)
C)K+,D-,Jk(a+)
D)K+,D-,Jk(a-)

Question 29

Match the tentative interpretation of antibody screen and direct antiglobulin test (DAT)with the results given below.a.Alloantibody,IgG
b.Alloantibody,IgM
c.Autoantibody,IgM
d.Autoantibody or transfusion reaction,IgG
All screening cells positive 1+ at IS,DAT positive,C3 1+

Question 30

Match the tentative interpretation of antibody screen and direct antiglobulin test (DAT)with the results given below.a.Alloantibody,IgG
b.Alloantibody,IgM
c.Autoantibody,IgM
d.Autoantibody or transfusion reaction,IgG
All screening cells positive 1+ at IS,DAT negative