Deck 8: Antibody Detection and Identification

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

Answer 1

Anti-Le^a

Question 2

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

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

Answer 2

Kp^a

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.

Answer 3

D
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

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.

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

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.

Question 8

Select the example of a cold alloantibody.

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

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

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

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.

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.

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

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.

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

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

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

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

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.

Question 20

What is the typical specificity of cold autoantibodies?

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

Question 21

Anti-D,anti-K,and anti-Jkᵃ 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 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

MATCHING
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

Question 24

MATCHING
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 25

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

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

Question 26

MATCHING
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 27

An antibody was detected at immediate-spin and 37° C that appeared to have anti-Le? specificity.To confirm the antibody identity and determine if there were other antibodies in the serum,a Lewis neutralization technique was performed.
Patient serum + Lewis substance = 0
Patient serum + saline control = 1+
Neutralized serum + Fy(a+b+)red cell = 0
What conclusion can be made from these results?

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

Question 28

Select the antibody where DTT (dithiothreitol)would be useful in the identification investigation.

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

Question 29

MATCHING
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

When should anti-Sdᵃ be suspected?

A) Weak reactions at the antiglobulin phase occur with several panel cells
B) Reactions are stronger with enzymes at the immediate-spin phase
C) 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