Deck 7: Antibody Detection and Identification

Question 1

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

Answer 1

C
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 2

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.

Answer 2

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

Question 3

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.

Answer 3

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

Question 4

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 5

Cold autoantibodies are typically of which specificity?

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

Question 6

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.

Question 7

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.

Question 8

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 9

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 10

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 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

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 13

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 14

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 15

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 16

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 17

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 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

An example of a cold alloantibody includes:

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

Question 20

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

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

Question 21

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
Both screening cells 2+ at antihuman globulin phase, DAT positive, IgG 2+

Question 22

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 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
One screening cell 1+ at antihuman globulin phase, DAT negative

Question 24

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 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
Both screening cells positive 1+ at IS, DAT positive, C3 1+

Question 26

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
Both screening cells positive 1+ at IS, DAT negative