Question 1

"Complete" agglutinins that agglutinate red blood cells in saline are of which immunoglobulin class?

Accepted Answer

A)  IgG 
B)  IgM 
C)  IgA 
D)  IgE

Question 2

A patient came in for a routine type and screen prior to surgery. The antibody screen was negative at 37°C and at the AHG phase. Check cells did not produce agglutination often. What is a possible explanation for this result?

Accepted Answer

A)  Dirty glassware 
B)  Use of positive DAT cells 
C)  Inadequate washing 
D)  Over-centrifugation

Question 3

Polyspecific AHG contains:

Accepted Answer

A)  anti-IgG. 
B)  anti-C3b-C3d. 
C)  anti-IgG and anti- C3d. 
D)  anti-IgG and anti-IgM.

Question 4

Why is the 37°C reading omitted when using PEG additive?

Accepted Answer

A)  PEG may cause aggregation of RBCs at 37°C. 
B)  Antibodies detected by PEG do not react at 37°C. 
C)  Warm-reacting antibodies are not clinically significant. 
D)  Unwanted reactions due to C3b will be detected at 37°C.

Question 5

Saline used for blood banking tests should have a pH of ______________ .

Accepted Answer

A)  5.0 to 5.5 
B)  6.8 to 7.2 
C)  7.2 to 7.4 
D)  7.5 to 8.0

Question 6

In the production of polyspecific AHG, why are IgG and complement antibodies absorbed with A1, B, and O cells?

Accepted Answer

A)  To eliminate the possibility of prozone 
B)  To remove heterospecific antibody 
C)  To eliminate false-negative results 
D)  To standardize dilutions of antibody

Question 7

False-negative results in antihuman globulin testing can be caused by:

Accepted Answer

A)  over-centrifugation. 
B)  under-centrifugation. 
C)  cell suspensions that are too weak or too heavy. 
D)  all of the above.

Question 8

An advantage of polyclonal anti-IgG over monoclonal anti-IgG is:

Accepted Answer

A)  AHG produced in rabbits is more specific than AHG produced in mice. 
B)  polyclonal anti-IgG will recognize IgG variants. 
C)  polyclonal anti-IgG also has anticomplement activity. 
D)  polyclonal anti-IgG recognizes only one IgG epitope.

Question 9

Anti-IgG is specific for what part of the IgG molecule?

Accepted Answer

A)  FC fragment 
B)  Constant region of Fab fragment 
C)  Hypervariable region of Fab fragment 
D)  Kappa light chain

Question 10

Why was anticomplement introduced into AHG sera?

Accepted Answer

A)  Certain clinically significant antibodies demonstrate complement activity. 
B)  Complement components enhance Kell antibodies. 
C)  It provides additional information for transfusion reaction workups. 
D)  All of the above

Question 11

How is polyclonal antiglobulin serum made?

Accepted Answer

A)  Serum from one human is injected into another human, and an antibody is produced. 
B)  Human serum is injected into rabbits, and an immune response triggers the production of an antibody. 
C)  Murine serum is injected into rabbits, and an immune response triggers the production of an antibody. 
D)  Murine serum is injected into mice, and an immune response triggers the production of an antibody.

Question 12

Which of the following is consistent with hemolytic disease of the newborn (HDN)?

Accepted Answer

A)  Recipient antibody coating donor red blood cells 
B)  Maternal antibody coating fetal red blood cells 
C)  Fetal antibody coating maternal red blood cells 
D)  Autoantibody coating individual's own red blood cells

Question 13

What is the purpose of washing cells in the AHG test?

Accepted Answer

A)  To dilute serum 
B)  To remove all unbound protein 
C)  To remove all bound protein 
D)  To exclude a low-affinity antibody

Question 14

Which IgG antibodies are contained in polyspecific AHG?

Accepted Answer

A)  High titer, high avidity 
B)  High titer, low avidity 
C)  Chemically modified 
D)  Those that are pentameric in structure

Question 15

All of the following conditions may produce a positive DAT except:

Accepted Answer

A)  hemolytic disease of the newborn. 
B)  hemolytic transfusion reaction. 
C)  lymphoma. 
D)  drug-induced hemolytic anemia.

Question 16

What type of globulin does the antiglobulin test detect?

Accepted Answer

A)  IgG alloantibodies 
B)  IgG autoantibodies 
C)  C3b complement components 
D)  All of the above

Question 17

What is the incubation time for the IAT when saline is used instead of LISS?

Accepted Answer

A)  10 minutes 
B)  15 minutes 
C)  30 minutes 
D)  1 hour

Question 18

A patient is discovered to have anti-Fya in their serum. The medical technologist needs to phenotype the patient's cells for the corresponding antigen. What test is appropriate for phenotyping?

Accepted Answer

A)  Absorption 
B)  Elution 
C)  DAT 
D)  IAT

Question 19

An antibody screen is performed, and all three tubes are negative after adding AHG. Check cells are added, and the tubes are centrifuged. No agglutination occurs after the addition of check cells. What is the next course of action?

Accepted Answer

A)  Recentrifuging the tubes 
B)  Adding one drop of control cells 
C)  Repeating the antibody screen 
D)  Adding one drop of AHG

Question 20

What effect does a low pH have on a saline AHG test?

Accepted Answer

A)  Enhances antibody elution 
B)  Enhances the antigen-antibody complex 
C)  Increases hydrogen bonding 
D)  Increases bacterial contamination

Exam 5: The Antiglobulin Test