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BOC review-Harr 5th ed > Blood bank 4.4 Testing for Antibodies > Flashcards

Blood bank 4.4 Testing for Antibodies Flashcards

1
Q
  1. A patient has the Lewis phenotype Le(a-b-). An antibody panel reveals the presence of anti-Lea. Another patient with the phenotype Le(a-b+) has a positive antibody screen; however, a panel reveals no conclusive antibody. Should anti-Lea be considered a possibility for the patient with the Le(a-b+) phenotype?

A. Anti-Lea should be considered as a possible antibody
B. Anti-Lea may be a possible antibody, but further studies are needed
C. Anti-Lea is not a likely antibody because even Leb individuals secrete some Lea
D. Anti-Lea may be found in saliva but not detectable in serum

A

C. Anti-Lea is not a likely antibody because even Leb individuals secrete some Lea

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2
Q
  1. A medical laboratory scientist (MLS) is having great difficulty resolving an antibody mixture. One of the antibodies is anti-Lea. This antibody is not clinically significant in this situation, but it needs to be removed to reveal the possible presence of an underlying antibody of clinical significance. What can be done?

A. Perform an enzyme panel
B. Neutralize the serum with saliva
C. Neutralize the serum with hydatid cyst fluid
D. Use dithiothreitol (DTT) to treat the panel cells

A

B. Neutralize the serum with saliva

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3
Q
  1. What type of blood should be given to an individual who has anti-Leb that reacts 1+ at the IAT phase?
    A. Blood that is negative for Leb antigen
    B. Blood that is negative for both Lea and Leb antigens
    C. Blood that is positive for Leb antigen
    D. Lewis antibodies are not clinically significant, so any type of blood may be given
A

A. Blood that is negative for Leb antigen

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4
Q
  1. Which of the following statements is true concerning the MN genotype?
    A. Antigens are destroyed using bleach-treated cells
    B. Dosage effect may be seen for both M and N antigens
    C. Both M and N antigens are impossible to detect because of cross-interference
    D. MN is a rare phenotype seldom found in routine antigen typing
A

B. Dosage effect may be seen for both M and N antigens

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5
Q
  1. Anti-M is sometimes found with reactivity detected at the immediate spin (IS) phase that persists in strength to the IAT phase. What is the main testing problem with a strong anti-M?
    A. Anti-M may not allow detection of a clinically significant antibody
    B. Compatible blood may not be found for the patient with a strongly reacting anti-M
    C. Anti-M cannot be removed from serum
    D. Anti-M may react with the patient’s own cells, causing a positive autocontrol
A

A. Anti-M may not allow detection of a clinically significant antibody

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6
Q
  1. A patient is suspected of having paroxysmal cold hemoglobinuria (PCH). Which pattern of reactivity is characteristic of the Donath-Landsteiner antibody, which causes this condition?
    A. The antibody attaches to RBCs at 4°C and causes hemolysis at 37°C
    B. The antibody attaches to RBCs at 37°C and causes agglutination at the IAT phase
    C. The antibody attaches to RBCs at 22°C and causes hemolysis at 37°C
    D. The antibody attaches to RBCs and causes agglutination at the IAT phase
A

A. The antibody attaches to RBCs at 4°C and causes hemolysis at 37°C

The Donath-Landsteiner antibody has anti-P specificity with biphasic activity. The antibody attaches to RBCs at 4°C and then causes the RBCs to hemolyze when warmed to 37°C.

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7
Q
  1. How can interfering anti-P1 antibody be removed from a mixture of antibodies?
    A. Neutralization with saliva
    B. Agglutination with human milk
    C. Combination with urine
    D. Neutralization with hydatid cyst fluid
A

D. Neutralization with hydatid cyst fluid

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8
Q
  1. Which antibody is frequently seen in patients with warm autoimmune hemolytic anemia (WAIHA)?
    A. Anti-Jka
    B. Anti-e
    C. Anti-K
    D. Anti-Fyb
A

B. Anti-e

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9
Q
  1. A patient’s antibody shows strong reactions in all test phases. All screen and panel cells are positive. Serum is then tested with a cord blood cell, and the reaction is negative. What antibody is suspected?
    A. Anti-I
    B. Anti-i
    C. Anti-H
    D. Anti-p
A

A. Anti-I

Adult cells contain mostly I antigen, and anti-I would react with all adult cells found on screen or panel cells. Cord blood cells, however, contain mostly i antigen and would test negative or only weakly positive with anti-I.

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10
Q
  1. Which group of antibodies is commonly found as cold agglutinins?
    A. Anti-K, anti-k, anti-Jsb
    B. Anti-D, anti-e, anti-C
    C. Anti-M, anti-N
    D. Anti-Fya, anti-Fyb
A

C. Anti-M, anti-N

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11
Q
  1. Which of the following antibodies characteristically gives a refractile mixed-field appearance?
    A. Anti-K
    B. Anti-Dia
    C. Anti-Sda
    D. Anti-s
A

C. Anti-Sda

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12
Q
  1. What does the 3+3 rule ascertain?
    A. An antibody is ruled in
    B. An antibody is ruled out
    C. 95% confidence that the correct antibody has been identified
    D. 95% confidence that the correct antibody has not been identified
A

C. 95% confidence that the correct antibody has been identified

The 3+3 rule ascertains correct identification of antibody at a confidence level of 95%. For this level to be met, reagent RBCs are found containing target antigen to suspected antibody that react in test phase; likewise, reagent RBCs devoid of antigen will not react in test phase.

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13
Q
  1. The k (Cellano) antigen is a high-frequency antigen and is found on most RBCs. How often would one expect to find the corresponding antibody?
    A. Often, because it is a high-frequency antibody
    B. Rarely, because most individuals have the antigen and therefore would not develop the antibody
    C. Depends on the population, because certain racial and ethnic groups show a higher frequency of anti-k
    D. Impossible to determine without consulting regional blood group antigen charts
A

B. Rarely, because most individuals have the antigen and therefore would not develop the antibody

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14
Q
  1. Which procedure would help to distinguish between anti-e and anti-Fya in an antibody mixture?
    A. Lowering the pH of test serum
    B. Running an enzyme panel
    C. Using a thiol reagent
    D. Running an LISS panel
A

B. Running an enzyme panel

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15
Q
  1. Which characteristics are true of all three of the following antibodies: anti-Fya, anti-Jka, and anti-K?
    A. Detected at the IAT phase; may cause hemolytic disease of the fetus and newborn (HDFN) and hemolytic transfusion reactions
    B. Not detected with enzyme-treated cells
    C. Requires the IAT technique for detection; usually not associated with HDFN
    D. Enhanced reactivity with enzyme-treated cells; may cause severe hemolytic transfusion reactions
A

A. Detected at the IAT phase; may cause hemolytic disease of the fetus and newborn (HDFN) and hemolytic transfusion reactions

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16
Q
  1. A patient is admitted to the hospital. Medical records indicate that the patient has a history of anti-Jka. When you performed the type and screen, the type was O positive, and the screen was negative. You should:
    A. Crossmatch using units negative for Jka antigen
    B. Crossmatch random units, since the antibody is not demonstrating
    C. Request a new sample
    D. Repeat the screen with enzyme-treated screening cells
A

A. Crossmatch using units negative for Jka antigen

17
Q
  1. An MLS performs an antibody study and finds 1+ and weak positive reactions for several of the panel cells. The reactions do not fit a pattern. Several selected panels and a patient phenotype do not reveal any additional information. Serum is diluted and retested, but the same reactions persist. What type of antibody may be causing these results?

A. Antibody to a high-frequency antigen
B. Antibody to a low-frequency antigen
C. High titer low avidity (HTLA)
D. Anti-human leukocyte antigen (anti-HLA)

A

C. High titer low avidity (HTLA)

HTLA antibodies may persist in reaction strength, even when diluted. These antibodies are directed against high-frequency antigens (e.g., Cha ). They are not clinically significant but, when present, are responsible for a high incidence of incompatible crossmatches.

18
Q
  1. An antibody is detected in a pregnant woman and is suspected of being the cause of fetal distress. The antibody reacts at the IAT phase but does not react with DTT-treated cells. This antibody causes in vitro hemolysis. What is the most likely antibody specificity?
    A. Anti-Lea
    B. Anti-Lua
    C. Anti-Lub
    D. Anti-Xga
A

C. Anti-Lub

Of the antibodies listed, only Lub is detected in the IAT phase, causes in vitro hemolysis, may cause HDFN, and does not react with DTT-treated cells.

19
Q
  1. What sample is best for detecting complement-dependent antibodies?
    A. Plasma stored at 4°C for no longer than 24 hours
    B. Serum stored at 4°C for no longer than 48 hours
    C. Either serum or plasma stored at 20°C to 24°C no longer than 6 hours
    D. Serum heated at 56°C for 30 minutes
A

B. Serum stored at 4°C for no longer than 48 hours

Serum stored at 4°C for no longer than 48 hours preserves complement activity. Plasma is inappropriate because most anticoagulants chelate calcium needed for activation of complement. Heating the serum to 56°C destroys complement.

20
Q
  1. Which antibody would not be detected by group O screening cells?
    A. Anti-N
    B. Anti-A1
    C. Anti-Dia
    D. Anti-k
A

B. Anti-A1

21
Q
  1. Refer to Panel 1. (pg 208) Which antibody is most likely implicated?
    A. Anti-Fyb
    B. Anti-Jkb
    C. Anti-e
    D. Anti-c and anti-K
A

B. Anti-Jkb

The pattern clearly fits that of anti-Jkb, an antibody that usually reacts best at IAT. The weaker reactions are caused by the dosage effect found on cells that are heterozygous for the Jkb antigen

22
Q
  1. Refer to Panel 2. (pg 209) Which antibody specificity is most likely present?
    A. Anti-S and anti-E
    B. Anti-E and anti-K
    C. Anti-Lea and anti-Fyb
    D. Anti-C and anti-K
A

D. Anti-C and anti-K

The pattern fits anti-C at 37°C, which becomes stronger at the IAT phase. The additional antibody is anti-K, which appears only at the IAT phase.

23
Q
  1. On Panel 2 (pg 209), which of the following antibodies could not be ruled out?
    A. Anti-Jkb
    B. Anti-C
    C. Anti-M
    D. Anti-Fyb
A

B. Anti-C

24
Q
  1. On Panel 2 (pg 209), which cells are homozygous for C?
    A. 1, 2, 3
    B. 1, 2, 9
    C. 3, 4, 7
    D. 7, 8, 10
A

B. 1, 2, 9

25
Q
  1. A 77-year-old female is admitted to a community hospital after a cardiac arrest. History includes an abdominal aortic aneurysm 2 years ago for which she received 6 units of packed RBCs. Her blood type is A positive, and the antibody screen is positive at the AHG phase in screening cells II and III. A panel is performed by using LISS. In Panel 3 (pg 210), which antibodies are likely implicated?
    A. C and K
    B. Jka and c
    C. E and c
    D. Fya and M
A

C. E and c

The antibodies evident in Panel 3 are E and c. Every positive reaction at 37°C and IAT phases are positive for either the E antigen and/or for cells homozygous for c antigen.

26
Q
  1. What observation is apparent with one of the antibodies present on Panel 3? (pg 210)
    A. One antibody is only reacting with heterozygous cells
    B. Both antibodies are only reacting with homozygous cells
    C. One antibody is only reacting with homozygous cells
    D. Both antibodies are exhibiting dosage
A

C. One antibody is only reacting with homozygous cells

Anti-c is only reacting with homozygous cells.

BOC review-Harr 5th ed (41 decks)

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