Immunology- Hypersensitivity

Question 1

1. Which of the following is a description of a type I
   hypersensitivity reaction?
   A. Ragweed antigen cross links with IgE on the surface
   of mast cells, causing release of preformed mediators
   and resulting in symptoms of an allergic reaction
   B. Anti-Fya from a pregnant woman crosses the
   placenta and attaches to the Fya antigen-positive
   red cells of the fetus, destroying the red cells
   C. Immune complex deposition occurs on the
   glomerular basement membrane of the kidney,
   leading to renal failure
   D. Exposure to poison ivy causes sensitized T cells
   to release lymphokines that cause a localized
   inflammatory reaction

Answer 1

A. Ragweed antigen cross links with IgE on the surface
of mast cells, causing release of preformed mediators
and resulting in symptoms of an allergic reaction

Question 2

2. Why is skin testing the most widely used method
   to test for a type I hypersensitivity reaction?
   A. It causes less trauma and is more cost effective
   than other methods
   B. It has greater sensitivity than in vitro measurements
   C. It is more likely to be positive for IgE-specific
   allergens than other methods
   D. It may be used to predict the development of
   further allergen sensitivity

Answer 2

B. It has greater sensitivity than in vitro measurements

Question 3

3. Which in vitro test measures IgE levels against a
   specific allergen?
   A. Histamine release assay
   B. Radioimmunosorbent test (RIST)
   C. Fluorescent allergosorbent test (FAST)
   D. Precipitin radioimmunosorbent test (PRIST)

Answer 3

C. Fluorescent allergosorbent test (FAST)

Question 4

4. A patient who is blood group O is accidentally
   transfused with group A blood and develops a
   reaction during the transfusion. What antibody
   is involved in this type II reaction?
   A. IgM
   B. IgE
   C. IgG and IgE
   D. IgG

Answer 4

A. IgM

Question 5

5. Which test would measure the coating of red cells
   by antibody as occurs in hemolytic transfusion
   reactions?
   A. Indirect antiglobulin test (IAT)
   B. Direct antiglobulin test (DAT)
   C. ELISA
   D. Hemagglutination

Answer 5

B. Direct antiglobulin test (DAT)

Question 6

6. Which test detects antibodies that have attached to
   tissues, resulting in a type-II cytotoxic reaction?
   A. Migration inhibition factor assay (MIF)
   B. Direct immunofluorescence (IF)
   C. Immunofixation electrophoresis (IFE)
   D. Hemagglutination

Answer 6

B. Direct immunofluorescence (IF)

Question 7

7. Which of the following conditions will most likely
   result in a false-negative DAT test?
   A. Insufficient washing of RBCs
   B. Use of heavy chain–specific polyclonal
   anti-human Ig
   C. Use of excessive centrifugal force
   D. Use of a sample obtained by finger puncture

Answer 7

A. Insufficient washing of RBCs

Question 8

8. Which of the following tests is used to detect
   circulating immune complexes in the serum of
   some patients with systemic autoimmune diseases
   such as rheumatoid arthritis?
   A. Direct immunofluorescence
   B. Enzyme immunoassay
   C. Assay of cryoglobulins
   D. Indirect antiglobulin test

Answer 8

C. Assay of cryoglobulins

Question 9

9. All of the following tests may be abnormal in a
   type III immune complex reaction except:
   A. C1q-binding assay by ELISA
   B. Raji cell assay
   C. CH50 level
   D. Mitogen response

Answer 9

D. Mitogen response

Question 10

10. What immune elements are involved in a positive
    skin test for tuberculosis?
    A. IgE antibodies
    B. T cells and macrophages
    C. NK cells and IgG antibody
    D. B cells and IgM antibody

Answer 10

B. T cells and macrophages

Question 11

11. A patient receives a transfusion of packed red
    cells and fresh frozen plasma and develops an
    anaphylactic, nonhemolytic reaction. She reports
    receiving a transfusion 20 years earlier. She had
    no reaction to the previous transfusion, but she
    did feel “poorly” a few weeks later. Which of the
    following transfused substances most likely elicited
    the reaction?
    A. IgA
    B. Group A antigen
    C. Rho (D) antigen
    D. An antigen belonging to the Duffy system

Answer 11

A. IgA

Question 12

12. A patient deficient in the C3 complement
    component would be expected to mount a
    normal:
    A. Type I and IV hypersensitivity response
    B. Type II and IV hypersensitivity response
    C. Type I and III hypersensitivity response
    D. Type II and III hypersensitivity response

Answer 12

A. Type I and IV hypersensitivity response