immunology-Immunology Problem Solving

Question 1

1. Which of the following serial dilutions contains an
   incorrect factor?
   A. 1:4, 1:8, 1:16
   B. 1:1, 1:2, 1:4
   C. 1:5, 1:15, 1:45
   D. 1:2, 1:6, 1:12

Answer 1

D. 1:2, 1:6, 1:12

Question 2

2. A patient was tested for syphilis by the RPR
   method and was reactive. An FTA-ABS test was
   performed and the result was negative. Subsequent
   testing showed the patient to have a high titer of
   anticardiolipin antibodies (ACAs) by the ELISA
   method. Which routine laboratory test is most
   likely to be abnormal for this patient?
   A. Activated partial thromboplastin time (APTT)
   B. Antismooth muscle antibodies
   C. Aspartate aminotransferase (AST)
   D. C3 assay by immunonephelometry

Answer 2

A. Activated partial thromboplastin time (APTT)

Question 3

3. Inflammation involves a variety of biochemical
   and cellular mediators. Which of the following
   may be increased within 72 hours after an initial
   infection?
   A. Neutrophils, macrophages, antibody, complement,
   α1-antitrypsin
   B. Macrophages, T cells, antibody, haptoglobin,
   fibrinogen
   C. Neutrophils, macrophages, complement,
   fibrinogen, C-reactive protein
   D. Macrophages, T cells, B cells, ceruloplasmin,
   complement

Answer 3

C. Neutrophils, macrophages, complement,
fibrinogen, C-reactive protein

Question 4

4. An 18-month-old boy has recurrent sinopulmonary
   infections and septicemia. Bruton’s X-linked
   immunodeficiency syndrome is suspected. Which
   test result would be markedly decreased?
   A. Serum IgG, IgA, and IgM
   B. Total T-cell count
   C. Both B- and T-cell counts
   D. Lymphocyte proliferation with
   phytohemagglutinin stimulation

Answer 4

A. Serum IgG, IgA, and IgM

Question 5

5. A patient received 5 units of fresh frozen plasma
   (FFP) and developed a severe anaphylactic
   reaction. He has a history of respiratory and
   gastrointestinal infections. Post-transfusion studies
   showed all 5 units to be ABO-compatible. What
   immunologic test would help to determine the
   cause of this transfusion reaction?
   A. Complement levels, particularly C3 and C4
   B. Flow cytometry for T-cell counts
   C. Measurement of immunoglobulins
   D. NBT test for phagocytic function

Answer 5

C. Measurement of immunoglobulins

Question 6

6. An IFE revealed excessive amounts of polyclonal
   IgM and low concentrations of IgG and IgA. What
   is the most likely explanation of these findings and
   the best course of action?
   A. Proper amounts of antisera were not added;
   repeat both tests
   B. Test specimen was not added properly; repeat
   both procedures
   C. Patient has common variable immunodeficiency;
   perform B-cell count
   D. Patient has immunodeficiency with hyper-M;
   perform immunoglobulin levels

Answer 6

D. Patient has immunodeficiency with hyper-M;
perform immunoglobulin levels

Question 7

7. SITUATION: A 54-year-old man was admitted
   to the hospital after having a seizure. Many
   laboratory tests were performed, including an
   RPR, but none of the results were positive. The
   physician suspects a case of late (tertiary) syphilis.
   Which test should be performed next?
   A. Repeat RPR, then perform VDRL
   B. Treponemal test such as MHA-TP on serum
   C. VDRL on CSF
   D. No laboratory test is positive for late (tertiary)
   syphilis

Answer 7

B. Treponemal test such as MHA-TP on serum

Question 8

8. A patient came to his physician complaining of a
   rash, severe headaches, stiff neck, and sleep
   problems. Laboratory tests of significance were an
   elevated sedimentation rate (ESR) and slightly
   increased liver enzymes. Further questioning of the
   patient revealed that he had returned from a
   hunting trip in upstate New York 4 weeks ago. His
   physician ordered a serological test for Lyme
   disease, and the assay was negative. What is the
   most likely explanation of these results?
   A. The antibody response is not sufficient to be
   detected at this stage
   B. The clinical symptoms and laboratory results are
   not characteristic of Lyme disease
   C. The patient likely has an early infection with
   hepatitis B virus
   D. Laboratory error has caused a false-negative result

Answer 8

A. The antibody response is not sufficient to be
detected at this stage

Question 9

9. A 19-year-old girl came to her physician
   complaining of a sore throat and fatigue. Upon
   physical examination, lymphadenopathy was
   noted. Reactive lymphocytes were noted on
   the differential, but a rapid test for IM
   antibodies was negative. Liver enzymes were
   only slightly elevated. What test(s) should be
   ordered next?
   A. Hepatitis testing
   B. EBV serological panel
   C. HIV confirmatory testing
   D. Bone marrow biopsy

Answer 9

B. EBV serological panel

Question 10

10. A patient received 2 units of RBCs following
    surgery. Two weeks after the surgery, the patient
    was seen by his physician and exhibited mild
    jaundice and slightly elevated liver enzymes.
    Hepatitis testing, however, was negative. What
    should be done next?
    A. Nothing until more severe or definitive clinical
    signs develop
    B. Repeat hepatitis testing immediately
    C. Repeat hepatitis testing in a few weeks
    D. Check blood bank donor records and contact
    donor(s) of transfused units

Answer 10

C. Repeat hepatitis testing in a few weeks

Question 11

11. A hospital employee received the final dose of the
    hepatitis B vaccine 3 weeks ago. She wants to
    donate blood. Which of the following results are
    expected from the hepatitis screen, and will she be
    allowed to donate blood?
    A. HBsAg, positive; anti-HBc, negative—she may
    donate
    B. HBsAg, negative; anti-HBc, positive—she may
    not donate
    C. HBsAg, positive; anti-HBc, positive—she may
    not donate
    D. HBsAg, negative; anti-HBc, negative—she may
    donate

Answer 11

D. HBsAg, negative; anti-HBc, negative—she may
donate

Question 12

12. A pregnant woman came to her physician with a
    maculopapular rash on her face and neck. Her
    temperature was 37.7°C (100°F). Rubella tests for
    both IgG and IgM antibody were positive. What
    positive test(s) would reveal a diagnosis of
    congenital rubella syndrome in her baby after
    birth?
    A. Positive rubella tests for both IgG and IgM
    antibody
    B. Positive rubella test for IgM
    C. Positive rubella test for IgG
    D. No positive test is revealed in congenital rubella
    syndrome

Answer 12

B. Positive rubella test for IgM

Question 13

13. SITUATION: A patient with RA has acute
    pneumonia but a negative throat culture. The
    physician suspects an infection with Mycoplasma
    pneumoniae and requests an IgM-specific antibody
    test. The test is performed directly on serial
    dilutions of serum less than 4 hours old. The result
    is positive, giving a titer of 1:32. However, the test
    is repeated 3 weeks later, and the titer remains at
    1:32. What best explains these results?
    A. IgM-specific antibodies do not increase fourfold
    between acute and convalescent serum
    B. The results are not significant because the initial
    titer was not accompanied by a positive test for
    cold agglutinins
    C. Rheumatoid factor caused a false-positive test
    result
    D. Insufficient time had elapsed between
    measurement of acute and convalescent
    samples

Answer 13

C. Rheumatoid factor caused a false-positive test
result

Question 14

14. A patient has a prostate-specific antigen level of
    60 ng/mL the day before surgery to remove a
    localized prostate tumor. One week following
    surgery, the serum PSA was determined to be
    8 ng/mL by the same method. What is the most
    likely cause of these results?
    A. Incomplete removal of the malignancy
    B. Cross reactivity of the antibody with another
    tumor antigen
    C. Testing too soon after surgery
    D. Hook effect with the PSA assay

Answer 14

C. Testing too soon after surgery

Question 15

15. A patient with symptoms associated with SLE and
    scleroderma was evaluated by immunofluorescence
    microscopy for ANAs using the HEp-2 cell line as
    substrate. The cell line displayed a mixed pattern
    of fluorescence that could not be separated by
    serial dilutions of the serum. Which procedure
    would be most helpful in determining the
    antibody profile of this patient?
    A. Use of a different tissue substrate
    B. Absorption of the serum using the appropriate
    tissue extract
    C. Ouchterlony technique
    D. ELISA tests for specific antibodies

Answer 15

D. ELISA tests for specific antibodies

Question 16

16. A patient with joint swelling and pain tested
    negative for serum RF by both latex agglutination
    and ELISA methods. What other test would help
    establish a diagnosis of RA in this patient?
    A. Anti CCP
    B. ANA testing
    C. Flow cytometry
    D. Complement levels

Answer 16

A. Anti CCP

Question 17

17. What is the main advantage of the recovery and
    reinfusion of autologous stem cells?
    A. It slows the rate of rejection of transplanted cells
    B. It prevents graft-versus-host disease
    C. No HLA testing is required
    D. Engraftment occurs in a more efficient sequence

Answer 17

B. It prevents graft-versus-host disease

Question 18

18. A transplant patient began to show signs of
    rejection 8 days after receipt of the transplanted
    organ, and the organ was removed. What immune
    elements might be found in the rejected organ?
    A. Antibody and complement
    B. Primarily antibody
    C. Macrophages
    D. T cells

Answer 18

D. T cells

Question 19

19. A patient with ovarian cancer who has been treated
    with chemotherapy is being monitored for
    recurrence using serum CA-125, CA-50, and CA
    15–3. Six months after treatment the CA 15–3 is
    elevated, but the CA-125 and CA-50 remain low.
    What is the most likely explanation of these findings?
    A. Ovarian malignancy has recurred
    B. CA 15–3 is specific for breast cancer and
    indicates metastatic breast cancer
    C. Testing error occurred in the measurement of
    CA 15–3 caused by poor analytical specificity
    D. The CA 15–3 elevation is spurious and probably
    benign

Answer 19

A. Ovarian malignancy has recurred

Question 20

20. An initial and repeat ELISA test for antibodies to
    HIV-1 are both positive. A Western blot shows a
    single band at gp160. The patient shows no
    clinical signs of HIV infection, and the patient’s
    CD4 T-cell count is normal. Based upon these
    results, which conclusion is correct?
    A. Patient is diagnosed as HIV-1-positive
    B. Patient is diagnosed as HIV-2-positive
    C. Results are inconclusive
    D. Patient is diagnosed as HIV-1-negative

Answer 20

C. Results are inconclusive

Question 21

21. A woman who has been pregnant for 12 weeks is
    tested for toxoplasmosis. Her IgM ELISA titer is
    2.6 (reference range < 1.6), and her IgG ELISA
    value is 66 (reference range < 8). The physician
    asks you if these results indicated an infection
    during the past 12 weeks. Which of the following
    tests would you recommend to determine if the
    woman was infected during her pregnancy?
    A. Toxo PCR on amniotic fluid
    B. Toxo IgM on amniotic fluid
    C. Toxo IgG avidity
    D. Amniotic fluid culture

Answer 21

C. Toxo IgG avidity

Question 22

22. On January 4, a serum protein electrophoresis on
    a specimen obtained at your hospital in North
    Dakota from a 58-year-old patient shows a band
    at the β-γ junction. The specimen was also
    positive for rheumatoid factor. You recommend
    that an immunofixation test be performed to
    determine if the band represents a monoclonal
    immunoglobulin. Another specimen is obtained
    2 weeks later by the physician in his office
    30 miles away, and the whole blood is submitted
    to you for the IFE. The courier placed the whole
    blood specimen in an ice chest for transport. In
    this specimen, no β-γ band is seen in the serum
    protein lane, and the IgM lane is very faint. The
    rheumatoid factor on this specimen was negative.
    The physician wants to know what’s wrong with
    your laboratory. Your response is:
    A. Nothing’s wrong with our laboratory; the patient
    had an infection 2 weeks ago that has cleared up
    B. Something’s wrong with our laboratory—we
    likely mislabeled one of the specimens; please
    resubmit a new specimen and we will test it at
    no charge
    C. You will run a second specimen using a
    2-mercaptoethanol treatment that will
    eliminate IgM aggregates and allow for
    more sensitive monoclonal IgM detection
    D. The physician should redraw another specimen
    from the patient and this time separate the serum
    from the clot in his office before sending the
    specimen in by courier

Answer 22

D. The physician should redraw another specimen
from the patient and this time separate the serum
from the clot in his office before sending the
specimen in by courier

Question 23

23. A dialysis patient is positive for both hepatitis B
    surface antigen and hepatitis B surface antibody.
    The physician suspects a laboratory error. Do you
    agree?
    A. Yes; the patient should not test positive for both
    HBsAg and HBsAb
    B. No; incomplete dialysis of a patient in the core
    window phase of hepatitis B infection will yield
    this result
    C. No; it is likely the patient has recently received a
    hepatitis B booster vaccination and could have
    these results
    D. Perhaps; a new specimen should be submitted to
    clear up the confusion

Answer 23

C. No; it is likely the patient has recently received a
hepatitis B booster vaccination and could have
these results

Question 24

24. You are evaluating an ELISA assay as a replacement
    for your immunofluorescent antinuclear antibody
    test. You test 50 specimens in duplicate on each
    assay. The ELISA assay uses a HEp-2 extract as its
    antigen source. The correlation between the ELISA
    and the IFA tests is only 60% (30 of 50 specimens
    agree). Which of the following is the next best
    course of action?
    A. Test another 50 specimens
    B. Perform a competency check on the
    technologists who performed the tests
    C. Order a new lot of both kits and then retest on
    the new lots
    D. Refer the discrepant specimens for testing by
    another method

Answer 24

D. Refer the discrepant specimens for testing by
another method