Harr’s Medical Laboratory Science Review PART (CHAPTER REVIEW) Flashcards by Toni Mae Inductivo

From the following, identify a specific component of the adaptive immune system that is formed in response to antigenic stimulation:

A. Lysozyme
B. Complement
C. Commensal organisms
D. Immunoglobulin (Ig)

D. Immunoglobulin (Ig)

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Which two organs are considered the primary lymphoid organs in which immunocompetent cells originate and mature?

A. Thyroid and Peyer patches
B. Thymus and bone marrow
C. Spleen and mucosal-associated lymphoid tissue (MALT)
D. Lymph nodes and thoracic duct

B. Thymus and bone marrow

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What type of B cells is formed after antigen stimulation?

A. Plasma cells and memory B cells
B. Mature B cells
C. Antigen-dependent B cells
D. Receptor-activated B cells

A. Plasma cells and memory B cells

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T cells travel from bone marrow to the thymus for maturation. What is the correct order of the maturation sequence for T cells in the thymus?

A. Bone marrow to the cortex; after thymic education, released back to peripheral circulation
B. Maturation and selection occur in the cortex; migration to the medulla; release of mature T cells to secondary lymphoid organs
C. Storage in either the cortex or medulla; release of T cells into the peripheral circulation
D. Activation and selection occur in the medulla; mature T cells are stored in the cortex until activated by antigen

B. Maturation and selection occur in the cortex; migration to the medulla; release of mature T cells to secondary lymphoid
organs

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Which cluster of differentiation (CD) marker is the most specific identifying marker for mature T cells?

A. CD1
B. CD2
C. CD3
D. CD4 or CD8

C. CD3

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Which markers are found on mature, peripheral helper T cells?

A. CD1, CD2, CD4
B. CD2, CD3, CD8
C. CD1, CD3, CD4
D. CD2, CD3, CD4

D. CD2, CD3, CD4

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Which T cells express the CD8 marker and act specifically to kill tumors or virally infected cells?

A. Helper T cells
B. Suppressor T cells
C. Cytotoxic T cells (TC cells)
D. Regulator T cells

C. Cytotoxic T cells (TC cells)

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How are TC cells and natural killer (NK) cells similar?

A. Require antibody to be present
B. Effective against virally infected cells
C. Recognize antigen in association with human leukocyte
antigen (HLA) class II markers
D. Do not bind to infected cells

B. Effective against virally infected cells

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What is the name of the process by which phagocytic cells are attracted to a substance, such as a bacterial peptide?

A. Diapedesis
B. Degranulation
C. Chemotaxis
D. Phagotaxis

C. Chemotaxis

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All of the following are immunologic functions of complement except:

A. Induction of an antiviral state
B. Opsonization
C. Chemotaxis
D. Anaphylatoxin formation

A. Induction of an antiviral state

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Which complement component is found in both the classic and alternative pathways?

A. C1
B. C4
C. Factor D
D. C3

D. C3

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Which region of the Ig molecule can bind antigen?

A. Fragment antigen binding (Fab)
B. Fragment crystallizable (Fc)
C. Constant light (CL)
D. Constant heavy (CH)

A. Fragment antigen binding (Fab)

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Which Ig(s) help(s) initiate the classic complement pathway?

A. IgA and IgD
B. IgM only
C. IgG and IgM
D. IgG only

C. IgG and IgM

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How is complement activity destroyed in vitro?

A. Heating serum at 56°C for 30 minutes
B. Keeping serum at room temperature of 22°C for 1 hour
C. Heating serum at 37°C for 45 minutes
D. Freezing serum at 0°C for 24 hours

A. Heating serum at 56°C for 30 minutes

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What is the purpose of C3a, C4a, and C5a, the split products of the complement cascade?

A. To bind with specific membrane receptors of lymphocytes and cause release of cytotoxic substances
B. To cause increased vascular permeability, contraction of smooth muscle, and release of histamine from basophils
C. To bind with membrane receptors of macrophages to facilitate phagocytosis and the removal of debris and foreign
substances
D. To regulate and degrade membrane cofactor protein after activation by C3 convertase

B. To cause increased vascular permeability, contraction of smooth muscle, and release of histamine from basophils

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Which region determines whether an Ig molecule can fix complement?

A. Variable heavy (VH)
B. Constant heavy (CH)
C. Variable light (VL)
D. Constant light (CL)

B. Constant heavy (CH)

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Which Ig class(es) has (have) a J-chain?

A. IgM
B. IgE and IgD
C. IgM and surface IgA (sIgA)
D. IgG3 and IgA

C. IgM and surface IgA (sIgA)

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Which Ig appears first in the primary immune response?

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

B. IgM

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Which immunoglobulin appears in highest titer in the secondary response?

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

A. IgG

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Which Ig can cross the placenta?

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

A. IgG

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Which Ig cross-links mast cells to release histamine?

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

D. IgE

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Which of the following cell surface molecules is classified as an MHC class II antigen?

A. HLA-A
B. HLA-B
C. HLA-C
D. HLA-DR

D. HLA-DR

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All of the following are functions of Igs except:

A. Neutralizing toxic substances
B. Facilitating phagocytosis through opsonization
C. Interacting with TC cells to lyse viruses
D. Combining with complement to destroy cellular antigens

C. Interacting with TC cells to lyse viruses

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Which of the following are products of HLA class III genes?

A. T-cell immune receptors
B. HLA-D antigens on immune cells
C. Complement proteins C2, C4, and factor B
D. Ig VL regions

C. Complement proteins C2, C4, and factor B

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24. Which MHC class of molecule is necessary for antigen recognition by CD4-positive T cells? A. Class I B. Class II C. Class III D. No MHC molecule is necessary for antigen recognition

B. Class II

28. Toll-like receptors (TLRs) are found on which cells? A. T cells B. Dendritic cells C. B cells D. Large granular lymphocytes

B. Dendritic cells

26. What molecule on the surface of most T cells recognizes antigen? A. IgT, a four-chain molecule that includes the tau heavy chain B. MHC protein, a two-chain molecule encoded by the HLA region C. CD3, consisting of six different chains D. T-cell receptor (TcR), consisting of two chains: α-chain and β-chain

D. T-cell receptor (TcR), consisting of two chains: α-chain and β-chain

27. TcR is similar to Ig molecules in that it: A. Remains bound to the cell surface and is never secreted B. Contains V and C regions on each of its chains C. Binds complement D. Can cross the placenta and provide protection to a fetus

B. Contains V and C regions on each of its chains

29. Macrophages produce which of the following proteins during antigen processing? A. IL-1 and IL-6 B. γ-Interferon C. IL-4, IL-5, and IL-10 D. Complement components C1 and C3

A. IL-1 and IL-6

30. A superantigen, such as toxic shock syndrome toxin-1 (TSST-1), bypasses the normal antigen-processing stage by binding to and cross-linking: A. A portion of an Ig molecule and complement component C1 B. TLRs and an MHC class 1 molecule C. A portion of an Ig and a portion of a TcR D. A portion of a TcR and an MHC class II molecule

D. A portion of a TcR and an MHC class II molecule

31. T-regulator cells, responsible for controlling autoimmune antibody production, express which of the following phenotypes? A. CD3, CD4, CD8 B. CD3, CD8, CD25 C. CD3, CD4, CD25 D. CD8, CD25, CD56

C. CD3, CD4, CD25

1. The interaction between individual antigen and antibody molecules depends on several types of bonds, such as ionic bonds, hydrogen bonds, hydrophobic bonds, and van der Waals forces. How is the strength of this attraction characterized? A. Avidity B. Affinity C. Reactivity D. Valency

B. Affinity

2. A laboratory is evaluating an enzyme-linked immunosorbent assay (ELISA) for detecting an antibody to cyclic citrullinated peptide (CCP), which is a marker for rheumatoid arthritis (RA). The laboratory includes serum from healthy volunteers and from patients with other connective tissue diseases in the evaluation. These specimens determine which factor of the assay? A. Sensitivity B. Precision C. Bias D. Specificity

D. Specificity

3. The detection of precipitation reactions depends on the presence of optimal proportions of antigen and antibody. A patient’s sample contains a large amount of antibody, but the reaction in a test system containing antigen is negative. What has happened? A. Performance error B. Low specificity C. A shift in the zone of equivalence D. Prozone phenomenon

D. Prozone phenomenon

4. The positive and negative control values for an ELISA procedure are below their acceptable ranges. What is the most likely cause? A. Decay of the positive and negative controls B. Incomplete washing following specimen addition C. Overly long incubation times D. Decay of the antibody–enzyme conjugate

D. Decay of the antibody–enzyme conjugate

5. What is the interpretation when an Ouchterlony plate shows crossed lines between wells 1 and 2 (antigen is placed in the center well and antisera in wells 1 and 2)? A. No reaction between wells 1 and 2 B. Partial identity between wells 1 and 2 C. Nonidentity between wells 1 and 2 D. Identity between wells 1 and 2

C. Nonidentity between wells 1 and 2

6. A weightlifter taking many supplements is tested monthly for thyroid-stimulating hormone (TSH) in a direct capture assay, which uses a streptavidin–biotin indicator system. She has had normal TSH levels for the past 3 months on specimens collected in the late evening. This month she comes in right after breakfast for her blood draw. The TSH level is three times her previous level. What may be the cause of this difference? A. Diurnal variation in TSH levels B. Exogenous biotin in her system from a supplement taken that morning C. Reduced thyroid function caused by an unidentified pathology D. Pipetting error

B. Exogenous biotin in her system from a supplement taken that morning

7. What comprises the indicator system in an indirect ELISA for detecting antibody? A. Enzyme-conjugated antibody + chromogenic substrate B. Enzyme conjugated antigen + chromogenic substrate C. Enzyme + antigen D. Substrate + antigen

A. Enzyme-conjugated antibody + chromogenic substrate

8. What outcome results from improper washing of a tube or well after adding the enzyme–antibody conjugate in an ELISA system? A. Result will be falsely decreased B. Result will be falsely increased C. Result will be unaffected D. Result is impossible to determine

B. Result will be falsely increased

9. What would happen if the color reaction phase is prolonged in one tube or well of an ELISA test? A. Result will be falsely decreased B. Result will be falsely increased C. Result will be unaffected D. Impossible to determine

B. Result will be falsely increased

10. The absorbance of a sample measured by ELISA is greater than the highest standard. What corrective action should be taken? A. Extrapolate an estimated value from the highest reading B. Repeat the test using a standard of higher concentration C. Repeat the assay using one half the volume of the sample D. Dilute the test sample

D. Dilute the test sample

11. A patient was suspected of having a lymphoproliferative disorder. After several laboratory tests were completed, the patient was found to have an IgMκ paraprotein. In what sequence should the laboratory tests leading to this diagnosis have been performed? A. Serum protein electrophoresis (SPE) followed by immunofixation electrophoresis (IFE) B. Ig levels, followed by SPE C. Total lymphocyte count, followed by Ig levels D. Ig levels, followed by urine protein electrophoresis

A. Serum protein electrophoresis (SPE) followed by immunofixation electrophoresis (IFE)

12. An IFE performed on a serum sample showed a narrow dark band in the lanes containing anti-γ and anti-λ. How should this result be interpreted? A. Abnormally decreased IgG concentration B. Abnormal test result demonstrating monoclonal IgGλ C. Normal test result D. Impossible to determine without densitometric quantitation

B. Abnormal test result demonstrating monoclonal IgGλ

13. Which type of nephelometry is used to measure immune complex formation almost immediately after reagent has been added? A. Rate B. Endpoint C. Continuous D. One-dimensional

A. Rate

14. An antinuclear antibody (ANA) test was performed by using immunofluorescence microscopy assay (IFA), and a clinically significant pattern and titer were reported. Positive and negative controls performed as expected. However, the clinical evaluation of the patient was not consistent with the reported pattern. What is the most likely explanation for this situation? A. The clinical condition of the patient changed since the sample was tested B. The pattern of fluorescence was misinterpreted C. The control results were misinterpreted D. The wrong cell line was used for the test

B. The pattern of fluorescence was misinterpreted

15. What corrective action should be taken when a specific pattern cannot be identified in a specimen with a positive ANA IFA? A. Repeat the test using a larger volume of sample B. Call the physician C. Have another medical laboratory scientist read the slide D. Dilute the sample and retest

D. Dilute the sample and retest

16. Which statement best describes passive agglutination reactions used for serodiagnosis? A. Such agglutination reactions are more rapid because they are a single-step process B. Reactions require the addition of a second antibody C. Passive agglutination reactions require biphasic incubation D. Carrier particles for antigen, such as latex particles, are used

D. Carrier particles for antigen, such as latex particles, are used

17. What has happened in a titer, if tube Nos. 5 to 7 show a stronger reaction than tube Nos.1 to 4? A. Prozone reaction B. Postzone reaction C. Equivalence reaction D. Poor technique

A. Prozone reaction

18. What is the titer in tube No. 8 if tube No. 1 is undiluted and dilutions are doubled? A. 64 B. 128 C. 256 D. 512

B. 128

19. The directions for a slide agglutination test instruct that after mixing the patient’s serum and antigen-coated latex particles, the slide must be rotated for 2 minutes. What would happen if the slide were rotated for 10 minutes? A. Possible false-positive result B. Possible false-negative result C. No effect D. Depends on the amount of antibody present in the sample

A. Possible false-positive result

20. Which outcome indicates a negative result in a complement fixation test? A. Hemagglutination B. Absence of hemagglutination C. Hemolysis D. Absence of hemolysis

C. Hemolysis

22. Which statement best describes immunophenotyping? A. Lineage determination by detecting antigens on the surface of the gated cells by using fluorescent antibodies B. Identification of cell maturity by using antibodies to detect antigens within the nucleus C. Identification and sorting of cells by front and side scatter of light from a laser D. Analysis of cells collected by flow cytometry by using traditional agglutination reactions

A. Lineage determination by detecting antigens on the surface of the gated cells by using fluorescent antibodies

23. A flow cytometry scattergram of a bone marrow sample shows a dense population of cells located in-between normal lymphoid and normal myeloid cells. What is the most likely explanation? A. The sample was improperly collected B. An abnormal cell population is present C. The laser optics are out of alignment D. The cells are most likely not leukocytes

B. An abnormal cell population is present

1. Which serum antibody response usually characterizes the primary (early) stage of syphilis? A. Antibodies against syphilis are undetectable B. Detected 1 to 3 weeks after appearance of the primary chancre C. Detected in 50% of cases before the primary chancre disappears D. Detected within 2 weeks after infection

B. Detected 1 to 3 weeks after appearance of the primary chancre

2. What substance is detected in the sample by the rapid plasma Reagin (RPR) and Venereal Disease Research Laboratory (VDRL) tests for syphilis? A. Cardiolipin B. Anticardiolipin antibody (ACA) C. Anti–Treponema pallidum antibody D. T. pallidum

B. Anticardiolipin antibody (ACA)

3. What type of antigen is used in the RPR card test? A. Live treponemal organisms B. Killed suspension of treponemal organisms C. Cardiolipin D. Tanned sheep cells

C. Cardiolipin

4. Which of the following is the most sensitive test to detect congenital syphilis? A. VDRL B. RPR C. T. pallidum particle agglutination (TP-PA) D. Polymerase chain reaction (PCR)

D. Polymerase chain reaction (PCR)

7. Which test is most likely to be positive in the tertiary stage of syphilis? A. Treponemal-specific antibody B. RPR C. VDRL D. Reagin screen test (RST)

A. Treponemal-specific antibody

5. A biological false-positive reaction is least likely with which test for syphilis? A. VDRL B. TP-PA C. RPR D. All are equally likely to yield a false-positive result

B. TP-PA

6. A 12-year old girl has symptoms of fatigue and localized lymphadenopathy. Laboratory tests reveal peripheral blood lymphocytosis, positive RPR, and positive spot test for IM. What test should be performed next? A. HIV screen B. VDRL C. Epstein-Barr virus (EBV)–specific antigen test D. TP-PA test

D. TP-PA test

9. Which specimen is the sample of choice to evaluate latent or tertiary syphilis? A. Serum sample B. Chancre fluid C. Cerebrospinal fluid (CSF) D. Joint fluid

C. Cerebrospinal fluid (CSF)

11. Tests to identify infection with HIV fall into which three general classification types of tests? A. Tissue culture, antigen, and antibody tests B. Tests for antigens, antibodies, and nucleic acid C. DNA probe, DNA amplification, and Western blot tests D. ELISA, Western blot, and Southern blot tests

B. Tests for antigens, antibodies, and nucleic acid

10. Interpret the following quantitative RPR test results RPR titer: weakly reactive—1:4; reactive—1:8 to 1:64 A. Excess antibody, prozone effect B. Excess antigen, postzone effect C. Equivalence of antigen and antibody D. Impossible to interpret, testing error

A. Excess antibody, prozone effect

8. What is the most likely interpretation of the following syphilis serological results? RPR: reactive; TP-PA: nonreactive A. Neurosyphilis B. Secondary syphilis C. Syphilis that has been successfully treated D. Biological false positive

D. Biological false positive

12. Which tests are considered screening tests for HIV? A. ELISA, chemiluminescent, and rapid antibody tests B. IFA, Western blot, radioimmunoprecipitation assay C. Culture, antigen capture assay, DNA amplification D. Reverse transcriptase and messenger RNA (mRNA) assay

A. ELISA, chemiluminescent, and rapid antibody tests

13. Which tests are the recommended confirmatory tests for HIV? A. ELISA and rapid antibody tests B. HIV-1,2 antibody differentiation assays, and qualitative PCR test C. Culture, antigen capture assay, quantitative PCR D. Reverse transcriptase and mRNA assay

B. HIV-1,2 antibody differentiation assays, and qualitative PCR test

17. What is the most likely explanation when antibody tests for HIV are negative but the PCR test is positive? A. Probably not HIV infection B. Patient is in the “window phase” before antibody production C. Tests were performed incorrectly D. Clinical signs may be misinterpreted

B. Patient is in the “window phase” before antibody production

16. Interpret the following results for HIV testing Fourth-generation ELISA: positive; Repeat ELISA: positive; HIV 1,2 antibody differentiation assay: negative; Qualitative HIV RNA rtPCR assay: positive A. False-positive fourth-generation assay B. False-negative antibody differentiation assay C. Indeterminate; further testing indicated D. HIV p24 antigen detected on fourth-generation ELISA

D. HIV p24 antigen detected on fourth-generation ELISA

14. How do fourth- and fifth-generation HIV tests reduce the time from infection to the test becoming positive? A. They are PCR tests detecting viral RNA B. They detect p24 antigen in addition to HIV antibody C. They detect proviral DNA D. They detect antibodies to more antigens than earlier generations of HIV tests

B. They detect p24 antigen in addition to HIV antibody

15. A woman who has had five pregnancies subsequently tests positive for HIV on a fourth generation assay and is negative on an HIV-1,2 differentiation assay and a follow-up molecular assay. The initial reactivity may be caused by: A. Possible cross-reaction with herpes or EBV antibodies B. Interference from medication C. Cross-reacting antibodies elicited during pregnancy D. Possible technical error; a repeat specimen should be requested

C. Cross-reacting antibodies elicited during pregnancy

18. What criteria constitute the classification system for HIV infection? A. CD4-positive T-cell count and clinical symptoms B. Clinical symptoms, condition, duration, and strength of reactivity on a fourth-generation HIV test C. Presence or absence of lymphadenopathy D. Strong fourth-generation HIV test reactivity and CD8-positive T-cell count

A. CD4-positive T-cell count and clinical symptoms

19. What is the main difficulty associated with the development of an HIV vaccine? A. The virus has been difficult to culture; antigen extraction and concentration are extremely laborious B. Human trials cannot be performed C. Different strains of the virus are genetically diverse D. Anti-idiotype antibodies cannot be developed

C. Different strains of the virus are genetically diverse

21. What is the advantage of fourth-generation rapid HIV tests over earlier rapid HIV tests? A. They use recombinant antigens B. They detect multiple strains of HIV C. They detect p24 antigen D. They are quantitative

C. They detect p24 antigen

20. Which CD4:CD8 ratio is most likely in a patient with AIDS? A. 2:1 B. 3:1 C. 2:3 D. 1:3

D. 1:3

23. What is the most likely cause when a fourth-generation HIV assay is positive for all controls and samples? A. Improper pipetting B. Improper washing C. Improper addition of sample D. Improper reading

B. Improper washing

22. Which method is used to test for HIV infection in infants who are born to HIV-positive mothers? A. ELISA B. Western blot test C. PCR test D. Viral culture

C. PCR test

24. What constitutes a diagnosis of viral hepatitis? A. Abnormal test results for liver enzymes B. Clinical signs and symptoms C. Positive results for hepatitis markers D. All of these options

D. All of these options

25. Which of the following statements regarding infection with hepatitis D virus (HDV) is true? A. Occurs in patients with HIV infection B. Does not progress to chronic hepatitis C. Occurs in patients with hepatitis B virus (HBV) infection D. Is not spread through blood or sexual contact

C. Occurs in patients with hepatitis B virus (HBV) infection

26. All of the following hepatitis viruses are spread through blood or blood products except: A. Hepatitis A virus (HAV) B. HBV C. HCV D. HDV

A. Hepatitis A virus (HAV)

27. Which hepatitis B marker is the best indicator of early acute infection? A. Hepatitis B surface antigen (HBsAg) B. Hepatitis B e-antigen (HBeAg) C. Hepatitis B core antibody (anti-HBc) D. Hepatitis B surface antibody (anti-HBs)

A. Hepatitis B surface antigen (HBsAg)

28. Which is the first antibody detected in serum after infection with HBV? A. Anti-HBs B. Anti-HBc IgM C. Anti-HBe D. All are detectable at the same time

B. Anti-HBc IgM

29. Which antibody persists in low-level carriers of HBV? A. IgM anti-HBc B. IgG anti-HBc C. IgM anti-HBe D. IgG anti-HBs

B. IgG anti-HBc

31. Which hepatitis B markers should be performed on blood products? A. HBsAg and anti-HBc B. Anti-HBs and anti-HBc C. HBeAg and HBcAg D. Anti-HBs and HBeAg

A. HBsAg and anti-HBc

30. What is the most likely explanation when a patient has clinical signs of viral hepatitis but tests negative for HAV IgM, HBsAg, and HCV antibody? A. Tests were performed improperly B. The patient does not have hepatitis C. The patient may be in the “core window” D. Clinical evaluation was performed improperly

C. The patient may be in the “core window”

32. Which hepatitis antibody confers immunity against reinfection with HBV? A. Anti-HBc IgM B. Anti-HBc IgG C. Anti-HBe D. Anti-HBs

D. Anti-HBs

33. Which test, other than serological markers, is most consistently elevated in viral hepatitis? A. Antinuclear antibodies B. Alanine aminotransferase (ALT) C. Absolute lymphocyte count D. Lactate dehydrogenase

B. Alanine aminotransferase (ALT)

34. If only anti-HBs is positive, which of the following can be ruled out? A. HBV vaccination B. Distant past infection with HBV C. Hepatitis B immune globulin (HBIG) injection D. Chronic HBV infection

D. Chronic HBV infection

35. Interpret the following results for EBV infection: IgG and IgM antibodies to viral capsid antigen (VCA) are positive. A. Infection in the past B. Infection with a mutual enhancer virus, such as HIV C. Current infection D. Impossible to interpret; need more information

C. Current infection

36. Rapid mono tests use latex particles coated with which of the following? A. Guinea pig antigen B. Beef proteins C. Horse proteins D. Sheep proteins

B. Beef proteins

37. Blood products are tested for which virus before being transfused to newborns? A. EBV B. Human T-lymphotropic virus II (HTLV-II) C. CMV D. HDV

C. CMV

38. What is the endpoint for the antistreptolysin O (ASO) latex agglutination assay? A. Highest serum dilution that shows no agglutination B. Highest serum dilution that shows agglutination C. Lowest serum dilution that shows agglutination D. Lowest serum dilution that shows no agglutination

B. Highest serum dilution that shows agglutination

39. A streptozyme test was performed, but the result was negative, even though the patient showed clinical signs of a streptococcal throat infection. What should be done next? A. Either ASO or anti-deoxyribonuclease B (anti-DNase B) test B. Another streptozyme test using diluted serum C. Antihyaluronidase test D. Wait for 3 to 5 days and repeat the streptozyme test

A. Either ASO or anti-deoxyribonuclease B (anti-DNase B) test

40. Rapid assays for influenza that utilize specimens obtained from nasopharyngeal swabs detect: A. IgM anti-influenza B. IgA anti-influenza C. IgA–influenza antigen immune complexes D. Influenza nucleoprotein antigens

D. Influenza nucleoprotein antigens

41. How can interfering cold agglutinins be removed from a test sample? A. Centrifuge the serum and remove the top layer B. Incubate the clot at 1°C to 4°C for several hours and then remove the serum C. Incubate the serum at 56°C in a water bath for 30 minutes D. Use an anticoagulated sample

B. Incubate the clot at 1°C to 4°C for several hours and then remove the serum

42. All tubes (dilutions) except the negative control are positive for cold agglutinins. This indicates: A. Contaminated RBCs B. A rare antibody against RBC antigens C. The sample was stored at 4°C prior to separating serum and cells D. Further serial dilution is necessary

D. Further serial dilution is necessary

45. Which of the following positive antibody tests may be an indication of recent vaccination or early primary infection for rubella in a patient with no clinical symptoms? A. Only IgG antibodies positive B. Only IgM antibodies positive C. Both IgG and IgM antibodies positive D. Fourfold rise in titer for IgG antibodies

B. Only IgM antibodies positive

43. All positive cold agglutinin tubes remain positive after 37°C incubation except the positive control. What is the most likely explanation for this situation? A. High-titer cold agglutinins B. Contamination of the test system C. Antibody other than cold agglutinins D. Faulty water bath

C. Antibody other than cold agglutinins

46. Why is laboratory diagnosis difficult in cases of Lyme disease? A. Clinical response may not be apparent upon initial infection; IgM antibody may not be detected until 3 to 6 weeks after the infection B. Laboratory tests may be designed to detect whole Borrelia burgdorferi, not flagellar antigen found early in infection C. Most laboratory tests are technically demanding and lacks specificity D. Antibodies formed initially to B. burgdorferi may cross react in antigen tests for autoimmune diseases

A. Clinical response may not be apparent upon initial infection; IgM antibody may not be detected until 3 to 6 weeks after the infection

44. Which increase in antibody titer (dilution) best indicates an acute infection? A. From 1:2 to 1:8 B. From 1:4 to 1:16 C. From 1:16 to 1:256 D. From 1:64 to 1:128

C. From 1:16 to 1:256

47. Serological tests for which disease may give a false-positive result if the patient has Lyme disease? A. HIV B. Syphilis C. EBV D. Hepatitis C

B. Syphilis

48. In monitoring a patient with HIV infection, which parameter may be expected to be the most sensitive indicator of the effectiveness of antiretroviral treatment? A. HIV antibody titer B. CD4:CD8 ratio C. HIV viral load D. Absolute total T-cell count

C. HIV viral load

49. A renal transplant recipient is found to have a rising creatinine level and reduced urine output. The physician orders a “urine PCR” assay. When you call to find out what organism the physician wants to identify, you are told: A. HCV B. Legionella pneumophila C. EBV D. BK virus

D. BK virus

50. A newborn is to be tested for vertically transmitted HIV infection. Which of the following tests is most useful? A. HIV PCR B. CD4 count C. Rapid HIV antibody test D. HIV IgM antibody test

A. HIV PCR

51. Which of the following fungal organisms is best diagnosed by an antigen detection test as opposed to an antibody detection assay? A. Histoplasma B. Cryptococcus C. Candida D. Aspergillus

B. Cryptococcus

52. Your cytology laboratory refers a Papanicolaou smear specimen to you for an assay designed to detect the presence of a virus associated with cervical cancer. You perform: A. An ELISA for anti-human simplex virus 2 (anti-HSV-2) antibodies B. A molecular assay for HSV-2 C. An ELISA for human papilloma virus (HPV) antibodies D. A molecular assay for HPV

D. A molecular assay for HPV

53. An immunosuppressed patient has unexplained anemia. The physician suspects a parvovirus B19 infection. The parvovirus IgM test result is negative. The next course of action is to tell the physician that: A. The patient does not have parvovirus B. A convalescent specimen is recommended in 4 weeks to determine if a fourfold rise in titer has occurred C. A parvovirus PCR is recommended D. A recent transfusion for the patient’s anemia may have resulted in a false-negative result and the patient should be retested in 4 weeks

C. A parvovirus PCR is recommended