SEROLOGY Flashcards by Danzel Matthew Nava

Color Plate 21 depicts a monomeric
immunoglobulin molecule. The portion of the
molecule indicated by the dotted red circle and
the red arrow is called the
A. Fab fragment
B. Fc fragment
C. Heavy chain
D. Hinge region

A. Fab fragment

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Ahaptenis
A. Half of an immunoglobulin molecule
B. A earner molecule for an antigen that
is not antigenic alone
C. An immunoglobulin functional only in
the presence of complement
D. A determinant capable of stimulating
an immune response only when bound
to a carrier

D. A determinant capable of stimulating
an immune response only when bound
to a carrier

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Which of the following is characteristic of
B cells?
A. Phagocytic
B. Participate in antibody-dependent
cellular cytotoxicity (ADCC) reactions
C. Contain surface immunoglobulins
D. Secrete the C5 component of
complement

C. Contain surface immunoglobulins

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A lymphokine is
A. A soluble mediator produced by
granulocytes and affecting lymphocytes
B. A soluble mediator produced by
lymphocytes
C. A soluble mediator produced by
plasma cells
D. An antibody that reacts with
lymphocytes

B. A soluble mediator produced by
lymphocytes

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Monocytes and macrophages play a major
role in the mononuclear phagocytic
system. For an antibody-coated antigen to
be phagocytized, what part of the antibody
molecule fits into a receptor on the
phagocytic cell?
A. Fc region
B. Fab region
C. Hinge region
D. Variable region

A. Fc region

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Cell-mediated immunity is primarily
mediated by
A. B cells
B. T helper cells
C. Plasma cells
D. Dendritic cells

B. T helper cells

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The HLA complex is located primarily on
A. Chromosomes
B. Chromosome 6
C. Chromosome 9
D. Chromosome 17

B. Chromosome 6

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HLA antigens are found on
A. All nucleated cells
B. Red blood cells only
C. Solid tissue only
D. White blood cells only

A. All nucleated cells

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Which of the following is more likely to
be diagnostic of an acute infection?
A. A total acute antibody liter of 2
followed by a convalescent titer of 16
B. A total acute antibody titer of 80
followed by a convalescent titer of 40
C. A total antibody titer of 80
D. An IgG antibody titer of 80

A. A total acute antibody liter of 2
followed by a convalescent titer of 16

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A young woman shows increased
susceptibility to pyogenic infections.
Upon assay, she shows a low level of C3.
Which of the following statements is
probably true?
A. She has an autoimmune disease with
continual antigen-antibody activity
causing consumption of C3.
B. She has DiGeorge syndrome.
C. She has decreased production of C3.
D. She may produce an inactive form of
C2, a precursor of C3

C. She has decreased production of C3.

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What is the predominant type of antibody
found in the serum of neonates born after
full-term gestation?
A. Infant IgA
B. Infant IgG
C. Infant IgM
D. Maternal IgG

D. Maternal IgG

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An important part of the nonspecific
immune response is(are)
A. B cells
B. Basophils
C. Complement cascade
D. Cytotoxic T lymphocytes

C. Complement cascade

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The major class of immunoglobulin found
in adult human serum is
A. IgA
B. IgE
C. IgG
D. IgM

C. IgG

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Which class of immunoglobulin possesses
delta heavy chains?
A. IgA
B. IgD
C. IgE
D. IgG

B. IgD

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Which class of immunoglobulin possesses
10 antigenic binding sites?
A. IgA
B. IgD
C. IgG
D. IgM

D. IgM

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Color Plate 22 * represents a dimeric IgA
molecule. The structure printed in red and
indicated by the red arrow is called the

A. J-piece
B. Hinge region
C. Heavy chain
D. Light chain

A. J-piece

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Which class of immunoglobulin binds to
basophils and mast cells to mediate
immediate hypersensitivity reactions?
A. IgA
B. IgD
C. IgE
D. IgG

C. IgE

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Type I hypersensitivity is
A. Associated with complement-mediated cell lysis
B. Due to immune complex deposition
C. Mediated by activated macrophages
D. An immediate allergic reaction

D. An immediate allergic reaction

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When performing the enzyme-multiplied
immunoassay technique (EMIT), how is
the ligand in the patient’s serum detected?

A. Agglutinates by binding to antibody-coated latex beads
B. Binds to enzyme-labeled antibody
C. Competes with enzyme-labeled
antigen for binding to a specific
antibody
D. Forms antibody-antigen complex and
precipitates

C. Competes with enzyme-labeled
antigen for binding to a specific
antibody

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Severe combined immunodeficiency
(SCID) is an

A. Immunodeficiency with decreased B
cells and neutrophils
B. Immunodeficiency with lymphocytopenia and eosinophilia
C. Immunodeficiency with decreased or
dysfunctional T and B cells
D. Immunodeficiency with decreased
lymphocytes and decreased complement concentration

C. Immunodeficiency with decreased or
dysfunctional T and B cells

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An example of immune injury due to the
deposition of antigen-antibody complexes is

A. Acute glomerulonephritis
B. Bee-sting allergy
C. Contact dermatitis
D. Penicillin allergy

A. Acute glomerulonephritis

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The serologically detectable antibody
produced in rheumatoid arthritis (RA) is
primarily of the class
A. IgA
B. IgE
C. IgG
D. IgM

D. IgM

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In bone marrow transplantation, immuno-competent cells in the donor marrow may recognize antigens in the recipient and
respond to those antigens. This phenomenon is an example of
A. Acute rejection
B. Chronic rejection
C. Graft versus host disease
D. Hyperacute rejection

C. Graft versus host disease

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Multiple myeloma is a

A. Lymphoproliferative disease of T cells
B. Cancer of plasma cells characterized
by increased antibody concentration
C. Lymphoproliferative disease resulting
in a decrease in antibody production
D. Cancer of monocytes characterized by
increased kappa and lambda chain
synthesis

B. Cancer of plasma cells characterized
by increased antibody concentration

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25. Which one of the following describes a direct immunofluorescence assay? A. Conjugated reagent antigen reacts with antibodies to form antigen-antibody complexes B. Antigens react with unlabeled antibody-forming antigen-antibody complexes that attach to labeled antibodies C. A dye is attached to a molecule and it reacts with an immune complex to produce a color D. Conjugated reagent antibody reacts with antigen to form antigen-antibody complexes

D. Conjugated reagent antibody reacts with antigen to form antigen-antibody complexes

26. In individuals allergic to pollen, hyposensitization protocols may be initiated. These individuals receive injections of A. Allergen B. Pooled human antisera C. Monoclonal antibody directed against human T cells D. Monoclonal antibody directed against human B cells

A. Allergen

27. After exposure to antigen, the first antibodies that can be detected belong to the class A. IgA B. IgE C. IgG D. IgM

D. IgM

28. Corneal tissue may be transplanted successfully from one patient to another because A. The cornea is nonantigenic B. Cornea! antigens do not activate T cells C. Anticorneal antibodies are easily suppressed D. The cornea occupies a privileged site not usually seen by the immune system

D. The cornea occupies a privileged site not usually seen by the immune system

29. A kidney transplant from one identical twin to another is an example of a(n) A. Allograft B. Autograft C. Isograft D. Xenograft

C. Isograft

30. In Bruton disease, measurement of serum immunoglobulins would show A. Elevated levels of IgE B. Elevated levels of IgG C. Normal levels of IgG and IgM but reduced levels of IgA D. The absence of all immunoglobulins

D. The absence of all immunoglobulins

31. Diagnosis of group A streptococci (Streptococcus pyogenes) infection is indicated by the presence of A. Anti-protein A B. Anti-DNaseB C. Anti-beta-toxin D. C-reactive protein

B. Anti-DNaseB

32. A molecule found in human serum sometimes used as a tumor marker is A. a-Fetoprotein B. HBsAg C. Biotin D. GDI

A. a-Fetoprotein

33. Which cell is the principal source of interleukin 2? A. Bcell B. Tcell C. Monocyte D. Plasma cell

B. Tcell

34. Diagnostic reagents useful for detecting antigen by the coagglutination reaction may be prepared by binding antibody to killed staphylococcal cells via the Fc receptor of **staphylococcal protein A.** The class of antibody bound by this protein is A. IgA B. IgD C. IgG D. IgM

C. IgG

35. A major advantage of passive immunization compared to active immunization is that A. Antibody is available more quickly B. Antibody persists for the life of the recipient C. IgM is the predominant antibody class provided D. Oral administration can be used

A. Antibody is available more quickly

36. The strength with which a multivalent antibody binds a multivalent antigen is termed the A. Affinity B. Avidity C. Reactivity D. Valence

B. Avidity

37. How does the secondary humoral immune response differ from the primary response? A. The lag phase (the time between exposure to immunogen and production of antibody) is longer in the secondary immune response. B. IgM is the predominant antibody class produced in the secondary immune response. C. The antibody levels produced are higher in the secondary immune response. D. Cytotoxic T lymphocytes play an important role in the secondary response.

C. The antibody levels produced are higher in the secondary immune response.

38. After activation of the complement system, leukocytes and macrophages are attracted to the site of complement activation by A. Cl B. C5a C. C8 D. IgM

B. C5a

39. The type of immunity that follows the injection of an immunogen is termed A. Artificial active B. Natural active C. Artificial passive D. Innate

A. Artificial active

40. The type of immunity that follows the injection of antibodies synthesized by another individual or animal is termed A. Artificial active B. Natural adaptive C. Artificial passive D. Natural passive

C. Artificial passive

41. Innate immunity includes A. Anamnestic response B. Antibody production C. Cytotoxic T cell activity D. Phagocytosis by polymorphonuclear cells

D. Phagocytosis by polymorphonuclear cells

42. The agglutination pattern shown in Color Plate 23 * was observed while performing an antibody titration. This agglutination pattern is an example of A. A prezone reaction B. A prozone reaction C. A postzone reaction D. Incomplete complement inactivation

B. A prozone reaction

43. The antibody most frequently present in systemic lupus erythematosus is directed against A. Surface antigens of bone marrow stem cells B. Surface antigens of renal cells C. Nuclear antigen D. Myelin

C. Nuclear antigen

44. The rapid plasma reagin assay for syphilis does not need to be read microscopically because the antigen is A. Cardiolipin B. Complexed with latex C. Complexed with charcoal D. Inactivated bacterial cells

C. Complexed with charcoal

45. The Venereal Disease Research Laboratory (VDRL) test for syphilis is classified as a(n) A. Agglutination reaction B. Flocculation reaction C. Hemagglutination reaction D. Precipitation reaction

B. Flocculation reaction

46. One cause of a false-positive VDRL test is A. Brucellosis B. Treponema pallidum infection C. Rocky Mountain spotted fever D. Systemic lupus erythematosus

D. Systemic lupus erythematosus

47. The portion of an antigen that binds to an antibody or T cell receptor is called a(n) A. Allergin B. Avidin C. Epitope D. Valence

C. Epitope

48. Identical antibodies produced from a single clone of plasma cells describes A. Reagin B. Cold agglutinins C. Heterophile antibodies D. Monoclonal antibodies

d. Monoclonal antibodies

49. IgM antibodies react well in complement fixation (CF) tests. Because of this, CF tests for antibodies should A. Be positive early in the course of the disease B. Be useful in identifying antibodies responsible for a delayed hypersensitivity reaction C. Be useful in identifying antibodies responsible for anaphylactic reactions D. Detect transplacental antibodies

A. Be positive early in the course of the disease

50. Which of the following serologic tests is commonly performed by an immunofluorescence method? A. Anti-HBs B. Antinuclear antibody (ANA) C. Antistreptolysin O (ASO) D. C-reactive protein (CRP)

B. Antinuclear antibody (ANA)

51. The Fab portion of an antibody A. Binds T cell receptor B. Consists of two light chains only C. Consists of two heavy chains only D. Contains the hypervariable region

D. Contains the hypervariable region

52. In the enzyme-linked immunosorbent assay (ELISA), the visible reaction is due to a reaction between A. Enzyme and antibody B. Enzyme and substrate C. Fluorescent dye and antigen D. Latex particles and antibody

B. Enzyme and substrate

53. Elevated IgE levels are typically found in A. Type I hypersensitivity reactions B. Type II hypersensitivity reactions C. Type III hypersensitivity reactions D. Type IV hypersensitivity reactions

A. Type I hypersensitivity reactions

54. Loss of self-tolerance results in A. Autoimmune disease B. Graft-versus-host disease C. Immunodeficiency D. Tumors

A. Autoimmune disease

55. A human cell with CDS on its surface is most likely a A. Bcell B. Monocyte C. T helper cell D. Cytotoxic T cell

D. Cytotoxic T cell

56. Which of the following statements about immunoglobulin light chains is true ? A. Each immunoglobulin monomer has either one kappa or one lambda chain. B. There are two types: kappa and lambda. C. They consist of constant regions only. D. They form part of the Fc fragment

B. There are two types: kappa and lambda.

57. Which of the following statements applies to the Fc fragment of an immunoglobulin molecule? A. It consists of the entire heavy chain. B. It contains the variable region of the heavy chain. C. It contains the antigen binding sites of the molecule. D. It is the region of the molecule that binds to receptors on various white blood cells.

D. It is the region of the molecule that binds to receptors on various white blood cells.

58. Monoclonal antibodies are produced by A. Cultured T cells B. Human plasma cells C. Mouse plasma cells D. Hybridomas

D. Hybridomas

59. Antibodies that bind to the same epitope are of the same A. Allotype B. Autotype C. Idiotype D. Isotype

C. Idiotype

60. Skin testing is a useful diagnostic tool in a number of disorders, such as tuberculosis. Which of the following statements about skin testing is true? A. A positive test depends on preformed antibody. B. Reactivity to a particular antigen may be transferred from one individual to another by sensitized lymphocytes. C. The intensity of the response correlates directly with the clinical activity of the disease. D. The maximum response will occur immediately.

B. Reactivity to a particular antigen may be transferred from one individual to another by sensitized lymphocytes.

61. The activity of natural killer (NK) cells A. Does not require previous exposure to an antigen B. Involves phagocytosis and killing of bacteria C. Requires interaction with cytotoxic T cells D. Requires interaction with B cells

A. Does not require previous exposure to an antigen

62. Interaction between B and T helper cells involves A. MHC II molecule on B cell binding to MHCI molecule on the T cell B. MHC II molecule on B cell binding to CDS on the T cell C. Foreign antigen on B cell binding to T cell receptor D. CDS molecule on B cell binding to T cell receptor

C. Foreign antigen on B cell binding to T cell receptor

63. Which of the following is a characteristic of T cells? A. Synthesize antibody B. Mature in the thymus C. Able to bind unprocessed antigen D. Primarily protect against extracellular parasites

B. Mature in the thymus

64. The primary mechanism responsible for pathology in systemic lupus erythematosus is A. Allergic reaction to foreign molecules B. Antibodies directed against self antigens C. Polyclonal activation of cytotoxic T cells D. Lack of intracellular killing after neutrophil phagocytosis of bacteria

B. Antibodies directed against self antigens

65. Which complement protein is present in the greatest concentration in human serum? A. Cl B. C2 C. C3 D. C4

C. C3

66. An autoimmune disease causing the destruction of pancreatic cells can result in A. Hashimoto disease B. Multiple sclerosis C. My asthenia gravis D. Type 1 diabetes

D. Type 1 diabetes

67. An Ouchterlony gel diffusion plate is depicted in Color Plate 24B. The center well contains antibody, and the peripheral wells contain antigens labeled 1 through 4. What is the relationship between the antigens in wells 2 and 3? A. 2 is part of 3. B. 3 is part of 2. C. They are identical. D. They are unrelated.

D. They are unrelated.

68. An Ouchterlony gel diffusion plate is depicted in Color Plate 24B. The center well contains antibody, and the peripheral wells contain antigens labeled 1 through 4. What is the relationship between the antigens in wells 2 and 4? A. Cannot be determined. B. They are identical. C. They are unrelated. D. They react incompletely with the antibody.

B. They are identical.

69. Which of the following complement proteins is part of the membrane attack complex? A. Cl B. C3 C. C4 D. C5

D. C5

70. Which of the following is characteristic of contact hypersensitivity reactions? A. Caused by preformed IgE antibody B. Characterized by infiltration of neutrophils into the area of reaction C. The primary symptoms often occur in the respiratory tract. D. Usually due to a hapten

D. Usually due to a hapten

71. Which of the following statements about the test for C-reactive protein (CRP) is true? A. It correlates with neutrophil phagocytic function. B. It is an indicator of ongoing inflammation. C. It is diagnostic for rheumatic fever. D. Levels decrease during heart disease

B. It is an indicator of ongoing inflammation.

72. In the classical pathway of complement activation, A. C3 is activated by binding C-reactive protein B. The sequence of activation is Cl, C2, C3,C4 C. Clq is activated by the presence of a single Fab region D. Activation by antibody requires one IgM or two IgG molecules

D. Activation by antibody requires one IgM or two IgG molecules

73. The alternative complement pathway A. Can be activated by bacterial capsule polysaccharides B. Uses C5b as a C3 convertase C. Bypasses steps C3 through C5 D. Is inactivated by properdin

A. Can be activated by bacterial capsule polysaccharides

74. A cut on a person's finger becomes contaminated with the bacterium Staphylococcus aureus. The first response by the immune system consists of activity of A. B cells B. Monocytes C. Neutrophils D. T cells

C. Neutrophils

75. Incompatible blood transfusions are examples of A. Type I hypersensitivity reactions B. Type II hypersensitivity reactions C. Type III hypersensitivity reactions D. Type IV hypersensitivity reactions

B. Type II hypersensitivity reactions

76. A soluble antigen and soluble antibody reacting to form an insoluble product describes A. Agglutination reactions B. Heterophile reactions C. Labeled reactions D. Precipitation reactions

D. Precipitation reactions

77. Which of the following is an example of a treponemal antigen test used for the diagnosis of syphilis? A. CRP B. RPR C. VDRL D. FTA-ABS

D. FTA-ABS

78. A serum sample is positive for HBsAg. This result indicates that the person from whom the serum was taken A. Had a hepatitis B infection in the past but overcame the infection B. Has either active or chronic hepatitis B infection C. Was immunized recently against the hepatitis B virus D. Is not infectious for the hepatitis B virus

B. Has either active or chronic hepatitis B infection

79. What is the indicator system used in the complement fixation test? A. Sensitized sheep red blood cells B. Fluorescent-labeled antihuman globulin C. Enzyme-labeled antihuman globulin D. Guinea pig complement

a. Sensitized sheep red blood cells

80. The isotype of an immunoglobulin antibody A. Is defined by the heavy chain B. Is defined as different alleles of the same antibody type (e.g., IgG) C. Is constant for all immunoglobulins of an individual D. Is the variation within the variable region

A. Is defined by the heavy chain

81. A patient report states the presence of serum antibodies to **OspC**. What disease does the patient most likely have? A. Syphilis B. Strep throat C. Lyme disease D. Rubella

C. Lyme disease

82. Patient serum is mixed with a suspension of guinea pig antigen. When the sample is mixed with horse red blood cells, agglutination occurs. This is suggestive of an infection caused by A. Borrelia burgdorferi B. Hepatitis B virus C. Hepatitis C virus D. Epstein-Barr virus

D. Epstein-Barr virus

83. Hashimoto disease is an autoimmune disease primarily involving the A. Kidneys B. Liver C. Lungs D. Thyroid gland

D. Thyroid gland

84. Rheumatic fever sometimes occurs after group A streptococcal infections. In this condition, an autoimmune response attacks the tissue of the heart valves. This phenomenon is an example of A. Epitope spreading B. Molecular mimicry C. Polyclonal B cell activation D. Preferential activation of T helper cells

B. Molecular mimicry

85. "Superantigens" are toxins produced by some strains of Staphylococcus aureus and group A streptococci and cause damage by A. Molecular mimicry B. Polyclonal T-cell activation C. Lysing white blood cells and platelets D. Lysing red blood cells

B. Polyclonal T-cell activation

86. The first serologic marker to appear in patients with acute hepatitis B virus infection is A. Anti-HB B. Anti-HBc C. Anti-HBe D. HBsAg

D. HBsAg

87. A living donor is being sought for a child who requires a kidney transplant. The best odds of finding an MHC-compatible donor occur between the child and A. A sibling (brother or sister) B. An unrelated individual C. The child's father D. The child's mother

A. A sibling (brother or sister)

88. Cells that can act as antigen-presenting cells for exogenous antigens include A. All nucleated cells B. Endothelial cells C. B lymphocytes D. T lymphocytes

C. B lymphocytes

89. In patients with human immunodeficiency virus infection, immune status can be monitored by measuring the ratio of A. CD3+ cells to CD8+ cells B. CD4+ cells to CD8+ cells C. Lymphocytes to monocytes D. T cells to B cells

B. CD4+ cells to CD8+ cells

90. Why does vaccination against hepatitis B virus (HBV) also prevent hepatitis D virus (HDV) infections? A. An immunogen from HBV in the vaccine is also associated with HDV. B. The HBV vaccine induces formation of heterophile antibodies that cross react with HDV. C. The HBV vaccine stimulates liver cells to produce antiviral molecules active against all hepatitis viruses. D. HDV requires the host to be concurrently infected with HBV.

D. HDV requires the host to be concurrently infected with HBV.

91. B lymphocytes and T lymphocytes are derived from A. Hematopoietic stem cells B. Macrophages or monocytes C. Mucosa-associated lymphoid tissue D. The fetal liver

A. Hematopoietic stem cells

92. Contact dermatitis is mediated by A. B lymphocytes B. T lymphocytes C. Macrophages D. Polymorphonuclear cells

B. T lymphocytes

93. In a competitive radioimnumosorbent test (RIST), what does a high signal suggest? A. The patient sample has a low concentration of IgE. B. The patient sample has a low concentration of IgM. C. The patient sample has a high concentration of IgE. D. The patient sample has a high concentration of total antibody.

A. The patient sample has a low concentration of IgE.

94. An antibody titration is depicted in Color Plate 25 *. In this titration, a 0.2 mL aliquot of a patient's serum sample was added to 0.8 mL of saline, and this mixture was placed into tube #1. A 0.5 mL sample was removed from tube #1 and placed into tube #2, containing 0.5 mL of saline. This procedure was repeated through tube #10. The dilutions were assayed for antibody to an infectious agent. How should the antibody titer be reported? A. 256 B. 512 C. 640 D. 1280

C. 640

95. In a chemiluminescent immunologic assay, what is the signal detected? A. Light B. An electric signal C. A purple-colored compound D. A yellow-colored compound

A. Light

96. A 28-year-old female complains to her family physician of abdominal pain, loss of appetite, and low-grade fever. Physical examination reveals abdominal tenderness and a low-grade fever. Her physician orders a hepatitis profile and obtains the results below. Anti-HAV - Nonreactive Anti-HBc-Reactive Anti-HBs-Nonreactive HBsAg- Reactive HBeAg-Reactive Anti-HCV -Nonreactive Which of the following is the most likely conclusion? A. Acute HAV infection B. Acute HBV infection C. Chronic HBV infection D. Immunity to HBV due to past infection

C. Chronic HBV infection

97. An 11-year-old female presents with fever, sore throat, lethargy, and tender cervical lymphadenopathy. Relevant findings include splenomegaly and lymphocytosis, with many large reactive (atypical) lymphocytes. A heterophile antibody test was negative. Further laboratory results were as follows: IgG Titer IgM Titer Cytomegalovirus 20 0 (CMV) Epstein-Barr 0 0 virus (EBV) VGA Mono spot 0 0 What conclusion can be made concerning the diagnosis? A. Acute CMV infection B. Acute EBV infection C. Chronic CMV infection D. Chronic EBV infection

B. Acute EBV infection

98. A male infant had been well until about 5 months of age, at which time he was diagnosed as having otitis media and bronchitis caused by Haemophilus influenzae. Over the next several months he presented with streptococcal pneumonia several times. At 10 months of age a serum protein electrophoresis showed a virtual lack of gamma globulins. Quantitative serum levels were as follows: 75 mg/dL IgG and undetectable levels of IgM, IgA, and IgE. There were a normal number of T cells, and they exhibited normal mitogen stimulation. What disease does this child most likely suffer from? A. Combined immunodeficiency B. DiGeorge syndrome C. latrogenic immunodeficiency D. X-linked agammaglobulinemia

D. X-linked agammaglobulinemia

99. A 25-year-old male presents to his family physician complaining of fatigue, diarrhea, and weight loss of a few months duration. On physical examination the patient is found to have a fever and abdominal discomfort. Laboratory results indicate a white blood cell count of 14.3 X 109/L (reference range 4.8-10.8 X 109/L). Assays for HBSAg and anti-HCV are negative. An ELISA test for antibodies to the human immunodeficiency virus (HIV) performed on the patient's serum is found to be reactive. What step should be taken next? A. Call the physician with the HIV result. B. Repeat the HIV ELISA test on the sample. C. Test the patient's serum for anti-HBs. D. Contact the patient to collect a second sample.

B. Repeat the HIV ELISA test on the sample.

100. A 38-year-old woman visited her physician because of fatigue, fever, and joint pain (proximal interphalangeal, wrist, and knee joints). She also noticed sensitivity to the sun and reported having a rash following recent exposure. The physician noted a rash over her nose and cheeks. Laboratory results included white blood cell count 5.5 X 109/L (reference range 4.8-10.8 X 109/L) and red blood cell count 4.5 X 1012/L (reference range 4.0-5.4 X 1012/L). Urinalysis results were within reference ranges, except for 4+ protein and 1+ RBCs, 0-3 hyaline casts/lpf and 0-1 RBC cast/lpf on microscopic examination. Which of the following tests would be most helpful in diagnosing this patient's condition? A. Anti-nuclear antibody B. a-Fetoprotein C. Anti-streptolysin O D. Hepatitis profile

A. Anti-nuclear antibody