Home Books Review of Medical Microbiology & Immunology: A Guide to Clinical Infectious Diseases, 15e

Part VII: Immunology

Which one of the following is an attribute of the innate, rather than the adaptive (acquired), arm of our host defenses?

(A) Is highly specific in its response to individual bacterial species

(B) Responds to viruses and fungi, but not bacteria

(C) Exhibits memory following exposure to bacteria

(D) Is part of our host defense against bacteria but not against fungi

(E) Is as effective the first time it is exposed to bacteria as it is subsequent times

Regarding haptens, which one of the following is the most accurate?

(A) A hapten is the antigen-binding site of an immunoglobulin.

(B) A hapten cannot induce antibody by itself but can do so when covalently bound to a carrier protein.

(C) A hapten can bind to the antigen receptors of CD4-positive T cells without being processed by antigen-presenting cells.

(D) A hapten is defined by its ability to bind to the smaller of the two polypeptides that comprise the class I MHC proteins.

Certain components of our immune system are characterized by two attributes: being able (1) to respond specifically to microbes and (2) to exhibit memory of having responded to a particular microbe previously. Which one of the following has BOTH specificity and memory?

(A) B cells

(B) Natural killer cells

(C) Dendritic cells

(D) Macrophages

(E) Neutrophils

Your patient says that she must travel on business 3 days from now to a country where hepatitis A is endemic. She just read in the newspaper that there are two types of protection against this disease: one is a vaccine that contains killed hepatitis A virus, and the other is a serum globulin preparation that contains antibodies to the virus. She asks which you would recommend and for what reason?

(A) The vaccine containing killed hepatitis A virus is best because it induces the most antibody.

(B) The vaccine containing killed hepatitis A virus is best because it provides the most long-lived immunity.

(C) The serum globulin preparation containing antibodies against the virus is best because it provides immunity in the shortest time.

(D) The serum globulin preparation containing antibodies against the virus is best because it provides the most long-lived immunity.

Which one of the following is the most accurate statement?

(A) Loss of the epithelial barrier predisposes to fungal infections but not bacterial or viral infections.

(B) The main function of mast cells and eosinophils is to engulf microbes and debris.

(C) Eosinophils and natural killer cells are both innate cells of the myeloid lineage.

(D) Dendritic cells are the primary cell responsible for initiating an adaptive immune response.

Local swelling, redness, warmth, and pain associated with inflammation are primarily due to which one of the following?

(A) Pathogen-associated molecular patterns (PAMPs) recognized by neurons and endothelial cells.

(B) Release of preformed mediators such as leukotrienes and histamine and activated complement.

(C) Cytokines such as tumor necrosis factor-alpha released by T cells.

(D) IgE bound to the surface of eosinophils.

Which one of the following is an accurate statement about antigen-presenting cells (APCs)?

(A) Monocytes can enter inflamed tissue and differentiate into macrophages and dendritic cells.

(B) Dendritic cells turn off CCR7 upon recognition of pathogen-associated molecular patterns.

(C) Macrophages are “professional” APCs that express class II major histocompatibility complex (MHC) but not class I MHC.

(D) Cytosolic antigens are degraded by the proteasome and displayed in complex with class II MHC.

Which one of the following is NOT a primary function of phagocytes?

(A) Engulfing and killing invading microbes

(B) Expression of proinflammatory cytokines and chemokines

(C) Attacking cells with perforins and granzymes

(D) Production of free oxidative radicals

(E) Presentation of antigen peptides in complex with MHC to T cells

Which one of the following describes the immune signals responsible for fever?

(A) Histamine and proteases produced by mast cells

(B) Interleukin-1 (IL-1) and tumor necrosis factor (TNF) produced by macrophages

(C) Type I interferons produced by virus-infected cells

(D) Type II interferon and perforin produced by natural killer (NK) cells

The pathogenesis of chronic granulomatous disease is BEST described as which one of the following?

(A) A defect of chemokine signaling causing impaired granulocyte exit from the bone marrow

(B) A defect complement receptors causing impaired granulocyte activation

(C) A defect in integrin signaling causing impaired granulocyte migration into inflamed tissue

(D) A defect in oxidative burst causing impaired ability of granulocytes to kill microbes

Regarding chemokines, which one of the following is the most accurate?

(A) Chemokines penetrate the membranes of target cells during attack by cytotoxic T cells.

(B) Chemokines bind to the T-cell receptor outside of the antigen-binding site and activate many T cells.

(C) Chemokines attract neutrophils to the site of bacterial infection, thereby playing a role in the inflammatory response.

(D) Chemokines induce gene switching in B cells, which increases the amount of IgE synthesized, thereby predisposing to allergies.

Regarding the genes that encode antibodies, which one of the following is most accurate?

(A) Hypervariable regions are encoded by the genes of both the light and heavy chains.

(B) The genes for the light and heavy chains are linked on the same chromosome adjacent to the human leukocyte antigen (HLA) locus.

(C) During the production of IgG, the light and heavy chains acquire the same antigen binding sites by translocation of the same variable genes.

(D) The gene for the constant region of the gamma heavy chain is first in the sequence of heavy chain genes, and that is why IgG is made in greatest amounts.

Regarding events that occur in the thymus during the maturation of T cells, which one of the following is the most accurate?

(A) T cells bearing antigen receptors that recognize self-antigens are deleted, a process known as “negative selection.”

(B) “Positive selection” ensures that CD4-positive T cells and CD8-positive T cells recognize antigen presented by class I major histocompatibility complex (MHC) proteins and class II MHC proteins, respectively.

(C) T cells bearing antigen receptors that recognize antigen in association with foreign MHC proteins survive, a process known as “positive selection.”

(D) Most mature T cells have both CD4 and CD8 proteins on their surface that ensures their ability to react with antigen presented by either MHC class I or MHC class II proteins.

Which one of the following is a mechanism used by B and T lymphocytes to recognize a diverse range of microbes?

(A) A receptor encoded from birth in the germline

(B) A receptor that recognizes molecular motifs common among many different microbes

(C) A process of clonal selection that eliminates self-reactive cells

(D) A process of DNA recombination that generates clones with unique antigen receptors

(E) A process that shuts off alternate alleles

Which one of the following lists the components of mRNA that might be found in a mature naïve B cell in the secondary lymphoid tissue?

(A) mRNA containing V, D, J, and Cμ segments; mRNA containing V, J, and Cκ segments; and mRNA containing V, J, and Cλ segments

(B) mRNA containing V, D, J, and Cμ segments and mRNA containing V, J, and Cκ segments

(C) mRNA containing V, D, J, and Cγ segments and mRNA containing V, D, J, and Cκ segments.

(D) mRNA containing V, J, and Cγ segments and mRNA containing V, D, J, and Cλ segments

(E) mRNA containing V, D, J, and Cγ segments; mRNA containing V, J, and Cκ segments; and mRNA containing V, J, and Cλ segments

(F) mRNA containing V, J, and Cκ segments and mRNA containing V, J, and Cλ segments.

You are seeing a child with a suspected immunodeficiency, and on testing, you find that he has absent B cells and undetectable antibody levels but slightly elevated numbers of T cells and NK cells. What component of lymphocyte development is most likely defective?

(A) Abnormal assembly of the lambda and kappa light chains

(B) Abnormal function of the recombinase enzymes encoded by recombinase activating genes

(C) Abnormal development of the thymus

(D) Abnormal survival and differentiation of common lymphoid progenitor cells

(E) Abnormal expression of MHC proteins

T-cell–mediated immunity is the main host defense against which one of the following organisms?

(A) Escherichia coli

(B) Mycobacterium leprae

(C) Pseudomonas aeruginosa

(D) Staphylococcus aureus

(E) Streptococcus pneumoniae

You would like to target one of the cells involved in a certain autoimmune disease, described as a CD3-positive CD4-positive cell. Which one of the following is the most accurate about this cell’s function?

(A) Produces IgG

(B) Produces interleukin-2

(C) Kills virus-infected cells

(D) Presents antigen in association with class II major histocompatibility complex (MHC) proteins

(E) Presents antigen in association with class I MHC proteins

Which one of the following sets of cells is primarily responsible for presenting antigen to helper T cells?

(A) B cells and dendritic cells

(B) B cells and cytotoxic T cells

(C) Macrophages and eosinophils

(D) Neutrophils and cytotoxic T cells

(E) Neutrophils and plasma cells

In addition to antigen presentation in association with class I MHC proteins, activation of a CD8-positive T cell requires which one of the following?

(A) High levels of co-stimulation and interleukin-2 produced by CD4-positive T cells

(B) High levels of co-stimulation and gamma interferon produced by macrophages

(C) Presentation of antigen with class II MHC proteins and interleukin-1 produced by macrophages

(D) Presentation of antigen with class II MHC proteins and interleukin-4 produced by CD4-positive T cells

Regarding Th-1, Th-2, and Th-17 cells, which one of the following is the most accurate?

(A) Th-17 cells produce interleukin-17, which stimulates the production of Th-2 cells.

(B) The production of Th-1 cells is enhanced by interleukin-4, whereas the production of Th-2 cells is enhanced by interleukin-2.

(C) Th-2 cells synthesize gamma interferon, which is important in controlling infections caused by Staphylococcus aureus and other pyogenic bacteria.

(D) Th-1 cells control infections caused by Mycobacterium tuberculosis.

Regarding interleukins, which one of the following is the most accurate?

(A) IL-2 is made by B cells and increases class switching from IgM to IgG.

(B) IL-4 is made by cytotoxic T cells and mediates the killing of virus-infected cells.

(C) IL-21 is made by Th-17 cells and enhances the differentiation of cells that defend epithelial barrier surfaces.

(D) IL-12 is made by Tfh cells and increases the generation of cytotoxic T cells.

Your patient is a 20-year-old woman who experienced the sudden onset of fever, vomiting, myalgias, and diarrhea. This was followed by hypotension and a sunburn-like rash over most of her body. You make a presumptive diagnosis of toxic shock syndrome. Which one of the following is the most accurate description of the pathogenesis of this disease?

(A) It is caused by the release of large amounts of histamine from basophils.

(B) It is caused by an insufficient amount of inhibitor of the C1 component of complement.

(C) It is caused by a superantigen that induces an overproduction of cytokines from T cells.

(D) It is caused by a delayed hypersensitivity response to procainamide, which she was taking for her atrial fibrillation.

(E) It is caused by a gene mutation causing excessive signal transduction through the T-cell receptor.

It’s time to play “Who am I?” I am the first class of antibody to appear, so my presence indicates an active infection rather than an infection that occurred in the past. I can fix complement, which is an important defense against many bacterial infections. I am found in plasma as a pentamer.

(A) IgA

(B) IgD

(C) IgE

(D) IgG

(E) IgM

Regarding IgG, which one of the following statements is the most accurate?

(A) Each IgG molecule has one antigen-binding site.

(B) It is the most important antigen receptor on the surface of neutrophils.

(C) During the primary response, it is made in larger amounts than is IgM.

(D) The ability of IgG to fix complement resides on the constant region of the light chain.

(E) It is the only one of the five immunoglobulins that is transferred from mother to fetus in utero.

If a person had a mutation in the gene encoding J (joining) chains, which of the following classes of antibodies could NOT be produced?

(A) IgA and IgM

(B) IgA and IgG

(C) IgG and IgE

(D) IgD and IgE

(E) IgM and IgE

Regarding the function of the different classes of antibodies, which one of the following statements is the most accurate?

(A) IgE blocks the binding of viruses to the gut mucosa.

(B) IgA acts as an antigen receptor on the surface of B cells.

(C) IgD is our most important defense against worm parasites, such as hookworms.

(D) IgG can activate the alternative pathway of complement, resulting in the production of C3a that degrades the bacterial cell wall.

(E) There are receptors for the heavy chain of IgG on the surface of neutrophils that mediate a host defense process called opsonization.

Regarding the genes that encode antibodies, which one of the following statements is most accurate?

(A) Hypervariable regions are encoded by the genes of both the light and heavy chains.

(B) The genes for the light and heavy chains are linked on the same chromosome adjacent to the human leukocyte antigen (HLA) locus.

(C) During the production of IgG, the light and the heavy chains acquire the same antigen-binding sites by translocation of the same variable genes.

(D) The gene for the constant region of the gamma heavy chain is first in the sequence of heavy chain genes, and that is why IgG is made in greatest amounts.

Regarding T-cell–independent activation of B cells, which one of the following statements is true?

(A) “Conjugate” vaccines are most effective in this pathway because the antigen is conjugated to an ingredient that provides a signal 2.

(B) Polysaccharide vaccines make use of adjuvants in part to bypass the requirement for T-cell help in generating antibody.

(C) This pathway is best engaged by short antigens that cross-link relatively few immunoglobulin receptors.

(D) Engagement of the complement system acts to diminish B cell activation.

(E) Antigen presentation by dendritic cells is a key step in this pathway.

Regarding T-cell–dependent activation of B cells, which one of the following statements is true?

(A) B cell competition for T-cell survival factors usually occurs outside of the B-cell follicle.

(B) In this pathway, B cells perform as professional antigen-presenting cells that present antigen to activate naïve T cells.

(C) Chemokines and their receptors are involved in bringing the T cells and dendritic cells together, but they do not have a role in T cell–B cell interactions.

(D) IL-21 is a key cytokine made by T cells that induces B-cell class switching.

(E) The AID enzyme directs V(D)J recombination, somatic hypermutation, and class switching.

A new monoclonal antibody is being tested in a trial for a type of leukemia. The antibody is directed against an antigen found on the leukemia cells. Which one of the following is NOT a possible mechanism of action of this antibody?

(A) The antibody binds to the surface of a target cell, and its Fc region is detected by NK cells, which then kill the target cell.

(B) The antibody binds to the surface of the target cell, and its Fc region recruits complement proteins, which are then activated to kill the cell directly.

(C) The antibody is captured by Fc receptors on the target cell, and binding of antigen to the Fab region recruits phagocytes to kill the target cell.

(D) The antibody binds to the surface of a target cell, and this binding blocks the cell’s ability to receive essential survival signals, causing it to undergo apoptosis.

(E) The antibody binds to the surface of a target cell, and its Fc region recruits complement proteins, which are then detected by phagocytes that engulf and kill the cell.

Regarding solid organ transplantation, which one of the following is the most accurate?

(A) An allograft is a graft that transfers tissue or an organ from one member of a species to a member of another species.

(B) The mother or father of the patient is typically the best donor of a graft because they are two-haplotype matches.

(C) The ABO blood groups of the donor and recipient do not have to be matched because they do not play a role in allograft rejection.

(D) Even when a donor and a recipient are matched at both the class I and class II MHC loci, rejection can occur and the recipient should be given immunosuppressive drugs.

(E) If the same donor is the source of tissue for two grafts to a recipient and the second graft is performed 1 month after the first graft is rejected, then the second graft will not be rejected.

Regarding the MHC proteins and the genes that encode them, which one of the following is the most accurate?

(A) The genes encoding class II MHC proteins are highly polymorphic, whereas the genes encoding class I MHC proteins are not.

(B) The genes encoding class I MHC proteins are located on a different chromosome from the genes encoding class II MHC proteins.

(C) The genes are codominant, and each person expresses class I and class II MHC genes inherited from both mother and father.

(D) Class II MHC proteins are found on the surface of all cells, whereas class I MHC proteins are found only on the surface of phagocytes.

Regarding the graft-versus-host reaction, which one of the following is the most accurate?

(A) It occurs primarily when a kidney is transplanted.

(B) It is caused primarily by mature T cells in the graft.

(C) It occurs primarily when ABO blood groups are matched.

(D) It occurs primarily when the donor is immunocompromised.

(E) It occurs primarily when the haplotypes of the donor and recipient are matched.

Listed below are transplants between individuals with various genotypes and the outcome of these transplants. The genotypes are designated A and B for simplicity. A person who is AA or BB is homozygous, whereas a person who is AB is heterozygous. Regarding outcomes X and Y, which one of the following is the most accurate?

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Genotype of Donor

Genotype of Recipient

Outcome of Transplant

Accepted

Rejected

(A) X is accepted, and Y is accepted.

(B) X is accepted, and Y is rejected.

(C) X is rejected, and Y is accepted.

(D) X is rejected, and Y is rejected.

Regarding the complement pathway, which one of the following is the most accurate?

(A) C3 convertase protects normal cells from lysis by complement.

(B) C3a is a decay-accelerating factor and causes the rapid decay and death of bacteria.

(C) In general, gram-positive bacteria are more likely to be killed by complement than gram-negative bacteria.

(D) The membrane attack complex is formed as a result of activation of the classic pathway but not by activation of the alternative pathway.

(E) The first time a person is exposed to a microorganism, the alternative pathway of complement is more likely to be activated than the classic pathway.

Of the following complement components, which one is the most important opsonin?

(A) C1

(B) C3a

(C) C3b

(D) C5a

(E) C5b

Of the following complement components, which one is the most potent in attracting neutrophils to the site of infection (i.e., acting as a chemokine)?

(A) C1

(B) C2

(C) C3b

(D) C5a

(E) Mannan-binding lectin

Of the following, which one is the most important function of the complex formed by complement components C5b,6,7,8,9?

(A) To enhance antibody production

(B) To inhibit immune complex formation

(C) To opsonize viruses

(D) To perforate bacterial cell membranes

(E) To release histamine from mast cells

A deficiency of which one of the following complement components predisposes to bacteremia caused by members of the genus Neisseria?

(A) C1

(B) C3b

(C) C5a

(D) C5b

(E) C5b,6,7,8,9

Your patient is a 20-year-old woman who complains of swellings on her arms and legs and a feeling of fullness in her throat that makes it difficult to breath. The swellings are not red, hot, or tender. You suspect she may have angioedema caused by a complement abnormality. Of the following, which one is the most likely explanation?

(A) She has too little C1 inhibitor.

(B) She has too little C3b.

(C) She has too little factor B.

(D) She has too much C5a.

(E) She has too much C9.

Which one of the following laboratory tests would be the best to determine the number of CD4-positive cells in the blood of a patient infected with HIV?

(A) Agglutination

(B) Complement fixation

(C) Enzyme-linked immunosorbent assay (ELISA)

(D) Flow cytometry

(E) Immunoelectrophoresis

You have just received a lab report that says your patient is positive for IgM antibody to Borrelia burgdorferi in an enzyme-linked immunosorbent assay (ELISA). This supports your clinical impression that the patient has Lyme disease. Which one of the following best describes how the ELISA was performed? (For brevity, the wash steps have been left out.)

(A) The patient’s serum was reacted with antibody to human mu heavy chain. Then Borrelia antigens labeled with an enzyme were added. Then the enzyme substrate was added, and a color change was observed.

(B) The patient’s serum was reacted with Borrelia antigens. Then antibody to human mu heavy chain labeled with an enzyme was added. Then the enzyme substrate was added, and a color change was observed.

(C) Borrelia antigens were reacted with antibody to human mu heavy chain. Then the patient’s serum labeled with an enzyme was added. Then the enzyme substrate was added, and a color change was observed.

(D) Borrelia antigens were reacted with antibody to human mu heavy chain labeled with an enzyme. Then the patient’s serum was added. Then the enzyme substrate was added, and a color change was observed.

Regarding ABO blood groups, which one of the following is the most accurate?

(A) People who are blood group O have the O antigen on the surface of their red cells.

(B) The A and B blood group antigens are located on the surface of red cells but not on the surface of other cells.

(C) The differences between the A and B blood group antigens are dependent on the presence of different D-amino acids on the cell surface.

(D) People who are blood group O do not have antibodies to A and B blood group antigens and thus can be given both type A and type B blood.

(E) The genes that determine ABO blood groups are codominant, so a person who is blood group AB is expressing both genes that encode the enzymes that synthesize the A and the B blood group antigens.

Regarding hemolytic disease of the newborn (erythroblastosis fetalis), which one of the following is the most accurate?

(A) Maternal red cells are the source of the antigen that induces the antibody.

(B) It typically occurs when the father is Rh-positive and the mother is Rh-negative.

(C) Maternal IgM anti-Rh antibody enters the fetus and causes damage to the fetal red cells.

(D) Symptomatic disease is more likely to occur in the first child than in the subsequent children.

(E) Administration of Rh antigen to the newborn can prevent symptomatic disease if given early enough.

You think your patient has secondary syphilis, and you order a VDRL serologic test. The lab reports that the test is negative. If this is a false-negative result due to the “prozone” phenomenon, which one of the following is the most likely explanation?

(A) The patient’s serum has too much antibody, and the reaction is in the zone of antibody excess.

(B) The patient’s serum has too much antigen, and the reaction is in the zone of antigen-excess phase.

(C) The patient’s serum has too little antibody, and the reaction is in the zone of antibody-deficient phase.

(D) The patient’s serum has too little antigen, and the reaction is in the zone of antigen-deficient phase.

(E) The patient’s serum has an amount of antibody that puts it in the zone of equivalence.

As part of a murder investigation, the blood group of the victim was determined by analyzing the antibodies in her serum. (Unfortunately, the red cells of the victim were lost by the crime squad, so they had to use her serum.) In this test, red cells known to be either O, A, B, or AB were mixed with her serum and agglutination observed. Based on the results in the following table, what is the blood group of the victim?

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Red Blood Cells Used

Agglutination Seen with Victim’s Serum

Yes

(A) Type O

(B) Type A

(C) Type B

(D) Type AB

(E) A laboratory error has occurred, and the test should be repeated

Your patient has episodes of eye tearing, “blood-shot” eyes, and runny nose, which you think may be due to an allergy to some plant pollen. You refer the patient to an allergist, who performs skin tests with various allergens. Within minutes, a wheal-and-flare reaction is seen on the patient’s back at the site where several pollens were injected. What is the most likely sequence of events that produced the wheal-and-flare reaction?

(A) Allergen binds to IgE on the surface of B cells, and IL-4 is released.

(B) Allergen binds to IgE on the surface of mast cells, and histamine is released.

(C) Allergen binds to IgE in the plasma, which activates complement to produce C3b.

(D) Allergen binds to IgE in the plasma, and the allergen-IgE complex binds to the surface of macrophages and IL-1 is released.

One important test to determine whether your patient has been exposed to M. tuberculosis, the organism that causes tuberculosis, is to do a PPD skin test. In this test, PPD extracted from the organism is injected intradermally. Of the following, which one is most likely to occur at the site of a positive PPD?

(A) Cytotoxic T cells kill target cells at the site.

(B) Macrophages and CD4-positive T cells infiltrate the site.

(C) Histamine and leukotrienes are liberated from mast cells at the site.

(D) Immune complexes consisting of PPD and IgG are deposited at the site.

Your patient is a 77-year-old man with enterococcal endocarditis who was treated with penicillin G and gentamicin. Five days later, fever and a diffuse maculopapular rash developed. There is no urticaria, hypotension, or respiratory compromise. Urinalysis revealed proteinuria and granular casts. You suspect he may have serum sickness. Which one of the following immunopathogenic mechanisms is most likely to be the cause?

(A) One of the drugs formed immune complexes with IgG.

(B) One of the drugs activated CD4-positive T cells and macrophages.

(C) One of the drugs activated the alternative pathway of complement.

(D) One of the drugs cross-linked IgE on the mast cells and caused the release of histamine.

Of the following diseases, which one is most likely to be caused by a delayed hypersensitivity reaction?

(A) Autoimmune hemolytic anemia

(B) Contact dermatitis, such as poison oak

(C) Hemolytic disease of the newborn

(D) Poststreptococcal glomerulonephritis

(E) Systemic lupus erythematosus

Atopic individuals (i.e., those with a hereditary predisposition to immediate hypersensitivity reactions) produce an increased amount of IgE. Of the following, which one is the most likely explanation for the increased production of IgE?

(A) Large amounts of IL-1 are produced by dendritic cells.

(B) Large amounts of IL-2 are produced by macrophages.

(C) Large amounts of IL-4 are produced by Th-2 cells.

(D) Large amounts of gamma interferon are produced by Th-1 cells.

(E) Large amounts of C3a are produced by the alternative pathway of complement.

Of the following four types of hypersensitivity reactions, which one causes the hemolysis that occurs in hemolytic disease of the newborn (erythroblastosis fetalis)?

(A) Type I–immediate hypersensitivity

(B) Type II–cytotoxic hypersensitivity

(C) Type III–immune complex hypersensitivity

(D) Type IV–delayed hypersensitivity

Regarding immunologic tolerance, which one of the following is the most accurate?

(A) Clonal deletion occurs with T cells but not with B cells.

(B) Tolerance to certain self-antigens occurs by negative selection of immature T cells in the thymus.

(C) The presence of B7 on the surface of the antigen-presenting cell is one of the essential steps required to establish tolerance.

(D) Tolerance is easier to establish in adults than in newborns because more self-reactive T cells have undergone apoptosis in adults than in newborns.

(E) Once tolerance is established to an antigen, it is permanent (i.e., that individual cannot react against that antigen even though the antigen is no longer present).

Antibodies against normal components of the body typically occur in autoimmune diseases. In which one of the following sets of two diseases do antibodies against DNA occur in one disease and antibodies against IgG occur in the other disease?

(A) Myasthenia gravis and systemic lupus erythematosus

(B) Pernicious anemia and rheumatic fever

(C) Rheumatic fever and myasthenia gravis

(D) Rheumatoid arthritis and pernicious anemia

(E) Systemic lupus erythematosus and rheumatoid arthritis

Regarding the pathogenesis of autoimmune diseases, which one of the following is the most accurate?

(A) In reactive arthritis, neuropathy occurs following viral respiratory tract infections.

(B) In myasthenia gravis, antibodies are formed against acetylcholine at the neuromuscular junction.

(C) In Goodpasture’s syndrome, antibodies are formed against the synovial membrane in the large weight-bearing joints.

(D) In autoimmune hemolytic anemia, the red cells are destroyed by tumor necrosis factor produced by activated macrophages.

(E) In Graves’ disease, antibodies bind to the receptor for thyroid-stimulating hormone, which stimulates the thyroid to produce excess thyroxine.

Your patient is a 25-year-old woman with a fever, a malar facial rash, alopecia, and ulcerations on two fingertips. Urinalysis shows proteinuria. You suspect she has systemic lupus erythematosus. Which one of the following is the most likely explanation for her proteinuria?

(A) Cytotoxic T cells attack the glomerular basement membrane.

(B) An IgE-mediated response releases histamine and leukotrienes that damage the tubules.

(C) A delayed hypersensitivity response consisting of macrophages and CD4-positive T cells damages the glomeruli.

(D) Immune complexes are trapped by glomeruli and activate complement, then C5a attracts neutrophils that damage the glomeruli.

Regarding tumor immunity, which one of the following is the most accurate?

(A) Both cytotoxic T cells and cytotoxic antibodies attack human cancer cells.

(B) An elevated level of alpha-fetoprotein is a marker for carcinoma of the lung.

(C) A declining level of carcinoembryonic antigen (CEA) is an indication that the patient’s colon cancer has recurred.

(D) Cancer cells induced by chemicals have new antigens on the surface, but cancer cells induced by viruses do not.

(E) Natural killer (NK) cells do not participate in the cell-mediated response to cancer cells because they do not have an antigen-specific receptor on their surface.

Your patient is a 2-year-old boy who has had several episodes of pustules and lymphadenitis caused by Staphylococcus aureus. His immunoglobulin and complement levels are normal. A nitro blue tetrazolium test reveals defective cells. Which one of the following cells is the most likely to be defective?

(A) CD4-positive T lymphocytes

(B) CD8-positive T lymphocytes

(C) Eosinophils

(D) Natural killer cells

(E) Neutrophils

Your patient is a 25-year-old woman who has had several serious episodes of bacterial pneumonia in the past 5 months. She has not had frequent or unusual infections prior to the onset of these pneumonias. Which one of the following is the most likely immunodeficiency that predisposes her to these infections?

(A) She is likely to have a defect in her cytotoxic T cells.

(B) She is likely to have a reduced level of immunoglobulins.

(C) She is likely to have a mutation in the gene that encodes the C3a portion of complement.

(D) She is likely to have a mutation in one of the genes that encode the class I MHC proteins.

Regarding Bruton’s agammaglobulinemia, which one of the following is most accurate?

(A) There is very little IgG produced, but IgM and IgA levels are normal.

(B) Viral infections are more common than pyogenic bacterial infections.

(C) The number of B cells is normal, but they cannot differentiate into plasma cells.

(D) There is a mutation in the gene for tyrosine kinase, an important enzyme in the signal transduction pathway in B cells.

Which one of the following is the most accurate description of the defect in chronic granulomatous disease?

(A) There is an inability to produce an oxidative burst.

(B) There is a failure to produce sufficient interleukin-2.

(C) There is a deficiency of a late-acting complement component.

(D) There is a mutant protein kinase in a signal transduction pathway.

(E) There is a mutation in the gene that encodes a class II MHC protein.

Which one of the following immunodeficiencies is most likely to predispose to both pyogenic bacterial infections and viral infections in a young child?

(A) Bruton’s agammaglobulinemia

(B) Chronic granulomatous disease

(C) DiGeorge’s syndrome

(D) Job’s syndrome

(E) Severe combined immunodeficiency disease

Regarding immunodeficiency diseases, which one of the following is most accurate?

(A) Patients who have a deficiency of IgA have a high incidence of pyogenic infections of the sinuses and lungs.

(B) Common variable hypogammaglobulinemia typically occurs in boys under the age of 6 months and results from a virtual absence of B cells.

(C) In Wiskott-Aldrich syndrome, the combination of antibody deficiency and complement deficiency leads to disseminated viral and fungal infections.

(D) Patients with DiGeorge’s syndrome (congenital thymic aplasia) have a reduced number of both T cells and B cells and have severe infections caused by pyogenic bacteria.

(E) Patients who cannot produce one or more of the late-acting complement components, such as C6, C7, C8, or C9, have episodes of angioedema, including laryngeal edema that can be fatal.

Which category of hypersensitivity BEST describes hemolytic disease of the newborn caused by Rh incompatibility?

(A) Atopic or anaphylactic

(B) Cytotoxic

(C) Immune complex

(D) Delayed

The principal difference between cytotoxic (type II) and immune complex (type III) hypersensitivity is:

(A) The class (isotype) of antibody

(B) Whether the antibody reacts with the antigen on the cell or reacts with antigen before it interacts with the cell

(C) The participation of complement

(D) The participation of T cells

A child stung by a bee experiences respiratory distress within minutes and lapses into unconsciousness. This reaction is probably mediated by:

(A) IgE antibody

(B) IgG antibody

(C) Sensitized T cells

(D) Complement

(E) IgM antibody

A patient with rheumatic fever develops a sore throat from which β-hemolytic streptococci are cultured. The patient is started on treatment with penicillin, and the sore throat resolves within several days. However, 7 days after initiation of penicillin therapy, the patient develops a fever of 103°F, a generalized rash, and proteinuria. This MOST probably resulted from:

(A) Recurrence of the rheumatic fever

(B) A different infectious disease

(C) An IgE response to penicillin

(D) An IgG-IgM response to penicillin

(E) A delayed hypersensitivity reaction to penicillin

A kidney biopsy specimen taken from a patient with acute glomerulonephritis and stained with fluorescein-conjugated anti-human IgG antibody would probably show:

(A) No fluorescence

(B) Uniform fluorescence of the glomerular basement membrane

(C) Patchy, irregular fluorescence of the glomerular basement membrane

(D) Fluorescent B cells

(E) Fluorescent macrophages

A patient with severe asthma gets no relief from antihistamines. The symptoms are MOST likely to be caused by:

(A) Interleukin-2

(B) Slow-reacting substance A (leukotrienes)

(C) Serotonin

(D) Bradykinin

Hypersensitivity to penicillin and hypersensitivity to poison oak are both:

(A) Mediated by IgE antibody

(B) Mediated by IgG and IgM antibody

(C) Initiated by haptens

(D) Initiated by Th-2 cells

A recipient of a 10/10 HLA-matched kidney from a relative still needs immunosuppression to prevent graft rejection because:

(A) Graft-versus-host disease is a problem

(B) Class II MHC antigens will not be matched

(C) Minor histocompatibility antigens will not be matched

(D) Complement components will not be matched

Bone marrow transplantation in immunocompromised patients presents which major problem?

(A) Potentially lethal graft-versus-host disease

(B) High risk of T-cell leukemia

(C) Inability to use a live donor

(D) Delayed hypersensitivity

What is the role of class II MHC proteins on donor cells in graft rejection?

(A) They are the receptors for interleukin-2, which is produced by macrophages when they attack the donor cells.

(B) They are recognized by helper T cells, which then activate cytotoxic T cells to kill the donor cells.

(C) They induce the production of blocking antibodies that protect the graft.

(D) They induce IgE, which mediates graft rejection.

Grafts between genetically identical individuals (i.e., identical twins):

(A) Are rejected slowly as a result of minor histocompatibility antigens

(B) Are subject to hyperacute rejection

(C) Are not rejected, even without immunosuppression

(D) Are not rejected if a kidney is grafted, but skin grafts are rejected

Penicillin is a hapten in both humans and mice. To explore the hapten–carrier relationship, a mouse was injected with penicillin covalently bound to bovine serum albumin and, at the same time, with egg albumin to which no penicillin was bound. Of the following, which one will induce a secondary response to penicillin when injected into the mouse 1 month later?

(A) Penicillin

(B) Penicillin bound to egg albumin

(C) Egg albumin

(D) Bovine serum albumin

Bovine serum albumin is the correct answer because it activates helper T cells that are required to provide the interleukins needed for a secondary response. Penicillin alone is incorrect because it is a hapten and cannot activate helper T cells. Choices B and C refer to egg albumin, which can activate helper T cells but not the ones that were activated by the initial stimulus that contained penicillin bound to bovine serum albumin.

AIDS is caused by a human retrovirus that kills:

(A) B lymphocytes

(B) Lymphocyte stem cells

(C) CD4-positive T lymphocytes

(D) CD8-positive T lymphocytes

Which one of the following mechanisms is a feature of tumor cells that successfully avoid killing by the adaptive immune system?

(A) Increased expression of class I MHC proteins

(B) Increased expression of programmed cell death ligand-1 (PD-L1)

(C) Increased expression of gamma interferon

(D) Increased expression of neoantigens

Polyomavirus (a DNA virus) causes tumors in mice lacking a thymus, but not in normal mice. The BEST interpretation is that:

(A) Macrophages are required to reject polyomavirus-induced tumors.

(B) Natural killer cells can reject polyomavirus-induced tumors without help from T lymphocytes.

(C) T lymphocytes play an important role in the rejection of polyomavirus-induced tumors.

(D) B lymphocytes play no role in rejection of polyomavirus-induced tumors.

C3 is cleaved to form C3a and C3b by C3 convertase. C3b is involved in all of the following EXCEPT:

(A) Increasing vascular permeability

(B) Promoting phagocytosis

(C) Forming alternative-pathway C3 convertase

(D) Forming C5 convertase

After binding to its specific antigen, a B lymphocyte may switch its:

(A) Immunoglobulin light chain isotype

(B) Immunoglobulin heavy chain class

(C) Variable region of the immunoglobulin heavy chain

(D) Constant region of the immunoglobulin light chain

Diversity is an important feature of the immune system. Which one of the following statements about it is INCORRECT?

(A) Humans can make antibodies with about 10¹¹ different V_H × V_L combinations.

(B) A single cell can synthesize IgM antibody and then switch to IgA antibody.

(C) The hematopoietic stem cell carries the genetic potential to create all possible immunoglobulin proteins.

(D) A single B lymphocyte can produce antibodies of many different specificities, but a plasma cell is monospecific.

C3a and C5a can cause:

(A) Bacterial lysis

(B) Increased vascular permeability

(C) Phagocytosis of IgE-coated bacteria

(D) Aggregation of C4 and C2

Neutrophils are attracted to an infected area by:

(A) IgM

(B) C1

(C) C5a

(D) C8

Complement fixation refers to:

(A) The ingestion of C3b-coated bacteria by macrophages

(B) The destruction of complement in serum by heating at 56°C for 30 minutes

(C) The binding of complement components by antigen–antibody complexes

(D) The interaction of C3b with mast cells

The classic complement pathway is initiated by interaction of C1 with:

(A) Antigen

(B) Factor B

(C) Antigen–IgG complexes

(D) Bacterial lipopolysaccharides

Patients with severely reduced C3 levels tend to have:

(A) Increased numbers of severe viral infections

(B) Increased numbers of severe bacterial infections

(C) Low gamma globulin levels

(D) Frequent episodes of hemolytic anemia

Individuals with a genetic deficiency of C6 have:

(A) Decreased resistance to viral infections

(B) Increased hypersensitivity reactions

(C) Increased frequency of cancer

(D) Increased frequency of Neisseria bacteremia

Natural killer cells are:

(A) B cells that can kill without complement

(B) Cytotoxic T cells

(C) Increased by immunization

(D) Able to kill virus-infected cells without prior sensitization

A positive tuberculin skin test (a delayed hypersensitivity reaction) indicates that:

(A) A humoral immune response has occurred

(B) A cell-mediated immune response has occurred

(C) Both the T- and B-cell systems are functional

(D) Only the B-cell system is functional

Reaction to poison ivy or poison oak is:

(A) An IgG-mediated response

(B) An IgE-mediated response

(C) A T-cell–mediated response

(D) An Arthus reaction

A child disturbs a wasp nest, is stung repeatedly, and goes into shock within minutes, manifesting respiratory failure and vascular collapse. This is MOST likely to be due to:

(A) Systemic anaphylaxis

(B) Serum sickness

(C) An Arthus reaction

(D) Cytotoxic hypersensitivity

“Isotype switching” of immunoglobulin classes by B cells involves:

(A) Simultaneous insertion of V_H genes adjacent to each C_H gene

(B) Successive insertion of a V_H gene adjacent to different C_H genes

(C) Activation of homologous genes on chromosome 6

(D) Switching of light chain types (kappa and lambda)

Which one of the following pairs of genes is linked on a single chromosome?

(A) V gene for lambda chain and C gene for kappa chain

(B) C gene for gamma chain and C gene for kappa chain

(C) V gene for lambda chain and V gene for heavy chain

(D) C gene for gamma chain and C gene for alpha chain

Antigen-binding determinants are located within:

(A) Hypervariable regions of heavy and light chains

(B) Constant regions of light chains

(C) Constant regions of heavy chains

(D) The hinge region

A primary immune response in an adult human requires approximately how much time to produce detectable antibody levels in the blood?

(A) 12 hours

(B) 3 days

(C) 1 week

(D) 3 weeks

The membrane IgM and IgD on the surface of an individual B cell:

(A) Have identical heavy chains but different light chains

(B) Are identical except for their C_H regions

(C) Are identical except for their V_H regions

(D) Have different V_H and V_L regions

During the maturation of a B lymphocyte, the first immunoglobulin heavy chain synthesized is the:

(A) Mu chain

(B) Gamma chain

(C) Epsilon chain

(D) Alpha chain

In the immune response to a hapten–protein conjugate, in order to get anti-hapten antibodies, it is essential that:

(A) The hapten be recognized by helper T cells

(B) The protein be recognized by helper T cells

(C) The protein be recognized by B cells

(D) The hapten be recognized by suppressor T cells

Which one of the following is NOT an example of a “second signal” that leads to proliferation and activation of B cells?

(A) CD40 ligand (CD40L) that binds B-cell CD40

(B) Degradation components of C3 that bind B-cell complement receptor 2

(C) Pathogen-associated molecular patterns (PAMPS) that bind B-cell TLRs

(D) Antigen binding to the B-cell surface immunoglobulin

Which one of the following sequences is appropriate for testing a patient for antibody against the AIDS virus with the ELISA procedure? (The assay is carried out in a plastic plate with an incubation and a wash step after each addition except the final one.)

(A) Patient’s serum/enzyme substrate/HIV antigen/enzyme-labeled antibody against HIV

(B) HIV antigen/patient’s serum/enzyme-labeled antibody against human gamma globulin/enzyme substrate

(C) Enzyme-labeled antibody against human gamma globulin/patient’s serum/HIV antigen/enzyme substrate

(D) Enzyme-labeled antibody against HIV/HIV antigen/patient’s serum/enzyme substrate

The BEST method to demonstrate IgG on the glomerular basement membrane in a kidney tissue section is the:

(A) Precipitin test

(B) Complement fixation test

(C) Agglutination test

(D) Indirect fluorescent-antibody test

A woman had a high fever, hypotension, and a diffuse macular rash. When all cultures showed no bacterial growth, a diagnosis of toxic shock syndrome was made. Regarding the mechanism by which the toxin causes this disease, which one of the following is LEAST accurate?

(A) The toxin is not processed within the macrophage.

(B) The toxin binds to both the class II MHC protein and the T-cell receptor.

(C) The toxin activates many CD4-positive T cells, and large amounts of interleukins are released.

(D) The toxin has an A-B subunit structure—the B subunit binds to a receptor, and the A subunit enters the cells and activates them.

A patient with a central nervous system disorder is maintained on the drug methyldopa. Hemolytic anemia develops, which resolves shortly after the drug is withdrawn. This is MOST probably an example of:

(A) Atopic hypersensitivity

(B) Cytotoxic hypersensitivity

(C) Immune-complex hypersensitivity

(D) Cell-mediated hypersensitivity

Which one of the following substances is NOT a major cytokine released by activated helper T cells?

(A) Alpha interferon

(B) Gamma interferon

(C) Interleukin-2

(D) Interleukin-4

A delayed hypersensitivity reaction is characterized by:

(A) Edema without a cellular infiltrate

(B) An infiltrate composed of neutrophils

(C) An infiltrate composed of helper T cells and macrophages

(D) An infiltrate composed of eosinophils

Two dissimilar inbred strains of mice, A and B, are crossed to yield an F₁ hybrid strain, AB. If a large dose of spleen cells from an adult A mouse is injected into an adult AB mouse, which one of the following is MOST likely to occur?

(A) The spleen cells will be destroyed.

(B) The spleen cells will survive and will have no effect in the recipient.

(C) The spleen cells will induce a graft-versus-host reaction in the recipient.

(D) The spleen cells will survive and induce tolerance of strain A grafts in the recipient.

Spleen cells from the adult donor A will recognize the B antigen on the recipient's cells as foreign. Spleen cells from the adult donor will contain mature CD4 and CD8 cells that will attack the recipient cells, causing a graft-versus-host reaction; therefore, answer C is correct. Because the recipient is tolerant to antigen A, the donor A spleen cells will not be destroyed; therefore, answer A is incorrect. Answer B is incorrect because although the donor cells will survive, they will have an effect on the recipient. Answer D is incorrect because the recipient is already tolerant to antigen A.

Two dissimilar inbred strains of mice, A and B, are crossed to yield an F₁ hybrid strain, AB. If a large dose of spleen cells from an adult A mouse is injected into an adult AB mouse. If adult AB spleen cells are injected into a newborn B mouse, which one of the following is MOST likely to occur?

(A) The spleen cells will be destroyed.

(B) The spleen cells will survive without any effect on the recipient.

(C) The spleen cells will induce a graft-versus-host reaction in the recipient.

(D) The spleen cells will survive and induce tolerance of strain A grafts in the recipient.

Because the donor AB spleen cells will not see any foreign antigen in the recipient, no graft-versus-host reaction will occur; therefore, answer C is incorrect. The immune cells of the newborn mouse do not have the capability to kill the donor cells; therefore, answer A is incorrect. Answer D is more correct than answer B because the donor cells will survive and induce tolerance to antigen A in the newborn recipient.

The minor histocompatibility antigens on cells:

(A) Are detected by reaction with antibodies and complement

(B) Are controlled by several genes in the major histocompatibility complex

(C) Are unimportant in human transplantation

(D) Induce reactions that can cumulatively lead to a strong rejection response

Which one of the following is NOT true of class I MHC antigens?

(A) They can be assayed by a cytotoxic test that uses antibody and complement.

(B) One of their two polypeptide chains is a beta-2 microglobulin.

(C) They are encoded by at least three gene loci in the major histocompatibility complex.

(D) They are found mainly on B cells, macrophages, and activated T cells.

An antigen found in relatively high concentration in the plasma of normal fetuses and a high proportion of patients with progressive carcinoma of the colon is:

(A) Viral antigen

(B) Carcinoembryonic antigen

(C) α-Fetoprotein

(D) Heterophil antigen

An antibody directed against the hypervariable regions of a human IgG antibody would react with:

(A) The Fc part of the IgG

(B) An IgM antibody produced by the same plasma cell that produced the IgG

(C) All human kappa chains

(D) All human gamma chains

Which one of the following is NOT true of the gene segments that combine to make up a heavy chain gene?

(A) Many V region segments are available.

(B) Several J segments and several D segments are available.

(C) V, D, and J segments combine to encode the antigen-binding site.

(D) A V segment and a J segment are preselected by an antigen to make up the variable-region portion of the gene.

When immune complexes from the serum are deposited on glomerular basement membrane, damage to the membrane is caused mainly by:

(A) Gamma interferon

(B) Phagocytosis

(C) Cytotoxic T cells

(D) Enzymes released by polymorphonuclear cells

If an individual was genetically unable to make J chains, which immunoglobulin(s) would be affected?

(A) IgG

(B) IgM

(C) IgA

(D) IgG and IgM

(E) IgM and IgA

The antigen-binding site on antibodies is formed primarily by:

(A) The constant regions of H and L chains

(B) The hypervariable regions of H and L chains

(C) The hypervariable regions of H chains

(D) The variable regions of H chains

(E) The variable regions of L chains

The class of immunoglobulin present in highest concentration in the blood of a human newborn is

(A) IgG

(B) IgM

(C) IgA

(D) IgD

(E) IgE

Individuals of blood group type AB:

(A) Are Rh(D)-negative

(B) Are “universal recipients” of transfusions

(C) Have circulating anti-A and anti-B antibodies

(D) Have the same haplotype

Cytotoxic T cells induced by infection with virus A will kill target cells:

(A) From the same host infected with any virus

(B) Infected by virus A and identical at class I MHC loci of the cytotoxic T cells

(C) Infected by virus A and identical at class II MHC loci of the cytotoxic T cells

(D) Infected with a different virus and identical at class I MHC loci of the cytotoxic cells

(E) Infected with a different virus and identical at class II MHC loci of the cytotoxic cells

Antigen-presenting cells that activate helper T cells must express which one of the following on their surfaces?

(A) IgE

(B) Gamma interferon

(C) Class I MHC antigens

(D) Class II MHC antigens

Which one of the following does NOT contain C3b?

(A) Classic-pathway C5 convertase

(B) Alternative-pathway C5 convertase

(C) Classic-pathway C3 convertase

(D) Alternative-pathway C3 convertase

Which one of the following is NOT true regarding the alternative complement pathway?

(A) It can be triggered by infectious agents in absence of antibody.

(B) It does not require C1, C2, or C4.

(C) It cannot be initiated unless C3b fragments are already present.

(D) It has the same terminal sequence of events as the classic pathway.

In setting up a complement fixation test to detect antibody in the patient’s serum, the reactants should be added in what sequence? (Ag = antigen; C = complement; EA = antibody-coated indicator erythrocytes.)

(A) Ag + EA + C/wait/ + patient’s serum

(B) C + patient’s serum + EA/wait/ + Ag

(C) Ag + patient’s serum + EA/wait/ + C

(D) Ag + patient’s serum + C/wait/ + EA

An effective new therapy is approved for autoimmune diseases in which Th-17 cells are overactivated. Which one of the following interleukins (ILs) is most likely to be inhibited by this new therapy?

(A) IL-10

(B) IL-12

(C) IL-13

(D) IL-23

Complement lyses cells by:

(A) Enzymatic digestion of the cell membrane

(B) Activation of adenylate cyclase

(C) Insertion of complement proteins into the cell membrane

(D) Inhibition of elongation factor-2

Graft and tumor rejection are mediated primarily by:

(A) Non–complement-fixing antibodies

(B) Phagocytic cells

(C) Mast cells

(D) Cytotoxic T cells

Which one of the following properties of antibodies is NOT dependent on the structure of the heavy chain constant region?

(A) Ability to cross the placenta

(B) Isotype (class)

(C) Ability to fix complement

(D) Affinity for antigen

In which one of the following situations would a graft-versus-host reaction be MOST likely to occur? (Mouse strains A and B are highly inbred; AB is an F₁ hybrid between strain A and strain B.)

(A) Newborn strain A spleen cells injected into a strain B adult

(B) X-irradiated adult strain A spleen cells injected into a strain B adult

(C) Adult strain A spleen cells injected into an x-irradiated strain AB adult

(D) Adult strain AB spleen cells injected into a strain A newborn

Graft versus host (GVH) reaction is most likely to occur when the recipient is immunocompromised and functioning donor T cells recognize a foreign antigen in the recipient. Answer C is correct because the recipient is x-irradiated (immunocompromised) and the donor A T cells recognize the B antigen in the recipient as foreign. In answers A and B, the recipient is not immunocompromised and in answer D, the newborn recipient is relatively immunocompromised but the donor T cells are tolerant to the A antigen in the recipient so no GVH reaction occurs.

A researcher takes cells from patient A, cultures them in a lab, and infects them with a virus. CD8-positive T cells from patient B are then added to the virus-infected cell culture. After several days of culture, no cytokine production or cytotoxicity is seen. Of the following, which one is the BEST explanation?

(A) Patient B was previously exposed to this virus.

(B) Patient A and patient B do not share HLA alleles.

(C) The virus caused an increase in expression of B7 proteins on patient A’s cells.

(D) The cultured, virus-infected cells from patient A were not dendritic cells or B cells.

A patient skin-tested with purified protein derivative (PPD) to determine previous exposure to Mycobacterium tuberculosis develops induration at the skin test site 48 hours later. Histologically, the reaction site would MOST probably show:

(A) Eosinophils

(B) Neutrophils

(C) Helper T cells and macrophages

(D) B cells

Hemolytic disease of the newborn caused by Rh blood group incompatibility requires maternal antibody to enter the fetal bloodstream. Therefore, the mediator of this disease is:

(A) IgE antibody

(B) IgG antibody

(C) IgM antibody

(D) IgA antibody

An Rh-negative woman married to a heterozygous Rh-positive man has three children. The probability that all three of their children are Rh-positive is:

(A) 1:2

(B) 1:4

(C) 1:8

(D) Zero

Which one of the following statements BEST explains the relationship between inflammation of the heart (carditis) and infection with group A β-hemolytic streptococci?

(A) Streptococcal antigens induce antibodies cross-reactive with heart tissue.

(B) Streptococci are polyclonal activators of B cells.

(C) Streptococcal antigens bind to IgE on the surface of heart tissue, and histamine is released.

(D) Streptococci are ingested by neutrophils that release proteases that damage heart tissue.

Your patient became ill 10 days ago with a viral disease. Laboratory examination reveals that the patient’s antibodies against this virus have a high ratio of IgM to IgG. What is your conclusion?

(A) It is unlikely that the patient has encountered this organism previously.

(B) The patient is predisposed to IgE-mediated hypersensitivity reactions.

(C) The information given is irrelevant to previous antigen exposure.

(D) It is likely that the patient has an autoimmune disease.

If you measure the ability of cytotoxic T cells from an HLA-B27 person to kill virus X–infected target cells, which one of the following statements is CORRECT?

(A) Any virus X–infected target cell will be killed.

(B) Only virus X–infected cells of HLA-B27 type will be killed.

(C) Any HLA-B27 cell will be killed.

(D) No HLA-B27 cell will be killed.

You have a patient who makes autoantibodies against his own red blood cells, leading to hemolysis. Which one of the following mechanisms is MOST likely to explain the hemolysis?

(A) Perforins from cytotoxic T cells lyse the red cells.

(B) Neutrophils release proteases that lyse the red cells.

(C) Interleukin-2 binds to its receptor on the red cells, which results in lysis of the red cells.

(D) Complement is activated, and membrane attack complexes lyse the red cells.

Your patient is a child who has no detectable T or B cells. This immunodeficiency is most probably the result of a defect in:

(A) The thymus

(B) The membrane attack complex of complement

(C) T cell–B cell interaction

(D) Stem cells originating in the bone marrow

The role of dendritic cells during an antibody response is to:

(A) Make antibody

(B) Lyse virus-infected target cells

(C) Activate cytotoxic T cells

(D) Process antigen and present it

The structural basis of blood group A and B antigen specificity is:

(A) A single terminal sugar residue

(B) A single terminal amino acid

(C) Multiple differences in the carbohydrate portion

(D) Multiple differences in the protein portion

Complement can enhance phagocytosis because of the presence on macrophages and neutrophils of receptors for:

(A) Factor D

(B) C3b

(C) C6

(D) C9

The main advantage of passive immunization over active immunization is that:

(A) It can be administered orally.

(B) It provides antibody more rapidly.

(C) Antibody persists for a longer period.

(D) It contains primarily IgM.

On January 15, a patient developed an illness suggestive of influenza, which lasted 1 week. On February 20, she had a similar illness. She had no influenza immunization during this period. Her hemagglutination inhibition titer to influenza A virus was 10 on January 18, 40 on January 30, and 320 on February 20. Which one of the following is the MOST appropriate interpretation?

(A) The patient was ill with influenza A on January 15.

(B) The patient was ill with influenza A on February 20.

(C) The patient was not infected with influenza virus.

(D) The patient has an autoimmune disease.

An individual who is heterozygous for Gm allotypes contains two allelic forms of IgG in serum, but individual lymphocytes produce only one of the two forms. This phenomenon, known as “allelic exclusion,” is consistent with:

(A) A rearrangement of a heavy chain gene on only one chromosome in a lymphocyte

(B) Rearrangements of heavy chain genes on both chromosomes in a lymphocyte

(C) A rearrangement of a light chain gene on only one chromosome in a lymphocyte

(D) Rearrangements of light chain genes on both chromosomes in a lymphocyte

Each of the following statements concerning class I MHC proteins is correct EXCEPT:

(A) They are cell surface proteins on virtually all cells.

(B) They are recognition elements for cytotoxic T cells.

(C) They are codominantly expressed.

(D) They are important in the skin test response to Mycobacterium tuberculosis.

Which one of the following is the BEST method of reducing the effect of graft-versus-host disease in a bone marrow recipient?

(A) Matching the complement components of donor and recipient

(B) Administering alpha interferon

(C) Removing mature T cells from the graft

(D) Removing pre-B cells from the graft

Regarding Th-1 and Th-2 cells, which one of the following is LEAST accurate?

(A) Th-1 cells produce gamma interferon and promote cell-mediated immunity.

(B) Th-2 cells produce interleukin-4 and interleukin-5 and promote allergy.

(C) Both Th-1 and Th-2 cells have both CD3 and CD4 proteins on their outer cell membrane.

(D) Before naive Th cells differentiate into Th-1 or Th-2 cells, they are double-positives (i.e., they produce both gamma interferon and interleukin-4).

Each of the following statements concerning the variable regions of heavy chains and the variable regions of light chains in a given antibody molecule is correct EXCEPT:

(A) They have the same amino acid sequence.

(B) They define the specificity for antigen.

(C) They are encoded on different chromosomes.

(D) They contain the hypervariable regions.

Each of the following statements concerning class II MHC proteins is correct EXCEPT:

(A) They are found on the surface of both B and T cells.

(B) They have a high degree of polymorphism.

(C) They are involved in the presentation of antigen by macrophages.

(D) They have a binding site for CD4 proteins.

Which one of the following statements concerning immunoglobulin allotypes is CORRECT?

(A) Allotypes are found only on heavy chains.

(B) Allotypes are determined by class I MHC genes.

(C) Allotypes are confined to the variable regions.

(D) Allotypes are due to genetic polymorphism within a species.

Each of the following statements concerning immunologic tolerance is correct EXCEPT:

(A) Tolerance is not antigen-specific (i.e., paralysis of the immune cells results in a failure to produce a response against many antigens).

(B) Tolerance is more easily induced in T cells than in B cells.

(C) Tolerance is more easily induced in neonates than in adults.

(D) Tolerance is more easily induced by simple molecules than by complex ones.

Each of the following statements concerning a hybridoma cell is correct EXCEPT:

(A) The spleen cell component provides the ability to form antibody.

(B) The myeloma cell component provides the ability to grow indefinitely.

(C) The antibody produced by a hybridoma cell is IgM, because heavy chain switching does not occur.

(D) The antibody produced by a hybridoma cell is homogeneous (i.e., it is directed against a single epitope).

Each of the following statements concerning haptens is correct EXCEPT:

(A) A hapten can combine with (bind to) an antibody.

(B) A hapten cannot induce an antibody by itself; rather, it must be bound to a carrier protein to be able to induce antibody.

(C) In both penicillin-induced anaphylaxis and poison ivy, the allergens are haptens.

(D) Haptens must be processed by CD8⁺ cells to become immunogenic.

Major source of interleukin-1

(A) T cells

(B) B cells

(C) Macrophages

(D) B cells and macrophages