Final Flashcards
1
Q
- Which of the following statements about cell-mediated immunity (CMI) is NOT true?
A. Deficiencies in CMI result in susceptibility to infections by viruses and intracellular bacteria.
B. CMI can be adoptively transferred by injecting serum from one individual to another.
C. Delayed-type hypersensitivity (DTH) is not a protective response against intracellular bacteria such as Mycobacterium tuberculosis.
D. The principal form of CMI that protects against viral infections is mediated by CD8+ cytolytic T lymphocytes.
E. Phagocytes are essential in the effector phase of CMI responses to bacteria such as Listeria monocytogenes.
A
B. CMI can be adoptively transferred by injecting serum from one individual to another.
2
Q
- The induction phase of a cell-mediated immune response includes which of the following events?
A. CD4+ T cell secretion of interferon- leading to macrophage activation
B. CD8+ T cell lysis of a virally infected cell
C. Clonal expansion of CD8+ T cells within a lymph node
D. Migration of CD4+ effector T cells from blood vessels into a tissue site of infection
E. Migration of a naive CD4+ T cell from the thymic medulla into the circulation
A
C. Clonal expansion of CD8+ T cells within a lymph node
3
Q
3. Which of the following comparisons between TH1 and TH2 cells is true? A. TH1 cells produce interleukin (IL)-1 but not IL-2, and TH2 cells produce IL-2 but not IL-1. B. TH1 cells are class I major histocompatibility complex (MHC) restricted, and TH2 cells are class II MHC restricted. C. The chemokine receptors CXCR3 and CCR5 are more highly expressed on TH2 cells than on TH1 cells. D. TH2 cells are more likely to bind to E-selectin and P-selectin on endothelial cells than are TH1 cells. E. TH1 cells produce interferon (IFN)- but not IL-4, and TH2 cells produce IL-4 but not IFN-
A
E. TH1 cells produce interferon (IFN)- but not IL-4, and TH2 cells produce IL-4 but not IFN-
4
Q
- The mechanisms by which TH1 cells protect against microbes include all of the following EXCEPT:
A. Secretion of interferon (IFN)-which activates microbicidal functions of macrophages
B. Expression of CD40 ligand, which binds to CD40 on macrophages and activates them
C. Secretion of IFN-, which promotes B cell production of opsonizing antibodies
D. Secretion of lymphotoxin and tumor necrosis factor, which enhance neutrophil killing of ingested microbes
E. Release of granzyme B, which stimulates apoptosis of bacteria
A
E. Release of granzyme B, which stimulates apoptosis of bacteria
5
Q
- Activated macrophages perform all of the following functions EXCEPT:
A. Inhibition of fibroblast proliferation and angiogenesis within damaged tissues
B. Production of lysosomal enzymes and reactive oxygen species that kill phagocytosed microbes
C. Presentation of antigen to helper T cells
D. Secretion of inflammatory cytokines such as tumor necrosis factor and interleukin-1
E. Production of nitric oxide, which helps kill microorganisms
A
A. Inhibition of fibroblast proliferation and angiogenesis within damaged tissues
6
Q
6. Which of the following molecules is NOT important in the interaction between a cytolytic T lymphocyte and a target cell? A. B7-1 B. ICAM-1 C. LFA-1 D. T cell receptor E. Class I MHC
A
A. B7-1
7
Q
7. Which pair of molecules is a component of cytolytic T lymphocyte (CTL) granules and is important in the mechanism of CTL killing of target cells? A. Perforin and Fas ligand B. P-selectin and tumor necrosis factor C. Major basic protein and granzyme B D. C9 and interferon- E. Perforin and granzyme B
A
E. Perforin and granzyme B
8
Q
- Which one of the following statements about primary and secondary antibody responses is NOT true?
A. Antibodies in primary responses generally have lower affinity for antigen than those produced in secondary responses.
B. Secondary responses reach peak levels more quickly than primary responses.
C. Primary responses require higher concentrations of antigen for initiation than secondary responses.
D. Primary responses occur to all types of antigens, but secondary responses mostly occur only to protein antigens.
E. Primary responses are characterized by IgG antibodies, whereas secondary responses are dominated by IgM antibodies.
A
E. Primary responses are characterized by IgG antibodies, whereas secondary responses are dominated by IgM antibodies.
9
Q
- Which one of the following statements about humoral immune responses is true?
A. Naive B cells are required for initiation of primary responses and memory B cells are required for initiation of secondary responses.
B. Antibody responses to bacterial polysaccharide antigens require CD4+ helper T cells.
C. Heavy chain isotype switching typically occurs in response to bacterial polysaccharide antigens.
D. Affinity maturation does not require helper T cells.
E. Antibody-secreting cells generated during a humoral immune response live for only a few hours.
A
A. Naive B cells are required for initiation of primary responses and memory B cells are required for initiation of secondary responses.
10
Q
- Which one of the following statements accurately describes antigen recognition events in a lymph node during a helper T cell–dependent antibody response to a protein antigen?
A. Naive B cells and naive T cells simultaneously recognize the intact protein antigen.
B. Naive B cells recognize intact proteins, generate peptide fragments of these proteins, and present them in complexes with major histocompatibility complex (MHC) molecules to naive helper T cells.
C. Naive B cells recognize intact proteins, generate peptide fragments of these proteins, and present them in complexes with MHC molecules to differentiated helper T cells.
D. Naive T cells recognize peptides bound to MHC molecules presented by dendritic cells, and naive B cells recognize the intact protein antigen bound to the surface of follicular dendritic cells.
E. Differentiated helper T cells recognize peptides bound to MHC molecules on dendritic cells, and the T cells secrete cytokines that promote antibody production by any nearby B cells that have recognized different protein antigens.
A
C. Naive B cells recognize intact proteins, generate peptide fragments of these proteins, and present them in complexes with MHC molecules to differentiated helper T cells.
11
Q
- In 1890, Emil von Behring and Shibasaburo Kitasato demonstrated the efficacy of serum transfer at conferring infection resistance—a process now known as “passive immunity.” The researchers isolated serum from animals that had recovered from infection with the diphtheria bacilli and subsequently injected the serum into other healthy animals. This procedure conferred specific resistance against the pathologic effects of diphtheria infection in the recipient animals. Which of the following immune phenomena were primarily responsible for these effects?
A. Pathogen-specific B and T cells from the original infected animals triggered a robust immune response after re-exposure to diphtheria antigens in the recipient animal.
B. Inflammatory cytokines in the transferred serum increased the strength and efficacy of innate immune system activity.
C. Diphtheria-specific antibodies in the transferred serum neutralized bacillus toxins and promoted bacterial elimination by innate effector cells.
D. Serum complement proteins in the transfer directly promoted bacterial cell lysis and phagocytosis.
E. The recipient animal’s immune response to the foreign serum further activated host immune system function, allowing greater response to the bacillus infection.
A
C. Diphtheria-specific antibodies in the transferred serum neutralized bacillus toxins and promoted bacterial elimination by innate effector cells.
12
Q
12. Which of the following anatomic regions is normally protected from pathogens only by humoral immune responses and not by cell-mediated immune responses? A. Skin B. Intestinal lumen C. Intestinal epithelium D. Central nervous system E. Spleen
A
B. Intestinal lumen
13
Q
- Up to half of the IgG found in the serum of a normal individual is produced by which of the following cells?
A. Naive B cells in lymph nodes
B. Activated B cells in the spleen
C. B cells in germinal centers of lymph nodes
D. B lymphocytes in the gastrointestinal tract
E. Long-lived plasma cells in the bone marrow
A
E. Long-lived plasma cells in the bone marrow
14
Q
- Most effective vaccines that are currently in widespread use are specific for pathogenic viruses, and the immunity induced by the vaccines is mediated largely by antibodies. Which of the following statements accurately describes the major mechanism by which these vaccine-dependent antibody responses function?
A. The antibodies bind extracellular viral particles and prevent them from infecting cells.
B. The antibodies bind to viral antigens on the surface of infected cells and promote phagocytosis of the cells.
C. The antibodies bind to viral antigens on the surface of infected cells and promote complement-mediated lysis of the cells.
D. The antibodies bind to extracellular viral particles and target Fc receptor-expressing cytolytic T lymphocytes to kill the viruses.
E. The antibodies bind to viral envelope proteins and induce signals that inhibit viral replication.
A
A. The antibodies bind extracellular viral particles and prevent them from infecting cells.
15
Q
15. Which of the following binds to and is readily phagocytosed by mononuclear phagocytes and neutrophils? A. Antigen-IgM complexes B. Bound complement protein C3b C. Free serum IgG D. IgE bound to a helminthic parasite E. Mannose-binding lectin (MBL)
A
B. Bound complement protein C3b
16
Q
- An 8-month-old boy infant with a 3-month history of recurrent upper and lower respiratory tract infections is admitted to the hospital. The physicians consider the possibility of a hereditary immune disorder and run several tests, eventually determining that the patient has undetectable levels of serum IgA. The infant is treated with strong antibiotics and recovers. Which of the following is NOT a medical problem likely to occur in this patient as he gets older?
A. Anaphylactic reactions to blood transfusions
B. Chronic gastrointestinal infections
C. Lactose and wheat gluten intolerance
D. Inflammatory skin disease
E. Recurrent nasal sinus congestion
A
D. Inflammatory skin disease
17
Q
- Which of the following statements about Ig Fc receptors is NOT true?
A. Some Fc receptors or Fc receptor–associated signaling chains contain ITAMs in their cytoplasmic tails.
B. Some Fc receptors are linked to signal transduction pathways that cause granule exocytosis.
C. There are Fc receptors specific for all common Ig isotypes.
D. Some Fc receptors with ITIMs in their cytoplasmic tails transduce inhibitory signals.
E. Fc receptor signaling may enhance generation of reactive oxygen intermediates in phagocytes.
A
C. There are Fc receptors specific for all common Ig isotypes.
18
Q
- Which of the following events initiates activation of the alternative complement pathway?
A. C1q binding to a microbial surface
B. Mannose-binding lectin (MBL) binding to a microbial surface
C. Complement receptor 1 (CR1) binding of C3b
D. Factor I cleavage of C3
E. Spontaneous cleavage of C3 to C3b
A
E. Spontaneous cleavage of C3 to C3b
19
Q
- Which of the following is NOT a property of the classical pathway C3 convertase?
A. Composed of proteolytic fragments of C4 and C2
B. Has protease activity specific for C3 to form C3b
C. Inhibited by decay acceleration factor (DAF)
D. Stabilized by C4 binding protein (C4bp)
E. Same substrate specificity as the alternative pathway C3 convertase
A
D. Stabilized by C4 binding protein (C4bp)
20
Q
- A 17-year-old boy is taken to the emergency department because of severe abdominal and lumbar pain. Physical examination reveals splenomegaly, and laboratory studies reveal hemoglobinemia and thrombocytopenia. A urine sample is remarkable for gross hemoglobinuria. The patient reports a history of bloody urine on multiple occasions in the past. Flow cytometric analysis of the patient’s red blood cells (RBC) will most likely indicate reduced or absent expression of which pair of molecules that is normally present on RBC membranes?
A. Complement receptor 1 (CR1) and CR2
B. C1 inhibitor (C1 INH) and membrane cofactor protein (MCP, CD46)
C. Decay accelerating factor (DAF, CD55) and CD59
D. C4 binding protein (C4bp) and factor H
E. Complement receptor 3(CR3) and complement receptor 4(CR4)
A
C. Decay accelerating factor (DAF, CD55) and CD59
21
Q
- All of the following are accurate statements about neonatal immunity EXCEPT:
A. Transfer of maternal IgG across the placenta is mediated by an Fc receptor structurally similar to class I MHC.
B. IgA is absorbed in the gut from breast milk and re-secreted by the infant into the bronchial mucosa.
C. IgA secretion into breast milk involves transport through breast epithelial cells, and is dependent on the poly-Ig receptor.
D. Transport of IgG across the neonatal intestinal epithelium is mediated by an Fc receptor structurally similar to class I MHC.
E. Loss of maternal antibodies is partly responsible for increased frequency of infections in infants at about 6 months of age.
A
B. IgA is absorbed in the gut from breast milk and re-secreted by the infant into the bronchial mucosa.
22
Q
- Immunologic tolerance is defined as:
A. The removal of an antigen, or the microbes expressing the antigen, by the immune system, so that the host can tolerate the infection
B. Activation of only B cells, and not T cells, on exposure to an antigen
C. Unresponsiveness of the immune system to an antigen, which is induced by previous exposure to that antigen
D. The production of memory B cells and T cells on primary exposure to an antigen, which allows the host to tolerate a secondary exposure to the antigen
E. Vaccination of individuals against particular pathogens to prevent subsequent infections
A
C. Unresponsiveness of the immune system to an antigen, which is induced by previous exposure to that antigen
23
Q
23. Failure of self-tolerance is the cause of which one of the following types of diseases? A. Allograft rejection B. Autoimmunity C. Atopy D. Anergy E. Acne
A
B. Autoimmunity
24
Q
- Which of the following statements about induction or maintenance of T cell tolerance is NOT true?
A. Central tolerance is induced when immature developing T cells in bone marrow or thymus encounter self antigens.
B. Peripheral T cell tolerance results when mature naive T cells recognize antigens without adequate B7-1– or B7-2–mediated costimulation.
C. Peripheral T cell tolerance results when T cells recognize antigen in the setting of an innate immune response to the antigen.
D. Peripheral T cell tolerance to some antigens is induced when mature T cells recognize antigen and bind B7-1 or B7-2 via the inhibitory CTLA-4 receptor.
E. Peripheral T cell tolerance to an antigen may be induced by persistent and repeated stimulation of lymphocytes by that antigen in tissues.
A
C. Peripheral T cell tolerance results when T cells recognize antigen in the setting of an innate immune response to the antigen.
25
25. Which one of the following is NOT a mechanism of T cell tolerance?
A. Inhibition of T cell activation by interleukin-12 from regulatory T cells.
B. Apoptosis induced by Fas ligand binding to Fas.
C. Anergy induced by B7-1 or B7-2 binding to CTLA-4.
D. Anergy induced by peptide-major histocompatibility complex (MHC) binding to T cell receptors (TCRs) without B7-1 or B7-2 binding to CD28.
E. TCR-mediated up-regulation of Bim or similar pro-apoptotic proteins.
Inhibition of T cell activation by interleukin-12 from regulatory T cells.
26
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26. All of the following describe features of apoptosis EXCEPT:
A. Caspase activation
B. Membrane blebbing
C. Inflammation
D. Nuclear fragmentation
E. DNA cleavage
```
C. Inflammation
27
27. Which of the following is NOT a property of regulatory T cells?
A. Interleukin-2 receptor (CD25) expression
B. Secretion of transforming growth factor-beta
C. Maturation in the thymus
D. Secretion of interferon-gamma
E. Inhibition of function of other T cells
D. Secretion of interferon-gamma
28
28. Which one of the following factors generally favors tolerance to an antigen and not stimulation of an immune response?
A. High doses of antigen
B. Short-lived persistence of antigen
C. Cutaneous portal of entry
D. Presence of adjuvant
E. Costimulator expression on antigen-presenting cells
A. High doses of antigen
29
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29. The adaptive immune system has mechanisms of homeostasis that serve to terminate immune responses and return the immune system to a basal resting state. Which of the following is LEAST likely to be involved in lymphocyte homeostasis?
A. CTLA-4
B. Fas ligand
C. CD28
D. B cell Ig Fc receptors
E. Anti-idiotypic antibodies
```
C. CD28
30
30. All of the following statements about immune responses to tumors are true EXCEPT:
A. T cells specific for tumor antigens can be found in many human tumor patients.
B. Antibodies specific for tumor antigens can be found in many human tumor patients.
C. The presence of lymphocytic infiltrates in certain tumors is associated with a better prognosis than lymphocyte-poor tumors of the same histologic type.
D. Immunodeficient individuals are more likely to develop the most common forms of cancer than are immunocompetent individuals.
E. The host immune response is usually incapable of eradicating tumors once they are established.
D. Immunodeficient individuals are more likely to develop the most common forms of cancer than are immunocompetent individuals.
31
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31. Which of the following molecules is involved in the principal mechanism by which the immune system kills tumor cells?
A. Perforin
B. Complement C3
C. IgG
D. TGF-
E. Interleukin-2
```
A. Perforin
32
32. Class I MHC-restricted T cell responses to tumors can be demonstrated in patients with various types of tumors, yet most of these tumors do not express costimulatory molecules. Which mechanism most likely explains how naive CD8+ T cells specific for antigens expressed by these tumors are stimulated to differentiate into cytolytic T lymphocytes?
A. Malignant transformation of CD8+ T cells
B. Tumor secretion of T cell–activating cytokines
C. Cross reaction of microbe-specific CD8+ T cells with tumor antigens
D. Cross priming
E. Antigenic modulation
D. Cross priming
33
33. Which of the following is NOT a mechanism by which tumors evade immune responses?
A. Decreased synthesis of TAP
B. Increased expression of glycocalyx
C. Lack of costimulatory molecule expression
D. Increased expression of TGF-
E. Increased expression of Fas
E. Increased expression of Fas
34
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34. Which of the following is a common cause of hypersensitivity diseases?
A. Failure of lymphocyte maturation
B. Treatment with corticosteroids
C. Disseminated cancer
D. Failure of self-tolerance
E. Malnutrition
```
D. Failure of self-tolerance
35
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35. Which type of hypersensitivity disease is caused by deposition of antigen-antibody complexes in blood vessel walls?
A. Type I
B. Type II
C. Type III
D. Type IV
E. Type V
```
C. Type III
36
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36. A 26-year-old African-American woman visits her physician because of a prominent rash over her nose and cheeks, which she first noticed following her return from a vacation in Jamaica. She also complains of fever, fatigue, weight loss, and joint pain over the last several months. Serologic tests are conclusive for systemic lupus erythematosus (SLE), an autoimmune disease that can manifest clinically with rashes, arthritis, glomerulonephritis, hemolytic anemia, thrombocytopenia (low platelet count), and central nervous system involvement. The principal diagnostic test result specific for this condition is a high titer of autoantibodies against which of the following?
A. Glomerular basement membrane
B. Rh blood group antigen
C. Myelin
D. Double-stranded DNA
E. IgG
```
D. Double-stranded DNA
37
37. Individuals with the class I HLA-B27 allele have a 90-fold greater chance of developing which of the following inflammatory diseases, relative to HLA-B27-negative individuals?
A. Rheumatoid arthritis
B. Ankylosing spondylitis
C. Pemphigus vulgaris
D. Diabetes mellitus type 1 (insulin dependent)
E. Multiple sclerosis
B. Ankylosing spondylitis
38
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38. An 8-year-old boy from the intermountain region of the United States is brought to the pediatrician with fever, rash, and pain in his knees and ankles. Pericarditis is evident on auscultation, and echocardiography confirms mitral valve regurgitation. Three weeks before this episode, the patient had experienced a sore throat but had not received medical attention. High titers of antistreptococcal antibodies are present in the serum. This child’s disease is a result of which one of the following phenomena?
A. Clonal anergy
B. Peripheral tolerance
C. Epitope spreading
D. Central tolerance
E. Molecular mimicry
```
E. Molecular mimicry
39
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39. A 14-year-old boy is brought to the pediatrician’s office in mid summer because of an itchy, blistering rash on his calves and forearms. The rash developed 24 hours after he returned from a weekend Boy Scout camping trip. The pediatrician suspects the lesion is caused by poison ivy. If the doctor is correct, which one of the following is NOT a prominent component in the immunologic mechanisms causing the skin lesions?
A. T cells
B. IgE-coated mast cells
C. Interferon-
D. Endothelial adhesion molecules
E. Chemokines
```
B. IgE-coated mast cells
40
Natural killer cells can kill cells opsonized with antibodies in a process
called _____________.
Antibody-dependent cellular cytotoxicity (ADCC)
41
5) ___________ and ___________ compliment activation pathways utilize
C4b2aC3b
Classical Pathway and Lectin Pathway
42
7) Signal transduction in the BCR is accomplished by _________ and
_________ when antigen receptors are _____________
Ig alpha and Ig beta when antigen receptors are crosslinked
43
10. The alternative pathway of compliment activation is initiated by
The alternative pathway of complement activation is initiated by microbes in the absence of antibody. The alternative pathway functions in innate immune responses.
44
22) Naive B cells express ______________ antigen receptors.
Naïve B lymphocytes express two classes of membrane bound antibodies, immunoglobulins M and D (IgM and IgD).
45
49) Natural killer cells can bind to antibody-opsonized cells by the
Low affinity FcyRIII (CD16) receptor for IgG.
46
Activated TH1 cells express ____ which binds to ____ on B-cells. They also produce the cytokine ___ which causes the B-cells to produce ____ antibodies.
CD40L/CD40, IFN-Gamma/IgG
47
Activated Th cells express _____________ which causes them to
____________.
IL-2
| Proliferate
48
Activated B-cells _______________.
B cell activation by antigen initiates the proliferation and differentiation of the cells and prepares them to interact with helper T lymphocytes if the antigen is a protein.
49
53) The development of tolerance results from ________________.
developing lymphocytes encounter these antigens in the generative (central) lymphoid organs, a process called central tolerance, or when mature lymphocytes encounter self antigens in peripheral (secondary) lymphoid organs or peripheral tissues, called peripheral tolerance.
