Question 1

Which of the following is NOT a property of the classical pathway C3 convertase?

Accepted Answer

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) 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 D

Question 2

All of the following are accurate statements about neonatal immunity EXCEPT:

Accepted Answer

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) 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. B

Question 3

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?

Accepted Answer

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) Anaphylactic reactions to blood transfusions 
B) Chronic gastrointestinal infections 
C) Lactose and wheat gluten intolerance 
D) Inflammatory skin disease 
E) Recurrent nasal sinus congestion D

Question 4

Which of the following statements about Ig Fc receptors is NOT true?

Accepted Answer

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) 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.

Question 5

Up to half of the IgG found in the serum of a normal individual is produced by which of the following cells?

Accepted Answer

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) 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

Question 6

Which of the following anatomic regions is normally protected from pathogens only by humoral immune responses and not by cell-mediated immune responses?

Accepted Answer

A) Skin 
B) Intestinal lumen 
C) Intestinal epithelium 
D) Central nervous system 
E) Spleen 
A) Skin 
B) Intestinal lumen 
C) Intestinal epithelium 
D) Central nervous system 
E) Spleen

Question 7

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?

Accepted Answer

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) 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)

Question 8

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?

Accepted Answer

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) 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.

Question 9

Which of the following statements about C3 is NOT correct?

Accepted Answer

A) C3 contains an internal thioester bond that participates in covalent linkage to cell surfaces. 
B) C3 is the most abundant complement protein in the serum. 
C) A proteolytic fragment of C3 is part of both the C3 and C5 convertases. 
D) Activated C3 is a serine protease that cleaves C4. 
E) C3 in the plasma is spontaneously cleaved into C3b. 
A) C3 contains an internal thioester bond that participates in covalent linkage to cell surfaces. 
B) C3 is the most abundant complement protein in the serum. 
C) A proteolytic fragment of C3 is part of both the C3 and C5 convertases. 
D) Activated C3 is a serine protease that cleaves C4. 
E) C3 in the plasma is spontaneously cleaved into C3b.

Question 10

Treatment of antibodies with the enzyme papain under conditions of limited proteolysis results in hinge-region cleavage, yielding monovalent antigen-binding Fab fragments that lack a constant region. Which effector function of antibodies would Fab fragments be able to perform?

Accepted Answer

A) Complement pathway activation 
B) Antibody-dependent cell-mediated cytotoxicity 
C) Opsonization 
D) Antigen cross-linking and precipitation 
E) Microbe neutralization 
A) Complement pathway activation 
B) Antibody-dependent cell-mediated cytotoxicity 
C) Opsonization 
D) Antigen cross-linking and precipitation 
E) Microbe neutralization

Question 11

Which of the following events initiates activation of the alternative complement pathway?

Accepted Answer

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) 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

Question 12

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?

Accepted Answer

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) 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.

Question 13

A 15-year-old girl is brought to a pediatric clinic with severe abdominal pain, nausea, and vomiting. She does not have a fever, peritoneal signs, or an elevated white blood cell count. The symptoms resolve in 48 hours. She has a history of multiple transient episodes of facial edema without pruritus. Laboratory examination is most likely to reveal which of the following abnormalities in this patient?

Accepted Answer

A) C4 deficiency 
B) Reduced levels of C1 inhibitor (C1 INH) 
C) Absence of C3 
D) Presence of C3 nephritic factor 
E) Deficiency of factor I 
A) C4 deficiency 
B) Reduced levels of C1 inhibitor (C1 INH) 
C) Absence of C3 
D) Presence of C3 nephritic factor 
E) Deficiency of factor I

Which of the following is NOT a property of the classical pathway C3 convertase?

All of the following are accurate statements about neonatal immunity EXCEPT:

Which of the following statements about Ig Fc receptors is NOT true?

Up to half of the IgG found in the serum of a normal individual is produced by which of the following cells?

Which of the following anatomic regions is normally protected from pathogens only by humoral immune responses and not by cell-mediated immune responses?

Which of the following statements about C3 is NOT correct?

Treatment of antibodies with the enzyme papain under conditions of limited proteolysis results in hinge-region cleavage, yielding monovalent antigen-binding Fab fragments that lack a constant region. Which effector function of antibodies would Fab fragments be able to perform?

Which of the following events initiates activation of the alternative complement pathway?

Introduction to the Immune System

Innate Immunity

Antigen Capture and Presentation to Lymphocytes

Antigen Recognition in the Adaptive Immune System

T Cell–Mediated Immunity

Effector Mechanisms of T Cell–Mediated Immunity

Humoral Immune Responses

Immunological Tolerance and Autoimmunity

Immune Responses against Tumors and Transplants

Hypersensitivity

Congenital and Acquired Immunodeficiencies

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Exam 8: Effector Mechanisms of Humoral Immunity

Which of the following is NOT a property of the classical pathway C3 convertase?

All of the following are accurate statements about neonatal immunity EXCEPT:

Which of the following statements about Ig Fc receptors is NOT true?

Up to half of the IgG found in the serum of a normal individual is produced by which of the following cells?

Which of the following anatomic regions is normally protected from pathogens only by humoral immune responses and not by cell-mediated immune responses?

Which of the following statements about C3 is NOT correct?

Treatment of antibodies with the enzyme papain under conditions of limited proteolysis results in hinge-region cleavage, yielding monovalent antigen-binding Fab fragments that lack a constant region. Which effector function of antibodies would Fab fragments be able to perform?

Which of the following events initiates activation of the alternative complement pathway?

Introduction to the Immune System

Innate Immunity

Antigen Capture and Presentation to Lymphocytes

Antigen Recognition in the Adaptive Immune System

T Cell–Mediated Immunity

Effector Mechanisms of T Cell–Mediated Immunity

Humoral Immune Responses

Immunological Tolerance and Autoimmunity

Immune Responses against Tumors and Transplants

Hypersensitivity

Congenital and Acquired Immunodeficiencies

Filters