CHAPTER 9
Immunity Mediated by B Cells and Antibodies
Questions
9–1
The B-cell co-receptor is composed of
a. Ig; Ig; CD19
b. Ig; Ig; Lyn tyrosine kinase
c. CR2 (CD21); CD19; CD81
d. CD14; CD19; CD81
e. CD40; MHC class II; CED19.
9–2
C3d and iC3b are breakdown products of _____ which binds to _____ of the B-cell co-receptor.
a. C3a; CR2
b. C3b; CR2
c. C3c; CD81
d. C3c; CD19
e. C3b; CD19.
9–3
When bound to CR1, C3b is cleaved by _____, generating pathogen-associated B-cell co-
receptor ligands.
a. factor I
b. CR2
c. C3d
d. CD19
e. Lyn.
9–4
The Ig-associated tyrosine kinase _____ phosphorylates the cytoplasmic tail of CD19, which
mediates signal transduction in activated B cells.
a. CD81
b. Blk
c. Fyn
d. Lyn
e. Syk.
9–5
A B cell’s sensitivity to antigen can be increased 1000–10,000-fold by
2
a. simultaneously ligating the B-cell receptor and co-receptor
b. simultaneously ligating the B-cell receptor and Toll-like receptor
c. ligating the B-cell co-receptor and phosphorylating Ig- ITAMs
d. increasing levels of Syk proteins in the vicinity of co-receptor ligation
e. ligating cytoine receptors on the B-cell surface.
9–6
Lipopolysaccharide is an example of a _____ antigen that is recognized by TLR4 when bound to
_____.
a. thymus-independent (TI)-1; LPS-binding protein
b. thymus-dependent; MHC class II
c. thymus-independent (TI)-2; B-cell co-receptor
d. thymus-dependent; LPS-binding protein
e. immune complex; iccosomes.
9–7
Which of the following describes thymus-independent (TI)-2 antigens? (Select all that apply.)
a. They induce a late antibody response that is predominantly IgG.
b. They induce high-affinity antibodies through somatic hypermutation.
c. They induce long-term immunological memory.
d. They contain repetitive epitopes on the surface of microorganisms.
e. They cause dense cross-linking of B-cell receptors and co-receptors, leading to B-cell
proliferation and differentiation.
9–8
Which of the following is true of TLR9? (Select all that apply.)
a. It binds to LPS.
b. It binds to bacterial DNA.
c. It is located in endocytic vesicles.
d. It binds to repetitive carbohydrate epitopes.
e. It binds to repetitive protein epitopes.
9–9
A primary focus forms after a circulating naive B cell forms a conjugate pair with _____ in the
_____ of a lymph node.
a. TH1 cell; B-cell zone
b. cytotoxic T cell; T-cell zone
c. follicular dendritic cell; germinal center
d. TH2 cell; T-cell zone
e. CD40 ligand; T-cell zone.
9–10
Which of the following molecules bind(s) to components found on the surface of an activated B
cell? (Select all that apply.)
a. MHC class II
b. T-cell receptor
3
c. antigen
d. CD40
e. C3d
f. IL-4
g. CD4
h. LFA-1
i. CD40 ligand.
9–11
B cells migrating directly from a primary focus to the medullary cords in a lymph node after
activation with a T-dependent antigen differentiate into plasma cells that secrete predominantly
_____.
a. IgD
b. IgE
c. sIgA
d. IgG
e. IgM.
9–12
Lymphoblasts upregulate a transcription factor called _____ when they terminally differentiate
into plasma cells.
a. NFB
b. Bcl-xL
c. B-lymphocyte induced maturation protein 1 (BLIMP-1)
d. CD40
e. ICAM-1.
9–13
Follicular dendritic cells (FDCs) carry the receptors FcR and CR2, which bind IgG and
complement components (C3b and C3d), respectively, when bound to antigen in the form of
immune complexes.
A. How would an immune complex containing IgM bind to FDCs?
B. Unlike the same receptors on macrophages, the FcR and complement receptors on FDCs
are not internalized by receptor-mediated endocytosis when occupied by immune
complexes. How does this enable FDCs to carry out their function? Comment briefly on
the consequence of these different properties of macrophages and FDCs for the immune
response.
9–14
A primary focus of B-cell expansion forms in the _____, whereas a secondary focus of B-cell
expansion forms in the _____.
a. T-cell zone; medullary cords
b. medullary cords; T-cell zone
c. T-cell zone; B-cell zone
d. medullary cords; germinal center
e. light zone; dark zone.
4
9–15
For which process do proliferating centroblasts use the DNA-modifying enzyme activation-
induced cytidine deaminase? (Select all that apply.)
a. cell proliferation
b. somatic hypermutation
c. apoptosis
d. upregulation of CD40
e. isotype switching.
9–16
What is the fate of centrocytes in which somatic hypermutation has resulted in high-affinity
receptors for antigen? (Select all that apply.)
a. They die by apoptosis.
b. They express Bcl-xL.
c. They process antigen and present it to TH2 cells.
d. CD40 on the centrocyte engages with CD40 ligand on TH2 cells.
e. Phagocytosis by tingible body macrophages.
9–17
In secondary lymphoid tissues, which of the following routes do B cells take during their
activation, proliferation and differentiation?
a. HEV → T-cell zone → medullary cords → dark zone of germinal center → light zone of
germinal center
b. HEV → B-cell zone → T-cell zone → medullary cords → light zone of germinal center
c. HEV → T-cell zone → dark zone of germinal center → light zone of germinal center →
medullary cords
d. HEV → medullary cords → T-cell zone → dark zone of germinal center → light zone of
germinal center
e. HEV → dark zone of germinal center → light zone of germinal center → T-cell zone →
medullary cords.
9–18
The main function of Bcl-xL is to _____ in the centrocyte.
a. provide death signals
b. induce somatic hypermutation
c. upregulate the expression of activation-induced cytidine deaminase
d. prevent apoptosis
e. induce isotype switching.
9–19
Engulfment of apoptotic centrocytes is facilitated by _____ in germinal centers.
a. follicular dendritic cells
b. immune-complex coated bodies (iccosomes)
c. tingible body macrophages
d. antigen-specific B cells
5
e. antigen-specific TH2 cells.
9–20
The process that drives an increase in antibody affinity for antigen is known as _____.
a. apoptosis
b. affinity maturation
c. antibody-dependent cell-mediated cytotoxicity
d. opsonization
e. clonal expansion.
9–21
Select the correctly matched human cytokine; consequence pair. (Select all that apply.)
a. IL-4; memory B cell
b. IFN-; IgG1
c. IL-5; apoptosis
d. TGF-; B-1 lineage activation
e. IL-10; plasma cell.
9–22
FcRn has which of the following characteristics? (Select all that apply.)
a. It binds to monomeric IgA in acidified endocytic vesicles.
b. It transports IgG out of the blood into tissue across the endothelium.
c. It is similar in structure to an MHC class II molecule.
d. It protects IgA from degradation by plasma proteases.
e. Two molecules of FcRn are required to bind to each Fc region.
9–23
Match the receptor with its description.
Receptor:
____ a. poly-Ig receptor
____ b. FcRIII (CD16)
____ c. FcRI
____ d. FcRn
____ e. B-cell co-receptor
____ f. FcRII-B1 (CD32).
Description:
i. transport of IgG out of the bloodstream to extracellular spaces in tissues
ii. facilitation of antibody-dependent cell-mediated cytotoxicity in NK cells
iii. cross-linking of antibody:antigen complexes on mast cells, followed by degranulation
iv. binding to dimeric IgA and facilitation of its transcytosis
v. CD21/CD19/CD81
vi. inhibition of B-cell activation.
9–24
6
Mucosal epithelia of the gastrointestinal tract, eyes, nose, throat, the respiratory, urinary, and
genital tracts, and the mammary glands are protected by
a. IgG
b. IgM
c. IgE
d. monomeric IgA
e. dimeric IgA.
9–25
The process involving receptor-mediated transport of macromolecules from one side of a cell to
the other is called
a. phagocytosis
b. exocytosis
c. transcytosis
d. signal transduction
e. opsonization.
9–26
The poly-Ig receptor on the basolateral surface of epithelial cells binds to _____ via the _____.
(Select all that apply.)
a. dimeric IgA; J chain
b. monomeric IgA; J chain
c. monomeric IgA; CH2 domain
d. IgM; J chain
e. IgG; CH3 domain.
9–27
Which of the following are examples of passive transfer of immunity? (Select all that apply.)
a. antibody production after vaccination
b. transplacental acquisition of IgG during fetal development
c. provision of IgA through breast milk
d. antibody production after an influenza infection
e. intravenous immunoglobulin therapy for immunocompromised individuals
f. receiving antivenom after being bitten by a poisonous snake.
9–28
Of the following, which group of children is the most vulnerable to infection?
a. babies born at term
b. babies born prematurely
c. infants aged 3–6 months
d. infants receiving first vaccination
e. babies receiving formula and not breast milk.
9–29
_____ occurs as a result of influenza virus binding to oligosaccharide components on erythrocyte
surfaces causing them to clump together.
7
a. Passive immunization
b. Opsonization
c. Hemagglutination
d. Neutralization
e. Complement activation.
9–30
Which of the following are correctly matched? (Select all that apply.)
a. protein F; fibronectin
b. neutralization; IgE
c. breast milk; IgG
d. influenza; hemagglutinin
e. mucosal epithelium; IgA.
9–31
Bacteria use _____ to attach to the surface of cells during colonization.
a. hemagglutinins
b. toxins
c. breakdown products
d. anti-inflammatory molecules
e. adhesins.
9–32
Denatured toxin molecules called _____ are used to vaccinate individuals to stimulate the
production of _____.
a. toxoids; neutralizing IgG antibodies
b. adhesins; neutralizing antibodies
c. toxoids; passive immunity
d. adhesins; complement proteins
e. toxoids; C-reactive protein.
9–33
Which of the following is able to bind to C1q? (Select all that apply.)
a. bacterial adhesins
b. toxoids
c. IgM
d. C-reactive protein
e. hemagglutinin
f. lipopolysaccharide
g. classical C3 convertase.
9–34
IgM is particularly efficient at fixing complement because _____.
a. it is a much larger antibody than the other isotypes.
b. it has an extra CH domain.
c. it is made first in an immune response and therefore has first access to C1q.
8
d. it has five binding sites for C1q.
e. it has easy access to extravascular areas.
9–35
C3 convertase of the classical pathway is _____, whereas C3 convertase of the alternative
pathway is _____.
a. C1a; C3bBb
b. C4bC2a; C3bBb
c. C3bCR1; C3bBb
d. C4bC2a; C3bCR1
e. C1a; C3bCR1.
9–36
Which of the following statements are true regarding C4? (Select all that apply.)
a. There are two forms of C4 encoded by separate genes residing in the class II region of the
MHC.
b. Evolution of the different forms of C4 probably occurred as a result of gene duplication
and diversification.
c. Because there are two forms of C4, C4 deficiency is the least common human
immunodeficiency.
d. More than 30% of the human population lacks either C4A or C4B.
e. C4A and C4B have identical properties.
f. C4B deficiency is associated with increased susceptibility to systemic lupus
erythematosus.
g. C4A and C4B are monomorphic.
9–37
Complexes of IgG bound to soluble multivalent antigens can activate the classical pathway of
complement, resulting in the deposition of _____ on the complex, targeting it for endocytic
uptake by cells bearing _____.
a. C4b; CR2 and Fc receptors
b. C3b; CR2 and Toll-like receptors
c. C5-9; CR1 and Fc receptors
d. C3b; CR1 and Fc receptors
e. C2a; CR2 and Toll-like receptors.
9–38
Which of the following are characteristics of systemic lupus erythematosus? (Select all that
apply.)
a. It is an autoimmune disease.
b. It is associated with a deficiency of C4A.
c. Increased levels of immune complexes are detected in the blood.
d. CR1 receptor levels are decreased.
e. Immune complexes are deposited on the kidney glomeruli, which can lead to kidney
complications.
9
9–39
The disadvantage of having a longer hinge region in IgG3 than the in other IgG subclasses is a
reduction in its serum half-life because of its susceptibility to _____.
a. increased proteolysis by serum proteases
b. clearance by erythrocytes via FcR binding
c. immune complex formation and deposition in kidney glomeruli
d. complement fixation and uptake by cells bearing receptor CR1
e. opsonization by neutrophils.
9–40
The advantage of having a longer hinge region in IgG3 than in the other IgG subclasses is _____.
(Select all that apply.)
a. most efficient neutralization ability
b. greater flexibility in antigen binding
c. ability to form aggregates and thereby increase the number of antigen-binding sites
d. most efficient complement activation
e. greater accessibility of Fc for binding to C1.
9–41
Which of the following antibodies activate the classical pathway of complement? (Select all that
apply.)
a. IgM
b. IgG1
c. IgG2
d. IgG3
e. IgG4.
9–42
Which of the following antibodies exhibits monovalence as a result of the exchange of IgG half-
molecules (one H plus one L chain) forming bispecific antibody molecules?
a. IgM
b. IgG1
c. IgE
d. dimeric IgA
e. IgG4.
9–43
The chain of the FcRI receptor is closely related to the _____, which contains _____.
a. FcRn; MHC class I-like structure
b. chain of the T-cell receptor complex; ITAM motifs
c. chain of the FcRIII receptor; ITIM motifs
d. chain of the FcRI receptor; ITIM motifs
e. chain of the FcRI receptor; ITIM motifs.
9–44
10
Of the Fc receptors for IgG, which one is similar to FcRI in its ability to bind antibody in the
absence of antigen but does not transduce an activating signal until antigen cross-linking has
occurred?
a. FcRI
b. FcRIIA
c. FcRIIB2
d. FcRIIB1
e. FcRIII.
9–45
Which of the following individuals would be most susceptible to fulminant meningococcal
disease or septic shock when infected with Neisseria meningitidis?
a. homozygous for allotype H131 of IgG2
b. heterozygous for allotype H131 of IgG2
c. homozygous for allotype R131 of IgG2
d. heterozygous for allotype R131 of IgG2.
e. All of the above would be equally susceptible to infections with Neisseria meningitidis
9–46
Antibody-dependent cell-mediated cytotoxicity (ADCC) is carried out by _____ after cross-
linking of IgG1 or IgG3 antibodies on _____ receptors.
a. NK cells; FcRI
b. neutrophils; FcRI
c. NK cells; FcRIII
d. macrophages; FcRIIB2
e. mast cells; FcRI.
9–47
The symptoms of allergy and asthma are induced after cross-linking of IgE antibody on FcRI
receptors found on the surface of _____. (Select all that apply.)
a. basophils
b. eosinophils
c. macrophages
d. mast cells
e. neutrophils.
9–48
The FcRI receptor binds to _____–antigen complexes and facilitates the phagocytosis of
opsonized antigens.
a. dimeric IgA
b. IgM
c. IgE
d. IgG
e. monomeric IgA.
11
Answers
12
13