Deck 9: Immunity Mediated by B Cells and Antibodies

Question 1

primary focus of B-cell expansion forms in the _____,whereas a secondary focus of B-cell expansion creates the _____.

A)T-cell area; medullary cords
B)medullary cords; T-cell area
C)T-cell area; B-cell area
D)medullary cords; germinal center
E)light zone; dark zone.

Answer 1

D

Question 2

Which of the following is not a function of antibodies?

A)They neutralize pathogens by masking their surface.
B)They act as molecular adaptors that bridge together pathogen and phagocyte surfaces.
C)They exert toxic effects directly.
D)They act as opsonins that mediate phagocytosis.
E)They activate complement fixation.

Answer 2

C

Question 3

Which of the following is an accurate description of how centroblasts differ from centrocytes?

A)Centroblasts cease their expression of cell-surface immunoglobulins.
B)Centroblasts divide more slowly than centrocytes.
C)Centroblasts express CD44 but centrocytes do not.
D)Centrocytes,but not centroblasts,initiate the process of isotype switching.
E)Centroblasts participate in affinity maturation.

Answer 3

A

Question 4

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
E)antigen-specific T_FH cells.

Question 5

mount the most effective antibody response that results in the synthesis of high-affinity antibodies,which of the following must occur? (Select all that apply.)
a.recognition of thymus-independent (TI)antigens
b.isotype switching
c.increased expression of TLR9 by B cells
d.affinity maturation
e.decreased expression of CD40 by B cells.

Question 6

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.

Question 7

Immunoreceptor tyrosine-based activation motifs (ITAMs)are located on _____.

A)the cytoplasmic tails of IgM
B)tyrosine kinases Blk,Fyn,and Lyn
C)the cytoplasmic tails of Igα and Igβ
D)breakdown products of C3b deposited on pathogen surfaces
E)thymus-independent antigens.

Question 8

Which of the following statements is true regarding the complement component C4B?

A)Deficiency of C4B is associated with systemic lupus erythematosus (SLE).
B)C4B has similar properties to those of C4A.
C)The thioester bond of C4B is preferentially acted upon by amino groups of macromolecules.
D)C4B is encoded in the class II region of the MHC.
E)The gene for C4B is duplicated or deleted in some individuals.

Question 9

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-x_L.
C)They process antigen and present it to T_FH cells.
D)CD40 on the centrocyte engages with CD40 ligand on T_FH cells.
E)They undergo phagocytosis by tingible body macrophages.

Question 10

a centrocyte does not interact with antigen and engage CD40 shortly after its derivation,then _____.

A)it recommences somatic hypermutation
B)it undergoes apoptosis
C)it moves back into the dark zone of the germinal center and switches its isotype
D)its surface immunogloblulin levels decrease and proliferation recommences.

Question 11

Lymphoblasts upregulate a transcription factor called _____ when they terminally differentiate into plasma cells.

A)NFκB
B)Bcl-x_L
C)B-lymphocyte induced maturation protein 1 (BLIMP-1)
D)CD40
E)ICAM-1.

Question 12

primary focus of clonal expansion is best described as _____.

A)the location in the B-cell zone where conjugate pairs of B and T cells undergo cellular proliferation,isotype switching,and somatic hypermutation
B)the location in the medullary cords where conjugate pairs of B cells and T cells undergo cellular proliferation and IgM is secreted
C)the dark zone of the germinal center where centroblasts divide and pack closely together
D)the initial wave of B-cell proliferation induced by T-independent antigens.

Question 13

Plasma cells and memory B cells differentiate most immediately from _____.

A)centrocytes
B)centroblasts
C)B-1 cells
D)IgG-secreting B cells.

Question 14

_____ in the switch regions positioned 5′ to each heavy-chain C gene is induced by _____.

A)Somatic hypermutation; TI antigens
B)Chromatin remodeling; B-cell co-receptor signaling
C)Recombination; survival signals received from follicular dendritic cells
D)Transcription; helper T-cell cytokines
E)Gene repression; apoptotic signals received from tingible body macrophages.

Question 15

Proliferating centroblasts use the DNA-modifying enzyme activation-induced cytidine deaminase for ________.(Select all that apply.)

A)cell proliferation
B)somatic hypermutation
C)apoptosis
D)upregulation of CD40
E)isotype switching.

Question 16

main function of Bcl-x_L 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.

Question 17

_____ is a mechanism that drives the preferential selection of immunoglobulins with the highest affinity for antigen.

A)Anergy
B)Isotype-switching
C)Affinity maturation
D)Antibody-dependent cell-mediated cytotoxicity
E)Transcytosis.

Question 18

primary focus forms after a circulating naive B cell forms a conjugate pair with _____ in the _____ of a lymph node.

A)T_H1 cell; B-cell zone
B)cytotoxic T cell; T-cell zone
C)follicular dendritic cell; germinal center
D)T_FH; medullary cords
E)CD40 ligand; T-cell zone.

Question 19

Describe the ways in which follicular dendritic cells (FDCs)are similar to subcapsular sinus macrophages.

Question 20

Explain why expression of CD40 ligand by T_FH cells is important in the boundary area of primary follicles in secondary lymphoid tissue as it relates to the targeted delivery of secreted cytokines to the B-cell surface.

Question 21

B-cell co-receptor is composed of

A)Igα; Igβ; CD19
B)Igα; Igβ; Lyn tyrosine kinase
C)CR2 (CD21); CD19; CD81
D)CD14; CD19; CD81
E)CD40; MHC class II; CED19.

Question 22

does IgE induce the forcible ejection of parasites and toxic substances from the respiratory and gastrointestinal tracts?

Question 23

Explain how the poly-Ig receptor transports dimeric IgA antibodies across cellular barriers,and specify the type of cell barrier involved.
B.What are the final locations of the transported material?

Question 24

types of B-cell tumor have been treated with rituximab,an anti-CD20 monoclonal antibody,which exerts its effect through a mechanism known as ______ involving the participation of NK cells.

A)degranulation
B)neutralization
C)opsonization
D)antibody-dependent cell-mediated cytoxicity
E)receptor-mediated endocytosis.

Question 25

IgG2 to be effective at stimulating uptake of IgG2-coated bacteria,_____.

A)an individual must express allotype H131 of FcγRIIA
B)an individual must express allotype R131 of FcγRIIA
C)the ITIMs of FcγRIIB2 must be non-functional
D)complement must be fixed on the surface of the bacterium.

Question 26

What are the similarities between the activation of mast cells and NK cells via FcεRI and FcγRIII,respectively? Be specific.
B.What are the differences? Again,be specific.

Question 27

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.

Question 28

Which of the following is a characteristic of follicular dendritic cells in the primary follicles of secondary lymphoid tissues? (Select all that apply.)

A)They are bone marrow derived hematopoietic cells.
B)They provide a stable depository of intact antigens able to bind to B-cell receptors.
C)They have a large surface area as a result of forming dendrites.
D)They internalize immune complexes through CR2 receptor cross-linking.
E)They produce cytokines that induce B cells to proliferate and become centroblasts.

Question 29

distinguishing feature of FcγRIIB1 compared with FcγRIIA is _____.

A)its ability to activate cells and induce endocytosis
B)the existence of ITIMs in its cytoplasmic tails
C)its inability to bind to IgG1
D)its expression on NK cells.

Question 30

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.

Question 31

is particularly efficient at fixing complement because it _____.

A)is a much larger antibody than the other isotypes
B)has an extra C_H domain
C)is made first in an immune response and therefore has first access to C1q
D)has five binding sites for C1q
E)has easy access to extravascular areas.

Question 32

Explain the origin of the secretory component and its significance after the release of dimeric IgA from the apical face of the gut epithelium.

Question 33

Describe the course of events that results in the swollen lymph nodes characteristic of many infections.Use the following terms in your

Question 34

What is meant by the term "passive transfer of immunity," and how is it achieved? Give examples.
B.Give the isotype of the antibodies involved in (i)placental transfer and (ii)transfer into breast milk,and explain why these antibodies are important.
C.Do you think it is possible for a pregnant mother who has an autoimmune disease to transfer autoreactive antibodies to the developing fetus? Explain your answer.

Question 35

What is the main effector function of IgM antibody?
B.Why is IgM efficient at (i)preventing blood-borne infections and (ii)fixing complement,but (iii)less efficient than other antibody classes in inducing phagocytosis of immune complexes?

Question 36

Naive B cells search for specific antigen displayed by follicular dendritic cells in primary follicles.Naive T cells,however,search for specific antigen presented by ______.

A)dendritic cells
B)subcapsular sinus macrophages
C)medullary sinus macrophages
D)centrocytes
E)tingible body macrophages.

Question 37

Which of the following is consistent with a recently antigen-activated mast cell?

A)high levels of MHC class II molecules on the cell surface
B)the absence of prepackaged granules
C)the absence of IgE on the cell surface
D)high concentrations of C3b on the cell surface
E)the induction of antibody-dependent cell-mediated cytotoxicity.

Question 38

an immunological viewpoint,why would it be inadvisable for a mother who has recently given birth to move with her newborn to a foreign country where there are endemic diseases not prevalent in her homeland?

Question 39

γ chain of the FcγRI receptor is closely related to the _____,which contains _____.

A)FcRn; MHC class I-like structure
B)ζ chain of the T-cell receptor complex; ITAM motifs
C)γ chain of the FcγRIII receptor; ITIM motifs
D)γ chain of the FcαRI receptor; ITIM motifs
E)γ chain of the FcεRI receptor; ITIM motifs.

Question 40

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.

Question 41

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.

Question 42

_____ occurs as a result of influenza virus binding to oligosaccharide components on erythrocyte surfaces causing them to clump together.

A)Passive immunization
B)Opsonization
C)Hemagglutination
D)Neutralization
E)Complement activation.

Question 43

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.

Question 44

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.

Question 45

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.

Question 46

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.

Question 47

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.

Question 48

symptoms of allergy and asthma are induced after cross-linking of IgE antibody on FcεRI receptors found on the surface of _____.(Select all that apply.)

A)basophils
B)eosinophils
C)macrophages
D)mast cells
E)neutrophils.

Question 49

B cell's sensitivity to antigen can be increased 1000-10,0000-fold by

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-α ITAMs
D)increasing levels of Syk proteins in the vicinity of co-receptor ligation
E)ligating cytokine receptors on the B-cell surface.

Question 50

disadvantage of having a longer hinge region in IgG3 compared with the 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.

Question 51

Bacteria use _____ to attach to the surface of cells during colonization.

A)hemagglutinins
B)toxins
C)breakdown products
D)anti-inflammatory molecules
E)adhesins.

Question 52

Which of the following antibodies activate the classical pathway of complement? (Select all that apply.)

A)IgM
B)IgG1
C)IgD
D)IgG3
E)IgE.

Question 53

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.

Question 54

the following,which group of children is the most vulnerable to infection?

A)babies born at term
B)babies born prematurely
C)infants of 3-6 months
D)infants receiving first vaccination
E)babies receiving formula and not breast milk.

Question 55

the Fc receptors for IgG,which one is similar to FcεRI in its ability to bind antibody in the absence of antigen but does not transduce an activating signal until antigen cross-linking occurs?

A)FcγRI
B)FcγRIIA
C)FcγRIIB2
D)FcγRIIB1
E)FcγRIII.

Question 56

Antibody-dependent cell-mediated cytotoxicity (ADCC)is carried out by _____ after cross-linking of IgG1 or IgG3 antibodies on _____ receptors.

A)NK cells; FcγRI
B)neutrophils; FcγRI
C)NK cells; FcγRIII
D)macrophages; FcγRIIB2
E)mast cells; FcεRI.

Question 57

Igα-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.

Question 58

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.

Question 59

FcαRI receptor binds to _____:antigen complexes and facilitates the phagocytosis of opsonized antigens.

A)dimeric IgA
B)IgM
C)IgE
D)IgG
E)monomeric IgA.
ANSWERS