Chapter 4: 4-1 through 4-17 Flashcards
What cell produces antibodies once it is activated?
Plasma cells “effector B cells”
How is a B cell activated?
binds an antigen, presents to T-cell, Helper T cells stimulates plasma cell to make antibodies that will then tag the antigen for pickup by macrophages or other types of phagocytes.
Which of the immunoglobulin isotypes would be most important for neutralizing polio virus before it could infect intestinal cells? A. secretory IgA B. serum IgA C. serum IgD D. secretory IgG E. Membrane IgM
secretory IgA
What are the regions of the antibody contributes MOST to the affinity of the antibody for antigen? A. CDR B. Fab C. Fc D. hinge region E. loops in the Fc region
CDR
What factor or structural element of a antibody determines its isotype form?
A. antigen specificity
B. Heavy chain constant region
C. Light chain constant region
D. number of antigen binding sites
E. number of Variable and constant domains
Heavy chain constant region
The _______ contribute to antigen specificity of immunoglobulins, and _______ make up the more conservative flanking regions:
A. hypervariable loops; framework regions
B. constant domains; variable domains
C. heavy chains; light chains
D. variable gene segments; joining gene segments
hypervariable loops; framework regions
The derivation of antibodies from a single clone of B lymphocytes that have identical antigen specificity.
Monoclonal antibody production
Change of immunoglobulin class but preservation of antigen specificity
isotype switching
Nucleotide changes in variable regions of immunoglobulin genes affecting affinity for antigen.
somatic hypermutation
Enhancement of receptor-mediated phagocytosis of immunoglobulin-coated antigen.
opsonization
The rearrangement of V, D, and J segments to form an immunoglobulin.
somatic recombination
Which immunoglobulin’s main function is to mediate A. IgA B. IgD C. IgE D. IgG E. IgM
IgE
The antigen-binding site of an immunoglobulin is formed from…
A. the V regions of light chains only
B. the C regions of heavy chains only
C. paired V regions of a single heavy chain and a single light chain
D. paired V regions of two light chains
E. paired C regions of two heavy chains
C. paired V regions of a single heavy chain and a single light chain
When IgG is cleaved with a protease that targets a hinge region, which of the following is generated?
A. two Fab fragments and one Fc fragment
B. two Fc fragments and two Fab fragments
C. Fc fragments that bind antigen
D. Fab fragments that facilitate antibody effector function
E. a membrane-bound form of antibody
A. two Fab fragments and one Fc fragment
The part of the antibody that binds antigen
V domain
Contributes around 50 kDa to the overall molecular weight of IgG
heavy chain
Comprises the beta strands and loops not involved in antigen binding
framework region
The most conserved region of the molecule with limited variation between antibodies
constant region
Pairs with the amino-terminal part of a heavy chain to form one of the two arms of an antibody
light chain
A protein epitope formed as a result of three-dimensional folding of the protein, and which is destroyed if the protein denatures, is called a \_\_\_\_\_\_\_ epitope. A. linear B. multivalent C. conformational D. complementarity E. framework
C. conformational
The numbered events listed below participated in the generation of junctional diversity. Put them in chronological order.
A. DNA strands pair, and unpaired nucleotides are removed by exonuclease activity.
B. P-nucleotides are generated after nicking of one DNA strand
C. DNA polymerase fills in gaps, and DNA ligation forms a coding joint
D. The RAG complex cleaves heptamer RSSs, and DNA hairpins are formed.
E. Terminal deoxynucleotidyl transferase adds N-nucleotides to the 3 prime end of the stretch of P-nucleotides.
D, B, E, A, C
Which of the following statements regarding the process of differential splicing of primary RNA transcripts encoding immunoglobulins is incorrect?
A. It does not require rearrangement of genomic DNA sequences.
B. It underlies the production of both membrane-bound IgM and IgD in naïve B cells.
C. It is the mechanism involved in isotype switching.
D. It occurs during B-cell differentiation into plasma cells when antibodies are produced in their secreted form.
E. It permits the production of different types of protein originating from the same RNA transcript.
C. It is the mechanism involved in isotype switching.
located within a V domain and varies greatly between different antibodies
hypervariable region
4-7 Which of the following recombinations is not permitted during somatic recombination in the heavy-chain and light-chain immunoglobulin loci? (select all that apply) A. Dh:Jh B. Vlambda: Jlambda C. Dk:Vh D. Vh; Jh E. Vh: Dh
C. Dk:Vh
D. Vh; Jh
4-8 Which of the following does not contribute to generating the diversity of antigen-binding specificites amoung immunoglobulins?
A. somatic hypermutation
B. random combination of heavy and light chains
C. somatic recombination
D. activation-induced cytidine deaminase (AID)
E. alternative splicing of heavy-chain RNRA transcripts.
E. alternative splicing of heavy-chain RNRA transcripts.
4-9 The phenomenon of allelic exclusion ensures that B cells…
A. use only one V, D, and J segment during somatic recombination.
B. express only one type of heavy chain and one type of light chain.
C. do not undergo alternative splicing until cell proliferation commences
D. do not secrete antibody until antigen is encountered
E. carry out affinity maturation directed at heavy chains and not light chains
F. derived from B-cell lymphomas are heterogeneous
B. express only one type of heavy chain and one type of light chain.
4-10 Which of the IgG subclasses is most efficient at activating complement? Explain why. Which is least efficient and why?
IgG3 is most efficient at complement activation. The hinge region of IgG3 is the longest of all the IgG subclasses. Its length and flexibility mak ethe IgG3 Fc region more accessible for binding C1 compared with the other IgG subclasses. IgG4 fails to activate complement because its Fc regions binds C1 poorly.
Which antibody is an opsonin?
IgG, IgA
Which antibody has complement activation?
IgA, IgG, IgM
Which antibody can be transported across the placenta?
IgG
Which antibody is most abundant in serum?
IgG
Which antibody is most abundant in mucosal secretions (like colostrum)?
IgA
Which antibody has sensitization of mast cells?
IgE, IgG
Which antibody has sensitization of basophils?
IgD, IgE
Which antibody has sensitization for killing by NK cells?
IgG
Which antibody is made in the body more than any other antibody?
IgA
Which antibody is least abundant in the serum?
IgE
4-12 Humanized monoclonal antibodies are best described as…
A. antibodies made in mice in which the mouse antibody genes have been replaced with human equivalents.
B. human antibodies in which the CDR loops have been replaced by mouse-derived CDRs of the desired specificity.
C. antibodies made in culture by human hybridomas
D. antibodies containing mouse Fab regions of both the heavy and light chain and human Fc regions.
E. antibodies containing human Fab regions of both the heavy and light chain and mouse Fc regions.
B. human antibodies in which the CDR loops have been replaced by mouse-derived CDRs of the desired specificity.
4-13 Which of the IgG subclasses would you think was in principle most desirable for use as a therapeutic monoclonal antibody, and why? Are there any disadvantages to using this subclass and how might they be overcome?
IgG4 would be considered the most desirable in principle because it lacks the ability to activate complement, and so will not trigger complement-mediated inflammation, which could cause damage to the patient. However, the monoclonal IgG4 will swap immunoglobulin chains with the patient’s IgG4 at high frequency, thus becoming functionally covalent, compromising its ability to bind as strongly to antigen as the other, stable, IgG subclasses. One solution would be to alter the CH3 region of IgG4 genetically in such a way that it cannot swap heavy:light chain units with other IgG4 antibodies but retains the inability to activate complement.
4-14 Which of the following statements best explains why the immune system can continue to make antibodies after treatment with the anti-CD20 antibody rituximab?
A. New CD20-positive B cells are reconstituted so quickly that antibody concentration during and after treatment is unaffected.
B. Rituximab stimulates B-cell proliferation, so for a short while after its administration there is actually an increase in antibody concentration.
C. Rituximab is a mouse monoclonal antibody and therefore its Fc region is unable to bind to the surface receptors on human NK cells that bind to Fc.
D. Plasma cells do not express CD20 on their cell surface, and antibody production by these cells continues unhampered.
E. Rituximab stimulates anti-antibody production, leading to its rapid clearance by the body.
D. Plasma cells do not express CD20 on their cell surface, and antibody production by these cells continues unhampered.
2. IgM and IgD are co-expressed on naive B cells by a process called: A. isotype switching B. somatic recombination C. somatic hypermutation D. alternative mRNA splicing E. affinity maturation
D. alternative mRNA splicing
3. Enhancement of receptor-mediated phagocytosis of immunoglobulin-coated antigen. A. monoclonal antibodies production B. isotype switching C. somatic hypermutation D. opsonization E. somatic recombination
D. opsonization
4. Since each B cell productively rearranges a single H and L chain allele, it exhibits? A. Affinity B. Allelic exclusion C. Antibody restriction D. Antigen binding diversity E. Cross reactivity
B. Allelic exclusion
- Antibody affinity for antigen depends on:
A. the antibody isotype
B. The complementary shape and charge of each antibody V region for its antigen epitope
C. the number of Fab regions in each antibody molecule
D. whether the antibody is in the serum or on the cell surface
E. whether the light chains are kappa or lambda
B. The complementary shape and charge of each antibody V region for its antigen epitope
