immunology High Yield - iren

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Immunology High Yield

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IMMUNOLOGY HIGH YIELD

Chapter 2: Elements of Innate and Acquired Immunity
Review Questions
For each question, choose the ONE BEST answer or completion.
1. Which of the following generally does not apply to bone marrow (a primary lymphoid organ)
and secondary lymphoid organs?
A. cellular proliferation
B. differentiation of lymphocytes
C. cellular interaction
D. antigen-dependent response
E. none of the above
2. Which of the following apply uniquely to secondary lymphoid organs?
A. presence of precursor B and T cells
B. circulation of lymphocytes
C. terminal differentiation
D. cellular proliferation
E. All of the above.
3. Which of the following does not apply to "innate" immune mechanisms?
A. absence of specificity
B. activation by a stimulus
C. involvement of multiple cell types
D. a memory component
4. Which of the following is the major function of the lymphoid system?
A. innate immunity
B. inflammation
C. phagocytosis
D. acquired immunity
E. None of the above.
5. Removal of the bursa of Fabricius from a chicken results in
A. a markedly decreased number of circulating T lymphocytes.
B. anemia.
C. delayed rejection of skin graft.
D. low serum levels of antibodies in serum.
E. All of the above.
F. None of the above.
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6. The germinal centers found in the cortical region of lymph nodes and the peripheral region of
splenic periarteriolar lymphatic tissue
A. support the development of immature B and T cells.
B. function in the removal of damaged erythrocytes from the circulation.
C. act as the major source of stem cells and thus help to maintain hematopoiesis.
D. provide an infrastructure that on antigenic stimulation contains large populations of B
lymphocytes and plasma cells.
E. are the sites of NK-cell differentiation.
7. Which of the following is correct?
A. NK cells proliferate in response to antigen.
B. NK cells kill their target cells by phagocytosis and intracellular digestion.
C. NK cells are a subset of polymorphonuclear cells.
D. NK-cell killing is extracellular.
E. NK cells are particularly effective against certain bacteria.


Chapter 2: Elements of Innate and Acquired Immunity
Answers to Review Questions
1. D Cellular proliferation, differentiation of lymphocyte, and cellular interactions can take
place in bone marrow (or bursa of Fabricius). However, antigen-dependent responses occur in
the secondary lymphoid organs, such as the spleen and lymph nodes.
2. C Terminal differentiation of B cells into plasma cells occurs only in secondary lymphoid
organs, such as the spleen and lymph nodes. Circulation of lymphocytes and cellular
proliferation (but not antigen-dependent responses of terminal differentiation) also take place in
the primary lymphoid organs, such as the bursa of Fabricius, or its equivalent, and the thymus.
The bone marrow is the site where pluripotential stem cells differentiate into precursor B and T
cells.
3. D Innate immunity has none of the antigenic specificity exhibited by acquired immunity. It
is activated by such stimuli as the invasion of the foreign particles into the body. Innate
immunity involves multiple cell types, such as those of the monocytic series (macrophages) and
those of the granulocytic series (neutrophils, eosinophils, etc.).
4. D The major function of the lymphoid system is the recognition of foreign antigen by
lymphocytes, which leads to the acquired immune response. Functions such as phagocytosis and
inflammation do not necessarily require the lymphoid system, and they constitute part of innate
immunity.
5. D Removal of the bursa of Fabricius from a chicken results in low levels of antibodies in
serum, since this organ serves as a primary lymphoid organ in which B lymphocytes (which
eventually synthesize and secrete antibodies) undergo maturation. The removal of the organ will
not result in a marked decrease in the number of circulating T lymphocytes, nor will it result in
anemia, characterized by a marked decrease in erythrocyte count, since erythrocytes undergo
maturation outside the bursa. Bursectomy has no effect on rejection of skin grafts.
6. D On antigenic stimulation, the germinal centers contain large populations of B
lymphocytes undergoing mitosis and plasma cells secreting antibodies. Virgin
immunocompetent lymphocytes are developed in the primary lymphoid organs, not in the
secondary lymphoid organs, such as the spleen and lymph nodes. Germinal centers do not
participate in the removal of damaged erythrocytes, nor are they a source of stem cells; the latter
are found in the bone marrow.
7. D NK cells are large granular lymphocytes. Their number does not increase in response to
antigen. Their killing is extracellular, and their target cells are virus-infected cells or tumor cells.
They are not particularly effective against bacterial cells.














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Chapter 3: Immunogens and Antigens
Review Questions
For each question, choose the ONE BEST answer or completion.
1. The following properties render a substance immunogenic:
A. high molecular weight.
B. chemical complexity.
C. sufficient stability and persistence after injection.
D. All of the above.
E. All of the above are essential but not sufficient.
2. The protection against small pox afforded by prior infection with cowpox represents
A. antigenic specificity.
B. antigenic cross-reactivity.
C. enhanced viral uptake by macrophages.
D. innate immunity.
E. passive protection.
3. Converting a toxin to a toxoid
A. makes the toxin more immunogenic.
B. reduces the pharmacologic activity of the toxin.
C. enhances binding with antitoxin.
D. induces only innate immunity.
E. increases phagocytosis.
4. Haptens
A. require, carrier molecules to be immunogenic.
B. react with specific antibodies when homologous carriers are not employed.
C. interact with specific antibody even if the hapten is monovalent.
D. cannot stimulate secondary antibody responses without carriers.
E. All of the above.
5. An immunologic adjuvant is a substance that
A. reduces the toxicity of the immunogen.
B. enhances the immunogenicity of haptens.
C. enhances hematopoiesis.
D. enhances the immune response against the immunogen.
E. enhances immunologic cross-reactivity.
6. An antibody made against the antigen tetanus toxoid (TT) reacts with it even when the TT is
denatured by disrupting all disulfide bonds. Another antibody against TT fails to react when the
TT is similarly denatured. The most likely explanation can be stated as follows:
A. The first antibody is specific for several epitopes expressed by TT.
B. The first antibody is specific for the primary amino acid sequence of TT, whereas the
second is specific for conformational determinants.
C. The second antibody is specific for disulfide bonds.
D. The first antibody has a higher affinity for TT.


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Chapter 3: Immunogens and Antigens
Answers to Review Questions
1. E All of the properties are essential but not sufficient, since, for immunogenicity, the
substance must be foreign to the immunized individual.
2. B The protection against smallpox provided by prior infection with cowpox is an example
of antigenic cross-reactivity. Immunization with cowpox leads to the production of antibodies
capable of reacting with smallpox because the two viruses share several identical, or structurally
similar, determinants.
3. B Conversion of a toxin to a toxoid is performed in order to reduce the pharmacologic
activity of the toxin, so that sufficient toxoid can be injected to induce an immune response.
4. E Haptens are substances, usually of low molecular weight and univalent, that, by
themselves, cannot induce immune responses (primary or secondary), but can do so if conjugated
to high-molecular-weight carriers. The haptens can and do interact with the induced antibodies,
without it being necessary that they be conjugated to the carrier.
5. D An immunologic adjuvant is a substance that, when mixed with an immunogen, enhances
the immune response against that immunogen. It does not enhance cross-reactivity, nor does it
enhance hematopoiesis. An adjuvant does not enhance the immune response against a hapten,
which requires its conjugation to an immunogenic carrier to induce a response against the
hapten. The adjuvant has no relevance to possible toxicity of an immunogen.
6. B Antibodies can recognize single epitopes formed by primary sequence structures or
secondary, tertiary, and quaternary conformational structures. Denaturing a protein by disrupting
disulfide bonds generally destroys conformational determinants. Therefore it is likely that the
first antibody reacts with a primary amino acid sequence determinant that is present on both
native and denatured TT, while the second antibody sees a conformational determinant only on
native TT.

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Chapter 4: Antibody Structure and Function
Review Questions
For each question, choose the ONE BEST answer or completion.
1. The class-specific antigenic determinants (epitopes) of immunoglobulins are associated with
A. L chains.
B. J chains.
C. disulfide bonds.
D. H chains.
E. variable regions.
2. The idiotype of an antibody molecule is determined by the amino acid sequence of the
A. constant region of the L chain.
B. variable region of the L chain.
C. constant region of the H chain.
D. constant regions of the H and L chains.
E. variable regions of the H and L chains.
3. Injection into rabbits of a preparation of pooled human IgG could stimulate production of
A. anti-heavy-chain antibody.
B. anti-chain antibody.
C. anti-chain antibody.
D. anti-Fc antibody.
E. All are correct.
4. A polyclonal antiserum raised against pooled human IgA will react with
A. human IgM.
B. light chains.
C. human IgG.
D. J chain.
E. All are correct.
5. An individual was found to be heterologous for IgG1 allotypes 3 and 12. The different possible
IgG1 antibodies produced by this individual will never have
A. two H chains of allotype 12.
B. two L chains of either or .
C. two H chains of allotype 3.
D. two H chains, one of allotype 3 and one of allotype 12.

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6. Papain digestion of an IgG preparation of antibody specific for the antigen hen egg albumin
(HEA) will
A. lose its antigen specificity.
B. precipitate with HEA.
C. lose all interchain disulfide bonds.
D. produce two Fab molecules and one Fc fragment.
E. None of the above.
7. The first immunoglobulin synthesized by the fetus is
A. IgA.
B. IgE.
C. IgG.
D. IgM.
E. None; the fetus does not synthesize immunoglobulins.
8. The following properties of human IgG are true except:
A. It can pass through the placenta.
B. It can be cleaved by pepsin and yet remain divalent.
C. Its half-life is approximately 23 days.
D. It induces the formation of leukocytes.
E. It participates in the activation of complement.
F. It has the longest half-life of all Ig isotopes.
9. The relative level of specific IgM antibodies can be of diagnostic significance because
A. IgM is easier to detect than the other isotypes.
B. viral infection often results in very high IgM responses.
C. IgM antibodies are more often protective against reinfections than are the other isotopes.
D. relatively high levels of IgM often correlate with a first recent exposure to the inducing
agent.
10. The primary and secondary antibody responses differ in
A. the predominant isotype generated.
B. the number of lymphocytes responding to antigen.
C. the speed at which antibodies appear in the serum.
D. the biologic functions manifested by the Ig isotypes produced.
E. All of the above.






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Chapter 4: Antibody Structure and Function
Answers to Review Questions
1. D The five classes of Ig molecules are defined by the H chains (, , , , .
2. E The idiotype is the antigenic determinant of an Ig molecule, which involves its antigen-combining
site, which in turn consists of contributions from the variable regions of both L and H
chains.
3. E All are correct statements. Since a pool of IgG is injected, it can be assumed that both 
and chains will be present and that antibodies will be made against them, as well as against the
other determinants (H chain and Fc region) present in all IgG molecules.
4. E All are correct statements. Antibody to IgA will have antibody specific for and light
chains, which, of course, will react with IgG and IgM, both of which have andchains.
Antibody will also be present against J chain if the IgA used for immunization was dimeric.
5. D In any immunoglobulin produced by a single cell, the two H chains and the two L chains
are identical. Therefore, any antibody molecule in this individual would have either allotype 3 H
chains or allotype 12 H chains, not a mixture. Similarly, the antibody would have either two or
two chains.
6. D Papain digestion cleaves the IgG molecules above the hinge region, generating two Fab
molecules and an Fc fragment. the Fab fragments can still bind to HEA, but since they are not
held together by disulfide binds, they cannot precipitate the antigen. This contrasts with the
effects of pepsin treatment of IgG, which cleaves below the hinge region, leaving intact one
divalent (F(ab2 molecule capable of precipitating the antigen. Fragments of pepsin-treated
HEA-specific antibody will have the same affinity for the antigen as the original Fab regions of
the antibody, since the CDR regions of the molecules are preserved.
7. D The first (and only) immunoglobulin synthesized by the fetus is IgM. The IgG present in
the fetus is maternal IgG that has passed through the placenta. No other immunoglobulins are
found in the fetus.
8. D Human IgG is the only Ig that passes across the placenta. It has a half-life of 23 days, the
longest of all Ig isotypes. It can be cleaved by pepsin to yield a divalent antibody portion
F(ab2, and it participates in the activation of complement. It does not induce the formation of
leukocytes. Thus all the statements are true except D.
9. D Only the last statement is correct. Relatively high levels of IgM often correlate with first
recent exposure to an inducing agent, since IgM is the first isotype synthesized in response to an
immunogen. All other statements are not true.
10. E All are correct. The statements are self-explanatory.


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Chapter 5: Antigen-Antibody Interactions, Immune Assays, and Experimental Systems
Review Questions
For each question, choose the ONE BEST answer or completion.
1. Primary interactions between antigens and antibodies involve all of the following except
A. covalent bonds.
B. van der Waals forces.
C. hydrophobic forces.
D. electrostatic forces.
E. a very close fit between an epitope and the antibody.
2. If an IgG antibody preparation specific for hen egg lysosome (HEL) is treated with papain to
generate Fab fragments, which of the following statements concerning the avidity of such
fragments is true?
A. They will have a longer avidity for HEL as compared with the intact IgG.
B. They will have a higher avidity for HEL as compared with the intact IgG.
C. There will have the same avidity for HEL as the intact IgG.
D. They will have lost their avidity to bind to HEL.
E. They will have the same avidity, but will have a lower affinity for HEL.
3. Western assays used to test serum samples for the presence of antibodies to infectious agents,
such as HIV, are particularly useful as diagnostic assays because
A. they are more sensitive than ELISA.
B. antibodies specific for multiple antigenic epitopes can be detected.
C. they provide quantitative data for sample analysis.
D. they allow multiple samples to be tested simultaneously.
E. they are less expensive and take less time to perform as compared with ELISA.
4. The major difference between transgenic mice and knockout mice is that
A. transgenic mice always employ the use of cloned genes derived from other species.
B. transgenic mice have foreign genes that integrate at targeted loci through homologous
recombination.
C. transgenic mice have a functional foreign gene added to their genome.
D. knockout mice always have a unique phenotype.
5. SCID mice have a genetic defect that prevents development of functional
A. hematopoietic cells.
B. B cells and T cells.
C. T cells and NK cells.
D. pluripotential stem cells.
E. myeloid cells.

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6. Which of the following statements regarding B cell hybridomas is false?
A. They are immortal cell lines that produce antibodies of a single specificity.
B. They are derived from B cells that are first cloned and grown in cell culture for short
periods.
C. They contain a large nucleus formed by the fusion of two nuclei.
D. They can be used to manufacture diagnostic or therapeutic monoclonal antibodies.
E. They are derived by fusing B cells with malignant plasma cells that are unable to secrete
immunoglobulin.
7. An ELISA designed to test for the presence of serum antibody for a new strain of pathogenic
bacteria is under development. Initially, a monoclonal antibody specific for a single epitope of
the organism was used both to sensitize the wells of the ELISA plate and as the enzyme-labeled
detecting antibody in a conventional sandwich ELISA. The ELISA failed to detect the antigen
despite the use of a wide range of antibody concentrations. What is the most probably cause of
this problem?
A. The antigen is too large.
B. The antibody has a low affinity for the antigen.
C. The monoclonal antibody used to sensitize the wells is blocking access of the epitope,
thus when the same antibody is enzyme-labeled, it cannot bind to the antigen.
D. The enzyme-labeled antibody used should have been a different isotype than the
sensitizing antibody.
E. The monoclonal antibody used is probably unstable.


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Chapter 5: Antigen-Antibody Interactions, Immune Assays, and Experimental Systems
Answers to Review Questions
1. A No covalent bonds are involved in the interaction between antibody and antigen. The
binding forces are relatively weak and include van der Waal's forces, hydrophobic forces, and
electrostatic forces. A very close fit between an epitope and the antibody is required.
2. A Avidity denotes the overall binding energy between antigens and multivalent antigens.
Since the valency of the Fab fragments is one as compared with the HEL-specific IgG molecule,
which has a valence of 2 (due to the presence of two Fab regions), the avidity of the fragments
will be lower. Choice E is incorrect since the affinity of the Fab fragments will be the same as
each of the Fab regions of the intact IgG molecule.
3. B In Western assays, electrophoretic separation techniques are used to resolve the
molecular mass of a given antigen or mixtures of antigens. Since antibody responses to
infectious agents generate polyclonal responses by virtue of the complex antigenic determinants
expressed by such agents, Western assays can confirm the presence of these antibodies, which
react with the electrophoretically separated antigens of known molecular weights.
4. C Cloned foreign genes from either the same or other species are introduced into mice to
generate a transgenic strain. Integration is random and occurs in both somatic and germ line
cells. Choice D is incorrect because sometimes knockout mice do not have a phenotype unique
caused by the replacement of a functional gene with one that is nonfunctional, probably due to
the activity of redundant or compensatory mechanisms.
5. B SCID mice possess an autosomal recessive mutation that causes a disorder in which B
and T cells fail to develop. Like their human counterparts, SCID mice are compromised with
respect to lymphoid defense mechanisms. Pluripotential stem cells present in SCID mice can
give rise to other hematopoietic lineages, including cells in the myeloid lineage and NK cells.
6. B The method used to general B cell hybridomas employs the fusion of B cells (e.g., from
the spleen and lymph nodes) harvested from immunized mice with a selected population of
malignant plasma cells unable to secrete immunoglobulin. Antigen-specific B cells are not
cloned first and then fused with such plasma cells.
7. C In a sandwich ELISA, an antibody (often monoclonal) is used to coat ELISA wells
followed by blocking with a nonspecific protein to saturate any unbound sites. The antigen is
then added, followed by the addition of a second antigen-specific antibody that is enzyme-labeled.
A polyclonal, antigen-specific antibody is often used as the enzyme-labeled reagent.
This is done because the epitope detected by the coating antibody (a monoclonal antibody in this
case) may be blocked by that antibody, thus preventing its access if the same monoclonal were
used as the enzyme-labeled detecting antibody.

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Chapter 6: The Genetic Basis of Antibody Structure
Review Questions
For each question, choose the ONE BEST answer or completion.
1. The DNA for an H chain in a B cell making IgG2 antibody for diphtheria toxoid has the
following structure: 5-V17D5J2 C2C4CC23. How many individual
rearrangements were required to go from the embryonic DNA to this B-cell DNA?
A. 1
B. 2
C. 3
D. 4
E. none
2. If you had 50 V, 20 D, and 6 J regions able to code for a heavy chain, and 40 V and 5 J region
genes able to code for a light chain, you could have a maximum repertoire of
A. 76 + 45 = 121 antibody specificities.
B. 76 X 45 = 3,420 specificities.
C. (470 X 5) + (50 X 20 X 6) = 6,200 specificities.
D. (40 X 5) X (50 X 20 X 6) = 1,200,000 specificities.
E. more than 1,200,000 specificities.
3. The antigen specificity of a particular B cell
A. is induced by interaction with antigen.
B. is determined only by the L-chain sequence.
C. is determined by H + L-chain variable region sequences.
D. changes after isotype switching.
E. is determined by the heavy-chain constant region.
4. If you could analyze, at the molecular level, a plasma cell making IgA antibody, you would find
all of the following except
A. a DNA sequence for V, D, and J genes translocated near the CDNA exon.
B. mRNA specific for either or light chains.
C. mRNA specific for J chains.
D. mRNA specific for chains.
E. a DNA sequence coding for the T-cell receptor for antigen.


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5. The ability of a single B cell to express both IgM and IgD molecules on its surface at the same
time is made possible by
A. allelic exclusion.
B. isotype switching.
C. simultaneous recognition of two distinct antigens.
D. selective RNA splicing.
E. use of genes from both parental chromosomes.
6. Which of the following statements concerning the organization of immunoglobulin genes is
correct?
A. V and J regions of embryonic DNA have already undergone a rearrangement.
B. Light-chain genes undergo further rearrangement after surface IgM is expressed.
C. VH gene segments can rearrange with Jor Jgene segments.
D. The VDJ segments coding for an immunoglobulin VH region m ay associate with
different heavy-chain constant region genes.
E. After VDJ joining has occurred, a further rearrangement is required to bring the VDJ unit
next to the Cgene.
7. Which of the following does not contribute to the generation of diversity of B-cell antigen
receptors?
A. multiple V genes in the germ line
B. random assortment of L and H chains
C. imprecise recombination of V and J or V, D, and J segments
D. inheritance of multiple C-region genes
E. somatic hypermutation
8. Which of the following concerning Ig expression on a B cell is incorrect:
A. The light chains of the IgM and IgD have identical amino acid sequences.
B. The constant parts of the heavy chains of the IgM and IgD have different amino acid
sequences.
C. The IgM and IgD have different antigenic specificities.
D. If the B cell is triggered by antigen and T-cell signals to proliferate and differentiate into
antibody secreting plasma cells, the cell can potentially secrete IgG, IgE, or IgA
antibody.
E. The IgM on the surface will have either light chains or light chains, but not both.


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9. Which of the following plays a role in changing the antigen binding site of a B cell after
antigenic stimulation?
A. junctional diversity
B. combinatorial diversity
C. germ-line diversity
D. somatic hypermutation
E. differential splicing of primary RNA transcripts
__________________________________________________ __________________________
Case Study
As a member of a research team studying a tribe found in a remote region of New Guinea, you make the
astonishing discovery that they have only two V genes for the L chain and three V genes for the H chain
of immunoglobulins. Nevertheless, they seem healthy and able to resist the diversity of pathogenic
organisms endemic to the area. Suggest how this might be accomplished.


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Chapter 6: The Genetic Basis of Antibody Structure
Answers to Review Questions
1. C Three DNA rearrangements are required. First, D5 J2 rearrangement occurs, followed
by V17 D5J2. This permits synthesis of IgM and IgD molecules using V17D5J2. The third
rearrangement is the class switch of V17D5J2CCto V17D5J2C2, leading to the synthesis of
IgG2 molecules.
2. E While 1,200,000 would be the product of all possible combinations of genes, the
generation of many more antibody specificities is likely as a result of imprecise recombinations
of VJ or VDJ segments, insertional diversity, and somatic hypermutation.
3. C The antigenic specificity is determined by the sequences and hence the structure formed
by the combination of heavy- and light-chain variable regions.
4. D As a consequence of the rearrangement of the VDJ to C in the IgA producing cell the
C gene will have been deleted. The other DNA sequences and mRNA species will be found in
the cell.
5. D The simultaneous synthesis of IgM and IgD is made possible by the alternate splicing of
the primary RNA transcript 5VDJCC3; to give either VDJCor VDJCmessages.
6. D This is the basis of isotype or class switching.
7. D The presence of multiple CH region genes, although the basis for functional diversity,
does not contribute to the diversity of antigen-specific receptors.
8. C The IgM and IgD expressed on a single B cell use the same heavy- and light-chain V(D)J
gene units and, therefore, have the same antigenic specificity.
9. D Of the mechanisms described for generating diversity of Ig molecules, only somatic
hypermutation affects the antigen binding site after antigen stimulation.
__________________________________________________ __________________________
Answer to Case Study
Despite the paucity of V-region genes, these individuals presumably retain other mechanisms for
generating diversity. These include the presence of multiple J and D gene segments in the germ line,
junctional diversity due to deletion or insertion of bases at joining sites, random assortment of H and L
chains, and somatic hypermutation. It is, therefore, conceivable that, even with their limited V-gene
repertoire, they can generate sufficient diversity of antibody specificity to survive.

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Chapter 7: Biology of the B Lymphocyte
Review Questions
For each question, choose the ONE BEST answer or completion.
1. The earliest stages of B-cell differentiation
A. occur in the embryonic thymus.
B. require the presence of antigen.
C. involve rearrangement of -chain gene segments.
D. involve rearrangement of surrogate light-chain gene segments.
E. involve rearrangement of heavy-chain gene segments.
2. Which of the following is expressed on the surface of the mature B lymphocyte?
A. CD40
B. MHC class II molecules
C. CD32
D. IgM and IgD
E. All of the above.
3. Which of the following statements is incorrect?
A. Antibodies in a secondary immune response generally have a higher affinity for antigen
than antibodies formed in a primary response.
B. Somatic hypermutation of V region genes may contribute to changes in antibody affinity
observed during secondary responses.
C. Synthesis of antibody in a secondary response occurs predominantly in the blood.
D. Isotype switching occurs in the presence of antigen.
E. Predominantly IgM antibody is produced in the primary response.
4. Immature B lymphocytes
A. produce only chains.
B. are progenitors of T as well as B lymphocytes.
C. express both IgM and IgD on their surface.
D. are at a stage of development where contact with antigen may lead to unresponsiveness.
E. must go through the thymus to mature.
5. Antigen binding to the B-cell receptor
A. transduces a signal through the antigen-binding chains.
B. invariably leads to B-cell activation.
C. transduces a signal through the Igand Igmolecules.
D. results in macrophage activation.
E. leads to cytokine synthesis, which activates T cells.

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6. Which of the following would not be found on a memory B cell:
A. Igand Ig
B. heavy chains
C. heavy chains
D. surrogate light chains
E. light chains

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Chapter 7: Biology of the B Lymphocyte
Answers to Review Questions
1. E The earliest events in B-cell differentiation take place in fetal liver and bone marrow in
the adult and involve rearrangement of heavy-chain V, D, and J gene segments.
2. E All the molecules are expressed on the surface of the mature B cell.
3. C Antibody synthesis in secondary responses occurs predominantly in lymph nodes, not
blood.
4. D In immature B cells, which express only IgM, contact with antigen leads to
unresponsiveness rather than activation.
5. C The molecules Igand Ig, which are associated with the surface Ig molecule, transduce
a signal following antigen binding to surface Ig.
6. D Surrogate light chains are expressed only at the pre-B cell stage of B-cell differentiation.


Chapter 8: The Role of the Major Histocompatibility Complex in the Immune Response
Review Questions
For each question, choose the ONE BEST answer or completion.
1. All the following are characteristics of both MHC class I and class II molecules except:
A. They are expressed codominantly.
B. They are expressed constitutively on all nucleated cells.
C. They are glycosylated polypeptides with domain structure.
D. They are involved in presentation of antigen fragments to T cells.
E. They are expressed on the surface membrane of B cells.
2. MHC class I molecules are important for which of the following?
A. binding to CDS molecules on T cells
B. presenting exogenous antigen (e.g., bacterial protein) to B cells
C. presenting viral protein to antigen-presenting cells such as macrophages
D. binding to CD4 molecules on T cells
E. binding to Ig on B cells
3. Which of the following is incorrect concerning MHC class II molecules?
A. B cells may express different MHC class II molecules on their surface.
B. MHC class II molecules are synthesized in the endoplasmic reticulum of many cell types.
C. Genetically different individuals express different MHC class II alleles.
D. MHC class II molecules are associated with 2-microglobulin on the cell surface.
E. A peptide that does not bind to an MHC class II molecule will not trigger a CD4 + T cell
response.
4. Products of TAP-1 and -2 genes
A. bind 2-microglobulin.
B. prevent peptide binding to MHC molecules.
C. are part of the proteasome.
D. transport peptides into the endoplasmic reticulum for binding to MHC class I.
E. transport peptides into the endoplasmic reticulum for binding to MHC class II.


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5. Which of the following is incorrect concerning the processing of an antigen, such as a bacterial
protein, in the acid compartments of the cell?
A. It results in production of potentially immunogenic peptides that associate with MHC
class II molecules.
B. Predominantly exogenous antigens are processed by this pathway.
C. It may lead to activation of CD4 + T cells.
D. It may lead to the activation of CD8 + T cells.
E. Bacterially derived peptides displace a fragment of the invariant chain from the MHC
class II binding groove.
6. Which of the following statements about the MHC is incorrect?
A. It codes for complement components.
B. It codes for both chains of the MHC class I molecule.
C. It codes for both chains of the MHC class II molecule.
D. It is associated with susceptibility and resistance to different diseases.
E. The total set of MHC alleles on the chromosome is known as the MHC haplotype.


22
Chapter 8: The Role of the Major Histocompatibility Complex in the Immune Response
Answers to Review Questions
1. B MHC class I molecules are expressed on nearly all nucleated cells, but the constitutive
expression of MHC class II molecules is more limited (B cells, dendritic cells, and thymic
epithelial cells). MHC class II expression can be induced on other cell types (such as
macrophages, endothelial cells, and human T cells) by cytokines.
2. A As described further in Chapters 9 and 10, the interaction of CD8 on the T cell and an
invariant region of MHC class I molecule is crucial in the triggering of CD8 + T cells.
3. D The MHC class I molecule, not the MHC class II molecule, associates with 2-
microglobulin.
4. D The products of the TAP-1 and -2 genes selectively transport peptides 8-9 amino acids in
length from the cytoplasm into the ER where they bind to MHC class I molecules.
5. D CD8 + T cells are generally not activated by processing in acid compartments; exogenous
antigen processing in acid compartments results in the generation of peptides, some of which can
displace the CLIP fragment of the invariant chain from the MHC class II binding groove. The
peptide-MHC class II complexes move to the cell surface and can interact with a CD4 + T cell
with the appropriate receptor.
6. B The 2-microglobulin gene is located outside the MHC, on a different chromosome.



23
Chapter 9: Biology of the T Lymphocyte
Review Questions
For each question, choose the ONE BEST answer or completion.
1. Which of the following statements concerning T-cell development is correct?
A. Progenitor T cells that enter the thymus from the bone marrow have already rearranged
their T cell receptor genes.
B. Interaction with thymic non-lymphoid cells is critical.
C. Maturation in the thymus requires the presence of foreign antigen.
D. MHC class II molecules are not involved in positive selection.
E. Mature, fully differentiated T cells are found in the cortex of the thymus.
2. The development of self-tolerance in the T-cell compartment is important for the prevention of
autoimmunity. Which of the following results in T-cell self-tolerance?
A. allelic exclusion
B. somatic hypermutation
C. thymocyte proliferation
D. positive selection
E. negative selection
3. Which of the following statements is correct?
A. The TCR chains transduce a signal into a T cell.
B. A cell depleted of its CD4 molecule would be unable to recognize antigen.
C. T cells with fully rearranged chains are not found in the thymus.
D. T cells expressing the receptor are found only in the thymus.
E. Immature CD4 + CD8 + T cells form the majority of T cells in the thymus.
4. Which of the following is incorrect regarding mature T cells that use as their antigen-specific
receptor?
A. They co-express CD3 on the cell surface.
B. They may be either CD4 + or CD8 + .
C. They interact with peptides derived from nonself antigens.
D. They can further rearrange their TCR genes to express as their receptor.
E. They circulate through blood and lymph and migrate to secondary lymphoid organs.

24
5. CD4
A. binds directly to peptide antigen.
B. binds to an invariant portion of MHC class I molecules.
C. binds to an invariant portion of MHC class II molecules.
D. binds to CD8 on the T cell surface.
E. binds to the peptide-binding site of MHC class II.
6. Which of the following statements is incorrect concerning TCR and Ig genes?
A. In both B- and T-cell precursors, multiple V-, D-, J-, and C-region genes exist in an
unrearranged configuration.
B. Rearrangement of both TCR and Ig genes involves specific recombinase enzymes that
bind to specific regions of the genome.
C. Both Ig and TCR are able to switch C-region usage.
D. Both Ig and TCR exhibit allelic exclusion.
E. Both Ig and the TCR use combinatorial association of V, D, and J genes and junctional
imprecision to generate diversity.
7. Which of the following statements is incorrect concerning antigen-specific receptors on both B
and T cells?
A. They are clonally distributed transmembrane molecules.
B. They have extensive cytoplasmic domains that interact with intracellular molecules.
C. They consist of polypeptides with variable and constant regions.
D. They are associated with signal transduction molecules at the cell surface.
E. They can interact with peptides derived from nonself antigens.

25
Chapter 9: Biology of the T Lymphocyte
Answers to Review Questions
1. B Interaction of thymocytes with thymic stromal cellscortical epithelial cells and inter-digitating
dendritic cells at the corticomedullary junctionis critical in T cell development.
2. E Negative selection removes developing T cells with potential reactivity to self-molecules.
3. E CD4 + CD8 + T cells form the majority of cells in the thymus.
4. D The genes of T cells that use as their receptor cannot further rearrange to use as
their receptor; TCR gene segments are interspersed with the locus and are deleted when the
locus rearranges.
5. C CD4 expressed on T cells binds to an invariant or nonpolymorphic region of all MHC
class II molecules.
6. C The ability to change the heavy-chain constant region while retaining the same antigen
specificity is a property unique to Ig. The other features are common to both the TCR and Ig.
7. B Both the TCR and Ig have short cytoplasmic tails. The signal transduction molecules
associated with the antigen-binding chains interact with intracellular molecules


26
Chapter 10: Activation and Function of T and B Cells
Review Questions
For each question, choose the ONE BEST answer or completion.
1. The role of the antigen-presenting cell in the immune response is all of the following except
A. the limited catabolism of polypeptide antigens.
B. to allow selective association of MHC gene products and peptides.
C. to supply second signals required to fully activate T cells.
D. to present non-self peptides associated with MHC class II molecules to B cells.
E. to present peptide-MHC complexes to T cells with the appropriate receptor.
2. Which of the following statements about interleukin 2 (IL-2) is incorrect?
A. It is produced primarily by activated macrophages.
B. It is produced by CD4 + T cells.
C. It can induce the proliferation of CD4 + T cells.
D. It binds to a specific receptor on CD4 + T cells.
E. It can activate CD8 + T cells in the presence of antigen.
3. CD40 Ligand (CD154) is expressed by which of the following?
A. B cells
B. dendritic cells
C. resting T cells
D. activated T cells
E. all leukocytes
4. Which of the following statements about the activation of CD4 + cells in incorrect?
A. Binding of peptide + MHC to the TCR results in rapid phosphorylation of tyrosine
residues in proteins associated with the TCR.
B. Intracellular calcium levels rise rapidly following activation.
C. Only peptide bound in the groove of MHC class II activates the CD4 + T cell.
D. Interaction of B7 and CD28 stabilizes IL-2 mRNA so effective IL-2 translation occurs.
E. The activated cell synthesizes IL-2 and a receptor for IL-2.
5. Which of the following statements about cytokines synthesized by CD4 + TH1 and TH2 subsets is
incorrect?
A. Cytokines produced by TH1 cells include IFN-and TNF-.
B. Cytokines produced by TH2 cells are important in allergic responses.
C. TH1 cells secrete cytokines that induce macrophage and NK cell activation.
D. TH2 cells secrete cytokines that activate CD8 + T cells.
E. TH2 cell cytokines may inhibit the action of TH1 cells.


27
6. Which of the following statements about CD8 + CTL is incorrect?
A. They lyse targets by synthesizing perforin and granzymes.
B. They cause target cell apoptosis.
C. They cannot kill CD4 + T cells.
D. They interact with their target through paired cell surface molecules.
E. They must be activated before exerting their cytotoxic function.
7. Infection with vaccinia virus results in the priming of virus-specific CD8 + T cells. If these
vaccinia virus-specific CD8 + T cells are subsequently removed from the individual, which of the
following cells will they kill in vitro?
A. vaccinia-infected cells expressing MHC class II molecules from any individual
B. influenza-infected cells expressing the same MHC class I molecules as the individual
C. uninfected cells expressing the same MHC class I molecules as the individual
D. vaccinia-infected cells expressing the same MHC class I molecules as the individual
E. vaccinia-infected cells expressing the same MHC class II molecules as the individual
8. Bacterial lipopolysaccharide (LPS), a T-independent antigen, stimulates antibody production in
mice. Which of the following is incorrect?
A. The antibody produced will be predominantly IgM.
B. Memory B cells will not be induced.
C. IL-4 and IL-5 are required for the production of antibody during the response.
D. The polymeric nature of the antigen crosslinks B-cell surface receptors.
E. B cell activation involves phosphorylation of intracellular molecules.
__________________________________________________ __________________________
Case Study
Great effort is now being directed at developing vaccines for a variety of diseases. In one study, it was
found that antibody to a particular epitope on a protein of the pathogens surface membrane was
protective. The structure of this epitope was determined to be a peptide 10 amino acids in length. This
peptide was synthesized and used to immunize individuals exposed to the pathogen. Disappointingly,
no protection was seen. Can you suggest any reasons for this failure?

[ArchivalUser]

28
Chapter 10: Activation and Function of T and B Cells
Answers to Review Questions
1. D The antigen-presenting cell does not present peptide + MHC class II to B cells. The other
statements are all features of the antigen-presenting cell.
2. A IL-2 is produced almost exclusively by activated T cells.
3. D CD40 ligand (CD154) is expressed on the surface of the CD4 + T cell as a consequence of
the activation that follows the binding of peptide + MHC class II to the TCR.
4. C Agents other than peptides bound to MHC class II can activate CD4 + T cells; these
include superantigens, antigens presented by CD1, and polyclonal inactivators.
5. D TH1 rather than TH2 cells secrete cytokines that activate CD8 + T cells.
6. C A CDS + CTL can kill any cell expressing an MHC class I molecule in association with a
non-self peptide, including, for example, a CD4 + T cell infected with HIV.
7. D The principle of MHC restriction indicates that the TCR of CD8 + T cells interacts with
target cells that express specific peptide bound to self-MHC class I molecules. Thus, vaccinia-primed
CD8 + T cells recognize and hence kill only vaccinia-infected targets that express self
MHC class I.
8. C T-independent antigens, because they do not generate T cell-derived cytokines, do not
produce IL-4 or IL-5. Thus, no isotype switching or memory cell induction occurs in response to
T-independent antigens.
__________________________________________________ __________________________
Answer to Case Study
Several possibilities may be considered, such as size and complexity of the peptide, which are required
for immunogenicity. The more likely failure, however, was that the response to the pathogens
membrane protein was almost certainly a thymus-dependent response. Therefore, immunization with
the epitope seen by the B cells would not work unless epitopes seen by helper T cells were also present.
Attempts at producing synthetic vaccines are now directed toward incorporating the B cell-specific
epitopes in carriers containing adequate helper T epitopes that will induce both help and
memory responses. This would provide a better possibility for protection following exposure to the
pathogen.


29
Chapter 11: Control Mechanisms in the Immune Response
Review Questions
For each question, choose the ONE BEST answer or completion.
1. An individual does not make an immune response to a self-protein because
A. self-proteins cannot be processed into peptides.
B. peptides from self-proteins cannot bind to MHC class I.
C. peptides from self-proteins cannot bind to MHC class II.
D. lymphocytes that express a receptor reactive to a self-protein are inactivated by deletion
or anergy.
E. developing lymphocytes cannot rearrange V genes required to produce a receptor for self-proteins.
2. Which of the following statements is incorrect.
A. Interaction of Fas and FasL can lead to apoptosis.
B. Both Fas and Fas L can be expressed on activated T cells.
C. Both Fas and Fas L can be expressed on B cells.
D. Cells in immunologically privileged sites can express FasL.
E. FasFasL-mediated apoptosis prevents uncontrolled T-cell clone growth.
3. Which of the following is incorrect concerning immune tolerance?
A. Tolerance induction is antigen-specific.
B. Tolerance results from inactivation and/or elimination of B and/or T cells.
C. Tolerance can be induced in both young and old individuals.
D. Immature neutrophils are more susceptible to tolerance than mature neutrophils.
E. The breakdown of tolerance can result in autoimmunity.
4. Which of the following statements is incorrect concerning the immune response to antigens?
A. Reactivity is influenced by extremes of age.
B. Greater immune responses are produced when antigen is given with adjuvant.
C. Impaired nutrition depresses immunity.
D. The presence of pre-existing antibody does not affect the subsequent response to antigen.
E. Different protein antigens stimulate different levels of antibody production.
5. All of the following procedures would be likely to induce tolerance to a protein antigen except
A. intramuscular injection of the antigen in adjuvant.
B. intravenous injection of deaggregated protein.
C. injection of cyclosporine with the antigen.
D. injection of antigen at a stage in development before mature lymphocytes appear.
E. intravenous injection of small amounts of antigen.


30
6. When a tolerogenic injection of a protein antigen is given experimentally, it can be shown that
A. B-cell tolerance is more rapidly induced than T-cell tolerance.
B. B-cell tolerance is lost as new B cells come from the bone marrow.
C. B-cell tolerance can be induced only when low doses are used.
D. T-cell tolerance can be induced only when high doses are used.
E. T-cell tolerance is shorter lasting than B-cell tolerance.
7. Blocking any of the following processes can result in peripheral tolerance in mature T cells
except
A. the interaction of costimulatory molecules on T cells with their ligands on APC.
B. intracellular signal transduction mechanisms.
C. negative selection of thymocytes.
D. activation of the IL-2 gene.
E. the binding of antigen with MHC molecules.


31
Chapter 11: Control Mechanisms in the Immune Response
Answers to Review Questions
1. D Negative selection generally ensures that a lymphocyte expressing a receptor reactive to a
self-protein is inactivated by deletion or anergy.
2. C B cells express Fas but not FasL.
3. D Tolerance can be induced only in lymphocytes that express an antigen-specific receptor.
4. D Preexisting antibody may exert a negative feedback on the subsequent response to
antigen.
5. A Injection into muscle and in the presence of adjuvant are likely ways to induce activate
rather than tolerize the immune response. The remaining procedures generally induce tolerance.
The use of cyclosporine in blocking transplantation rejection is discussed further in Chapter 19.
6. B T-cell tolerance is more rapidly achieved, occurs with lower doses, and lasts longer than
B-cell tolerance. As new B cells are produced by the bone marrow, tolerance in this
compartment wanes. T-cell tolerance, by contrast, persists because the thymus of an adult no
longer actively produces new T cells.
7. C Interfering with negative selection of thymocytes disrupts central rather than peripheral T
cell tolerance.


32
Chapter 12: Cytokines
Review Questions
For each question, choose the ONE BEST answer or completion.
1. Which of the following statements regarding the functional properties of cytokines is false?
A. They typically have pleiotropic properties.
B. They often exhibit functional redundancy.
C. They often display antigen specificity.
D. They exhibit synergistic or antagonistic properties.
E. They assist in the regulation and development of immune effector cells.
2. When IL-2 is secreted by antigen-specific T cells activated due to presentation of antigen by
APCs, what happens to naïve antigen-nonspecific T cells in the vicinity?
A. They proliferate due to their exposure to IL-2.
B. They often undergo apoptosis.
C. They begin to express IL-2 receptors.
D. They secrete cytokines associated with their TH phenotype.
E. Nothing happens.
3. Which of the following cytokines have receptors that exhibit structural similarity that helps to
account for their functional redundancy?
A. IL-3, IL-15, and GM-CSF
B. IL-1, IL-2, and M-CSF
C. IL-2, IL-3, and IL-8
D. IL-3, TNF-, and RANTES
E. IL-3, IL-4, and IFN-
4. What type of immune response is not mediated by the TH1 subset?
A. responses to viral infections
B. delayed-type hypersensitivity
C. activation of cytotoxic T cells
D. activation of IgE synthesis
E. responses to intracellular pathogens


33
5. IL-1, IL-6, and TNF-are pro-inflammatory cytokines that are known to
A. cause increased vascular permeability.
B. act in concert with chemokines to promote migration of inflammatory cells to sites of
infection.
C. initiate acute-phase responses.
D. have endogenous pyrogen properties.
E. All of the above.
6. Which of the following cytokines plays a role in terminating inflammatory responses?
A. IL-2
B. IL-4
C. TGF-
D. IFN-
E. IL-3
7. All of the following are induced by the chemokine IL-8 except
A. activation of neutrophils.
B. attraction of neutrophils to sites of tissue damage.
C. wound healing.
D. extravasation of neutrophils.
E. reduction of cytokine production by TH1 cells.
8. Superantigens cause a burst of cytokine production by T cells due to their ability to
A. crosslink the Vsegments of T cell receptors with class II MHC molecules on APCs.
B. crosslink the Vsegments of T cell receptors with class II MHC molecules on APCs.
C. crosslink T cell receptors and CD3.
D. crosslink multiple cytokine receptors on a large population of T cells.
E. crosslink CD3.
__________________________________________________ __________________________
Case Study
A 7-year-old boy with an infected wound on his leg is admitted to the emergency department. His
mother states that a high fever with diarrhea occurred during the last 12 hours. Within the last 2 hours
he had become very lethargic, was unable to stand, and was very disoriented. The attending physician
observes that his blood pressure is dangerously low, and suspects that the boy is suffering from bacterial
septic shock caused by the wound infection. Discuss the etiology of bacterial septic shock, as well as
the role of cytokines in the pathogenesis of this disease. Speculate on future therapeutic strategies that
might be employed by using monoclonal antibodies or other biologic agents to treat this disease.


34
Chapter 12: Cytokines
Answers to Review Questions
1. C Cytokines secreted by a single lymphocyte following antigen-specific activation do not
exhibit antigen specificity. Instead, they regulate the activities of other cells involved in an
immune response by binding to cytokine receptors expressed by these cells.
2. E Since these cells have not been activated by antigen, they do not express the high affinity
IL-2 receptor. Hence they remain quiescent.
3. A The receptors for IL-3, IL-5, and GM-CSF contain the common chain, which is
responsible for signal transduction. Therefore, cytokine binding to each of these receptors
probably induces a similar activation signal.
4. D The TH1 subset is responsible for classical cell-mediated functions (answers A, B, C, and
E). Synthesis of IgE is mediated by cytokines produced by TH2 cells.
5. E The answer is self-explanatory.
6. C Among the cytokines listed, TGF-plays a role in terminating inflammatory responses
by promoting the accumulation and proliferation of fibroblasts and the deposition of extracellular
matrix proteins required for tissue repair.
7. E IL-8 chemotactically attracts and activates neutrophils and induces their adherence to
vascular endothelium. Thus, IL-8 also plays an important role in wound healing. It also
promotes their extravasation into tissues. It plays no role in regulation of cytokine production by
TH1 cellsa biologic property ascribed to IL-10 produced by TH2 cells.
8. A Superantigens bind simultaneously to class II MHC molecules and to the Vdomain of
the T cell receptor activating all T cells bearing a particular Vdomain. Thus, they activate
large numbers of T cells (between 5% and 25%), regardless of their antigen specificity, causing
them to release harmful quantities of cytokines.
__________________________________________________ __________________________
Answer to Case Study
Bacterial septic shock is a condition that can develop within a few hours following infection by certain
gram-negative bacteria, including Escherichia coli, Klebsiella pneumonia, Pseudomonas aeruginosa,
Enterobacter aerogenes, and Neisseria meningitidis. The symptoms are often fatal and include a drop in
blood pressure, fever, diarrhea, and widespread blood clotting in various organs. It develops when
bacterial cell wall endotoxins stimulate macrophages to overproduce IL-1 and TNF-. Therapeutic
strategies using monoclonal antibodies capable of neutralizing the effects of IL-1 and TNF-or
antagonists such as IL-1 receptor antagonist (IL-1Ra) may offer hope for the treatment of bacterial
septic shock in humans.

35
Chapter 13: Complement
Review Questions
For each question, choose the ONE BEST answer or completion.
1. A patient is admitted with multiple bacterial infections and is found to have a complete absence
of C3. Which complement-mediated function would remain intact in such a patient?
A. lysis of bacteria
B. opsonization of bacteria
C. generation of anaphylatoxins
D. generation of neutrophil chemotactic factors
E. None of the above.
2. Which of the following screening tests would be most useful for confirming a presumptive
diagnosis of a congenital absence of a complement component?
A. quantitation of serum opsonic activity
B. quantitation of serum hemolytic activity
C. quantitation of C3 content of serum
D. quantitation of C1 content of serum
E. electrophoretic analysis of patient's serum
3. Complement is required for
A. lysis of erythrocytes by lecithinase.
B. NK-mediated lysis of tumor cells.
C. phagocytosis.
D. bacteriolysis by specific antibodies.
E. All of the above.
4. Which of the following is associated with the development of systemic lupus erythematosus
(SLE)?
A. deficiencies in C1, C4, or C2
B. deficiencies in C5, C6, or C7
C. deficiencies in the late components of complement
D. increases in the serum C3 level
E. increases in the levels of C1, C4, or C2
5. Active fragments of C5 can lead to the following, except
A. contraction of smooth muscle.
B. vasodilation.
C. attraction of leukocytes.
D. attachment of lymphocytes to macrophages.
E. All of the above.


36
6. The alternative pathway of complement activation is characterized by the functions listed below,
except
A. activation of complement components beyond C3 in the cascade.
B. participation of properdin.
C. generation of anaphylatoxin.
D. use of C4.
7. Decay-accelerating factor (DAF) regulates the complement system to prevent complement-mediated
lysis of cells. This involves
A. dissociation of C4b2a or the C3bBb enzyme complex.
B. blocking the binding of C3 convertase to the surface of bacterial cells.
C. inhibiting the membrane attack complex from binding to bacterial membranes.
D. acting as a cofactor for the cleavage of C3b.
E. causing dissociation of C5 convertase.
8. The following activate(s) the alternative pathway of complement:
A. lipopolysaccharides
B. some viruses and virus-infected cells
C. fungal and yeast cell walls (zymosin)
D. many strains of gram-positive bacteria
E. All of the above.
9. Which component(s) of complement could be missing and still leave the remainder of the
complement system capable of activation by the alternative pathway?
A. C1, C2, and C3
B. C3 only
C. C2, C3, and C4
D. C1, C2, and C4
E. C1, C3, and C4
10. An antigenantibody immune complex in a C3-deficient individual will still result in
A. anaphylatoxin production.
B. depression of factor B.
C. production of chemotactic factors.
D. activation of C2.
E. activation of C5.


37
Chapter 13: Complement
Answers to Review Questions
1. E All these functions are mediated by complement components that come after C3 and in
its absence cannot be activated.
2. B The hemolytic assay would reveal a defect in any one of the complement components,
since all are required to effect hemolysis. The tests for specific components are likely to work
only if you happen to pick the right one. They are not useful for screening. Electrophoretic
analysis is good for the major serum components (albumin and globulin), but unlikely to give
information on many of the complement components.
3. D Complement is required for lysis of bacteria by specific anti-bacteria IgM or IgG.
Complement is not required for phagocytosis or lysis of erythrocytes by lecithinase. However,
the C3b opsonins, that are generated during complement activation, enhance phagocytosis of the
opsonized particle. Although some tumor cells can initiate the alternate pathway of complement
activation, complement plays no role in NK-mediated lysis of these cells.
4. A Inherited homozygous deficiency of the early proteins of the classical complement
pathway (C1, C4, or C2) are strongly associated with the development of systemic lupus
erythematosus (SLE). Such deficiencies probably result in abnormal processing of immune
complexes in the absence of a functional classical pathway of complement fixation. Serum
levels of C3 or C4 decrease in SLE due to the large number of immune complexes that bind to
them. Deficiencies in the late components are associated with recurrent infections with pyogenic
organisms.
5. D C5a is an anaphylatoxin, which induces degranulation of mast cells, resulting in the
release of histamine, causing vasodilation and contraction of smooth muscles. C5a is also a
chemotaxin, attracting leukocytes to the area of its release where the antigen is reacting with
antibodies and activates the complement system. It does not promote the attachment of
lymphocytes to macrophases.
6. D The alternative pathway of complement activation connects with the classical pathway at
the activation of C3. Thus, it does not require C1, C4, or C2. Properdin is essential for the
activation through the alternative pathway, since it stabilizes the complex (C3bBb) formed
between C3b and activated serum factor B, which acts as a C3 convertase and activates C3.
During the activation of the alternative pathway, both C3a and C5a are generated; both are
anaphylatoxins and cause degranulation of mast cells.
7. A As a cell surface regulator of complement activation, DAF destabilizes both the alternate
and classical pathway C3 convertases (C4b2a or C3bBb). Like the other regulators of
complement activation (RCA), including CR1, factor H, and C4bBP, these proteins accelerate
decay (dissociation) of C3 convertase, releasing the component with enzymatic activity (C2a or
Bb) from the component bound to the cell membrane (C4b or C3b).
8. E Each of the pathogens and particles of microbial origin listed can initiate the alternate
pathway of complement activation. Parasites (e.g., trypanosomes) and teichoic acid from gram-positive
cell walls can also activate complement using this pathway.


38
9. D C3 is required for the alternative pathway of complement activation, while C1, C2, or C4
are not required.
10. D The immune complex will activate C2 (and C4), but will not activate C3 or any other
components. Since the alternative pathway of complement activation also requires C3, this
pathway will not be activated. Anaphylatoxins and chemotactic factor generation require C3,
while the synthesis of factor B is not related to C3.

39
Chapter 14: Hypersensitivity Reactions: Antibody-Mediated (Type I) Reactions
Review Questions
For each question, choose the ONE BEST answer or completion.
1. The usual sequence of events in an allergic reaction is as follows:
A. The allergen combines with circulating IgE, and the IgE:allergen complex binds to the
mast cells.
B. The allergen binds to IgE fixed to mast cells.
C. The allergen is processed by antigen-presenting cells and the binds to histamine
receptors.
D. The allergen is processed by antigen-presenting cells and the binds to mast cells.
E. The allergen combines with IgG.
2. Epinephrine
A. causes bronchodilation.
B. is effective even after anaphylactic symptoms commence.
C. relaxes smooth muscle.
D. decreases vascular permeability.
E. All of the above.
3. A human volunteer agrees to be passively sensitized with IgE specific for a ragweed antigen
(allergen). When challenged with the allergen intradermally, he displayed a typical skin reaction
due to an immediate hypersensitivity reaction. If the injection with sensitizing IgE was preceded
by an injection (at the same site) of Fc fragments of human IgE followed by intradermal injection
with allergen, which of the following outcomes would you predict?
A. No reaction would occur because the Fc fragments would interact with the allergen and
prevent it from gaining access to the sensitized mast cells.
B. No reaction would occur because the Fc fragments would interact with the IgE antibodies
making their antigen-binding sites unavailable for binding to antigen.
C. No reaction would occur because the Fc fragments would interact with Fcreceptors on
mast cells.
D. The reaction would be exacerbated due to the increased local concentration of IgE Fc
fragments.
E. The reaction would be exacerbated due to the activation of complement.


40
4. The following mechanism(s) may be involved in the clinical efficacy of desensitization therapy
to treat patients with allergies to known allergens:
A. enhanced production of IgG, which binds allergen before it reaches mast cells
B. skewing of T cell responses from TH2 to TH1
C. decreased sensitivity of mast cells and basophils to degranulation by allergen
D. decreased production of IgE antibody
E. All of the above.
5. Immediate hypersensitivity skin reactions
A. usually occur within 24 hours.
B. exhibit a raised wheal due to infiltration by mononuclear cells.
C. exhibit a red flare due to vasodilation.
D. cannot be elicited by monovalent haptens.
E. All are correct.
6. Mast cells
A. are found circulating in the blood.
B. release their granules following lysis.
C. are basophilic after complete degranulation.
D. are very similar to basophils.
E. All are correct.
7. Antihistamines
A. bind to receptors for histamine, thereby preventing the histamine from exerting a
pharmacologic effect.
B. are more effective given before, rather than after, the onset of allergic symptoms.
C. do not influence the activity of leukotrienes.
D. do not affect binding of IgE to mast cells.
E. All are correct.
8. In the RAST assay for ragweed pollen
A. the patient's serum is first mix

[ArchivalUser]

thanks,iren

[ArchivalUser]

hi, iren

thx!
where did you get it, from kaplan or uw? do you have the ans?

[ArchivalUser]

Ans r right in front of your eyes.