Exam 1: Set 3

Question 1

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.

Answer 1

B. The first antibody is specific for the primary amino acid sequence of TT, whereas the
second is specific for conformational determinants.

Question 2

Injection into rabbits of a preparation of pooled human IgG could stimulate production of:

A. anti-γ heavy-chain antibody. B. anti-κ chain antibody.
C. anti-λ chain antibody.
D. anti-Fc antibody.
E. All are correct.

Answer 2

E. All are correct.

Question 3

A polyclonal antiserum raised against pooled human IgA will react with

A. human IgM. 
B. κ light chains. 
C. human IgG. 
D. J chain.
E. All are correct.

Answer 3

E. All are correct.

Question 4

The first immunoglobulin synthesized by the fetus is:

A. IgA.
B. IgE.
C. IgG.
D. IgM.
E. None; the fetus does not synthesize immunoglobulins.

Answer 4

D. IgM.

Question 5

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 isotypes.
D. relatively high levels of IgM often correlate with a first recent exposure to the inducing agent

Answer 5

D. relatively high levels of IgM often correlate with a first recent exposure to the inducing agent

Question 6

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.

Answer 6

E. All of the above.

Question 7

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.

Answer 7

A. covalent bonds.

Question 8

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 lower 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.

Answer 8

A) They will have a lower avidity for HEL as compared with the intact IgG.

Question 9

Which of the following are functions of proteins encoded by of TAP-1 and -2 genes?

A. bind β2-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

Answer 9

D. transport peptides into the endoplasmic reticulum for binding to MHC class I

Question 10

When the sequences of different MHC class I molecules are compared, the variation between molecules is concentrated within which of the following?

A. Areas of the molecule that bind CD4
B. Areas of the molecule that bind to the T cell receptor and to the antigenic peptide C. β-2 microglobulin
D. the transmembrane domain of the α chain
E. the β1 domain (the N terminal domain of the β chain)

Answer 10

B. Areas of the molecule that bind to the T cell receptor and to the antigenic peptide C. β-2 microglobulin

Question 11

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.

Answer 11

A. It is produced primarily by activated macrophages.

Question 12

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

Answer 12

D. activated T cells

Question 13

Which of the following statements about cytokines synthesized by CD4+ TH1 and TH2 subsets is incorrect?

A. Cytokines produced by TH1 cells include IFN-gamma
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 induce proliferation of CD8 + T cells
E. TH2 cell cytokines induce proliferation of B cells

Answer 13

D. TH2 cells secrete cytokines that induce proliferation of CD8 + T cells

Question 14

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

Answer 14

D. vaccinia-infected cells expressing the same MHC class I molecules as the individual

Question 15

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
E. None of the above

Answer 15

D. lymphocytes that express a receptor reactive to a self-protein are inactivated by deletion

Question 16

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.

Answer 16

D. Immature neutrophils are more susceptible to tolerance than mature neutrophils.

Question 17

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.

Answer 17

C. They often display antigen specificity.

Question 18

When IL-2 is secreted by antigen-specific T cells activated due to presentation of antigen by APCs, what happens to naive antigen-nonspecific T cells in the vicinity?

A. They proliferate due to their exposure to IL-
B. They often undergo apoptosis.
C. They begin to express IL-2 receptors.
D. They secrete cytokines associated with their T H phenotype.
E. Nothing happens.

Answer 18

E. Nothing happens.

Question 19

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.

Answer 19

E. None of the above.

Question 20

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.

Answer 20

D. bacteriolysis by specific antibodies.

Question 21

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

Answer 21

B. quantitation of serum hemolytic activity

Question 22

Soluble fragments of C5 can lead to the following, except:

A. contraction of smooth muscle.
B. vasodilation.
C. attraction of leukocytes.
D. phagocytosis.
E. All of the above.

Answer 22

D. phagocytosis.

Question 23

The alternative pathway of complement activation is characterized by the functions listed below, except:

A. use of C3 component
B. activation of complement components beyond C3 in the cascade.
C. participation of properdin.
D. generation of anaphylatoxin.
E. use of C1 component

Answer 23

E. use of C1 component

Question 24

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.

Answer 24

A. dissociation of C4b2a or the C3bBb enzyme complex.

Question 25

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

Answer 25

D. C1, C2, and C4