T Cell Mediated Immunity

Question 1

Adaptive cell-mediated immunity involves the generation of activated antigen-specific effector
a. antibodies.
b. B cells.
c. cytokines.
d. macrophages
e. T cells.

Answer 1

e. T cells.

Question 2

T cells are activated to armed effector cells when they encounter antigen on
a. blood-borne pathogens.
b. bone marrow stromal cells.
c. professional APC.
d. virus-infected tissues.
e. all of the above.

Answer 2

c. professional APC.

Question 3

T cells move from the circulation into the peripheral lymphoid tissues when they bind
a. antigen.
b. APC.
c. B7.
d. homing molecules.
e. vascular addressins.

Answer 3

e. vascular addressins.

Question 4

LFA-1 is a(n)
a. co-receptor on T cells.
b. co-stimulatory molecule on APC.
c. cytokine receptor on APC.
d. integrin on T cells.
e. vascular addressin on HEV.

Answer 4

d. integrin on T cells.

Question 5

The antigen specificity of Th activation by macrophages is enhanced by the
a. ability of each macrophage to present only specific epitopes to T cells.
b. binding of T cell adhesion molecules only to macrophages presenting the antigen recognized by the T cell.
c. specificity of CD4 binding to Class II MHC on the macrophage.
d. upregulation of CD4 or CD8 co-receptors following antigen binding.
e. upregulation of co-stimulatory molecules only on macrophages which have contacted foreign antigen

Answer 5

e. upregulation of co-stimulatory molecules only on macrophages which have contacted foreign antigen

Question 6

Membrane events required for Th activation include all of the following EXCEPT binding of T cell
a. CD4 to APC Class II MHC.
b. CTLA-4 to APC B7.
c. high affinity IL-2 receptor to IL-2.
d. LFA-1 to APC ICAM.
e. TCR to peptide on APC Class II MHC.

Answer 6

b. CTLA-4 to APC B7.

Question 7

Cytoplasmic signals generated in response to antigen binding and co-stimulatory signals to Tc cells include all of the following EXCEPT
a. activation of transcription factors that upregulate synthesis of IL-2.
b. aggregation of TCR and CD8 in the T cell membrane.
c. increased free intracellular Ca++.
d. induction of RAG synthesis.
e. tyrosine kinase binding to the cytoplasmic domains of CD3 and CD8.

Answer 7

d. induction of RAG synthesis.

Question 8

Th1 cells secrete cytokines which
a. activate macrophages.
b. increase susceptibility to allergic reaction
c. inhibit macrophage secretion of inflammatory cytokines
d. stimulate B cells to secrete neutralizing antibodies
e. stimulate proliferation of Th2 cells

Answer 8

a. activate macrophages.

Question 9

A T cell which binds antigen without undergoing a co-stimulatory signal from an APC
a. becomes inactivated.
b. can become a helper cell but not a killer cell.
c. can get a co-stimulatory signal from a different APC
d. dies.
e. divides but doesn’t make effector molecules.

Answer 9

a. becomes inactivated.

Question 10

Dendritic cells are the best APCs for activating
a. CTL.
b. helper T cells.
c. naïve T cells.
d. Th1 cells.
e. Th2 cells.

Answer 10

c. naïve T cells.

Question 11

Macrophages normally have low levels of B7 and MHC, but express more after they phagocytose
a. bacterial antigens.
b. peptide antigens.
c. Tc cytokines.
d. Th cytokines.
e. viral antigens.

Answer 11

a. bacterial antigens.

Question 12

B cells differ from the other professional APC because B cells
a. activate T cells in the secondary lymphoid organs.
b. present exogenous antigen to T cells on Class II MHC.
c. present only peptides from antigens they bind with their membrane Ig.
d. use B7 as their co-stimulatory molecule.
e. None of the above is true.

Answer 12

c. present only peptides from antigens they bind with their membrane Ig.

Question 13

Once T cells have received antigen plus co-stimulatory signals, they divide in response to IL-2 secreted by
a. B cells.
b. dendritic cells.
c. macrophages.
d. themselves.
e. whichever APC activated them.

Answer 13

d. themselves.

Question 14

The a chain of the IL-2 receptor
a. causes the receptor to associate with TCR in the T cell membrane.
b. changes the specificity of the receptor to bind IFNg.
c. increases the affinity of the receptor for IL-2.
d. increases the signal transduction ITAMs of the receptor.
e. All of the above are true.

Answer 14

c. increases the affinity of the receptor for IL-2.

Question 15

It takes ________________ after antigen contact before T cells are armed effector cells.
a. 5 minutes.
b. 30 minutes.
c. 24 hours.
d. 4-5 days.
e. 7-10 days.

Answer 15

d. 4-5 days.

Question 16

Armed effector T cells differ from naïve T cells in that effector cells
a. are not antigen-specific.
b. do not need to bind co-stimulatory molecules.
c. do not need to bind peptide plus MHC.
d. do not use CAMs to bind other cells.
e. have CD28 instead of CTLA-4 to bind B7.

Answer 16

b. do not need to bind co-stimulatory molecules.

Question 17

The effector molecules of cytotoxic T cells do NOT include
a. Fas.
b. granzymes.
c. IFNg.
d. perforin.
e. TNFb.

Answer 17

a. Fas.

Question 18

Interferons
a. activate B cells to make virus-specific antibodies.
b. are Th2 cytokines.
c. are virus proteins that interfere with activation of cytotoxic T cells.
d. interfere with virus entry into host cells.
e. inhibit virus replication by infected cells.

Answer 18

e. inhibit virus replication by infected cells.

Question 19

The ability of a cytokine to change gene expression in the target cell is influenced by all of the following EXCEPT
a. presence of high-affinity receptors on the target cell.
b. presence of soluble cytokine receptors.
c. proximity of the producing and target cells.
d. rate of transport of cytokine-receptor complexes into the cytoplasm.
e. simultaneous production of another cytokine whose receptor uses the same signal transducing subunit.

Answer 19

d. rate of transport of cytokine-receptor complexes into the cytoplasm.

Question 20

IL-1 is produced by macrophages and acts on the hypothalamus to induce fever. This is an example of ____ cytokine action.
a. autocrine.
b. endocrine.
c. paracrine.
d. pleiotropic.
e. synergistic.

Answer 20

b. endocrine.

Question 21

CD40 on macrophages binding to CD40L on Th1 cells signals the macrophages to
a. die.
b. kill cytoplasmic viruses.
c. phagocytose the Th1 cells.
d. respond to IFNg by expressing more membrane MHC.
e. secrete IL-2.

Answer 21

d. respond to IFNg by expressing more membrane MHC.

Question 22

Activated CTL can regulate immune responses by signaling activated lymphocytes to undergo
a. apoptosis.
b. clonal deletion.
c. clonal proliferation.
d. cytotoxicity.
e. somatic hypermutation.

Answer 22

a. apoptosis.

Question 23

Cellular immunity includes all of the following except
a. activated macrophages killing phagocytosed bacteria.
b. CD8 T cells inducing apoptosis using Fas-FasL binding.
c. complement-mediated lysis of bacterial cells.
d. MHC-restricted cytotoxic T cells killing virus-infected cells.
e. NK cells performing natural killing of tumor cells.

Answer 23

c. complement-mediated lysis of bacterial cells.

Question 24

CTL binding and destruction of target cells depends on
a. a co-stimulatory signal from the target cell.
b. antigen presentation on the surface of the target cell.
c. lack of a negative signal from MHC to prevent cytotoxicity.
d. presence of virus proteins in the membrane of the target cell.
e. secretion of cytokines by the infected cell to attract CTL.

Answer 24

b. antigen presentation on the surface of the target cell.

Question 25

CTL use perforin to
a. activate the classical complement cascade to lyse the target.
b. allow granzymes to enter the target cell and initiate apoptosis.
c. promote target cell lysis by macrophages.
d. stimulate the target cells to express Fas on their membranes
e. substitute for C9 in the alternative complement pathway.

Answer 25

b. allow granzymes to enter the target cell and initiate apoptosis.

Question 26

CTL do not damage uninfected cells because
a. CTL do not bind uninfected cells using their CAMs.
b. granzymes and perforin are secreted only in the space between the CTL and the infected target cells.
c. uninfected cells cannot undergo apoptosis.
d. uninfected cells have no membrane Class I MHC because they have no pathogen peptides to present.
e. None of the above is true.

Answer 26

b. granzymes and perforin are secreted only in the space between the CTL and the infected target cells.

Question 27

Granzymes are
a. enzymes which cut DNA into ladders to induce apoptosis.
b. present in an inactive form in resting CD8 cells.
c. secreted in large amounts by CTL to kill many target cells simultaneously.
d. structurally similar to macrophage cytokines that kill vesicular pathogens.
e. synthesized by CTL before they bind to target cells.

Answer 27

e. synthesized by CTL before they bind to target cells.

Question 28

Which of the following would you NOT expect to result in reduced CTL killing activity?
a. absence of the gene for b2 microglobulin.
b. absence of the gene for HLA DM.
c. absence of the gene for perforin.
d. presence of anti-CD8 antibodies.
e. presence of monoclonal antibodies specific for multiple TCR Va and Vb specificities.

Answer 28

b. absence of the gene for HLA DM.

Question 29

IFNg does all of the following EXCEPT
a. activate macrophages.
b. cut DNA in target cells into 200bp fragments.
c. directly inhibit viral replication in infected cells.
d. induce macrophages to express higher levels of MHC on their membranes.
e. starve intracellular parasites of tryptophan.

Answer 29

b. cut DNA in target cells into 200bp fragments.

Question 30

Macrophage activation by Th1 cells is an important immune mechanism for eliminating
a. bacteria which can resist lysosomal degradation.
b. bacteria whose capsule makes them resistant to phagocytosis.
c. enveloped viruses.
d. parasites that infect T cells.
e. viruses that infect macrophages.

Answer 30

a. bacteria which can resist lysosomal degradation.

Question 31

T cells which activate macrophages do all of the following EXCEPT
a. activate macrophages at the site of infection.
b. activate only macrophages presenting specific antigen on MHC.
c. become activated effector cells in response to antigen plus co-stimulation.
d. have membrane CD4.
e. provide granzymes that the macrophages use to kill vesicular pathogens.

Answer 31

e. provide granzymes that the macrophages use to kill vesicular pathogens.

Question 32

Th1 cells promote cellular immunity by secreting primarily
a. IL-1 and IL-6.
b. IL-2 and IFNg.
c. IL-4 and IL-5.
d. IL-10 and IL-12.
e. TNFa and FasL.

Answer 32

b. IL-2 and IFNg.

Question 33

Macrophages kill pathogens using all of the following EXCEPT
a. nitric oxide.
b. oxygen radicals.
c. perforins.
d. peroxides.
e. proteolytic enzymes.

Answer 33

c. perforins.

Question 34

Th1 cells make IL-3 and GM-CSF, which
a. activate macrophages.
b. induce apoptosis in old macrophages.
c. stimulate macrophages to kill vesicular pathogens.
d. stimulate macrophage production in the bone marrow.
e. None of the above is a function of IL-3 and GM-CSF.

Answer 34

d. stimulate macrophage production in the bone marrow.

Question 35

Granulomas
a. are commonly found in tissues infected with viruses.
b. are granulocyte tumors.
c. are a sign that the body has successfully eliminated all pathogen
d. contain infected macrophages surrounded by T cells.
e. contain infected T cells surrounded by macrophages.

Answer 35

d. contain infected macrophages surrounded by T cells.