Deck 10: T-Cell Activation, Differentiation, and Memory

Question 1

What event initiates an adaptive immune response?

A)The interaction of a B cell with a T_H cell
B)The expression of cytokines CD4 or CD8
C)The production of MHC class I or II molecules
D)The interaction of a naïve T cell with an antigen-presenting cell
E)The phagocytosis of a pathogen by a macrophage

Answer 1

D

Question 2

Which of the following molecules provide costimulatory signals to naïve T cells?

A)CD28
B)ICOS
C)CTLA-4
D)PD-1
E)Both CD28 and ICOS are correct.

Answer 2

E

Question 3

For pathogen peptides to be seen as foreign, they must be displayed on a T cell in the context of a(an)

A)B-cell marker.
B)CD molecule.
C)IgM molecule.
D)MHC peptide.
E)Pattern-recognition receptor molecule.

Answer 3

D

Question 4

CD4⁺ T cells recognize

A)CD8⁺ markers.
B)IgM.
C)MHC class I peptides.
D)MHC class II peptides.
E)both MHC class I and class II peptides.

Question 5

CD8⁺ T cells exposed to MHC class I peptides are

A)cytotoxic T cells.
B)helper T cells.
C)natural killer cells.
D)dendritic T cells.
E)both cytotoxic T cells and helper T cells.

Question 6

CD4⁺ T cells become helper T cells in response to

A)exposure to antigen.
B)exposure to MHC class II peptide.
C)exposure to any MHC peptide.
D)exposure to MZ B cells.
E)exposure to TNF- ?

Question 7

Naïve CD4⁺ and CD8⁺ T-cells leave the _____ and enter circulation.

A)bone marrow
B)liver
C)lymph node
D)spleen
E)thymus

Question 8

A naïve T-cell refers to a T cell that

A)does not express CD4⁺ or CD8⁺.
B)has not left the bone marrow.
C)has not yet encountered an antigen.
D)is not mature.
E)resides in the thymus.

Question 9

Bonds formed between the T cell and a dendritic cell are relatively weak.Which of the following help to strengthen this association so that a T cell can see which antigen is being presented by a dendritic cell?

A)CD28/LFA-5
B)CD 28
C)ICAM-1/LFA-1
D)IL-2R
E)Pattern-recognition molecules

Question 10

Which of the following is required for T-cell activation?

A)Antigen-specific TCR binding to MHC peptide
B)Expression of CD4⁺ or CD8⁺
C)Interaction with CD80, CD86, or ICOS-L
D)Both antigen-specific TCR binding to MHC peptide and expression of CD4⁺ or CD8⁺ are correct.
E)Both antigen-specific TCR binding to MHC peptide and Interaction with CD80, CD86, or ICOS-L are correct.

Question 11

Coreceptor molecules are required by T_C and T_H cells so that the TCR can stably bind to the MHC peptide presenting the antigen.All of the following are coreceptor molecules common to both T_C and T_H cells and their respective antigen-presenting cells EXCEPT

A)CD2/LFA-3.
B)CD28/B7.
C)CD45R/CD22.
D)LFA-1/ICAM-1.
E)All of the answers are correct.

Question 12

CTLA-4 is a costimulatory receptor on T cells that belongs to the same family as the CD28 costimulatory receptor.However, CTLA-4 is antagonistic to CD28.Which of the following could be a functional advantage of CTLA-4 expression within the immune response?

A)CTLA-4 competes with CD28 for ligand binding so that, if CD28 binds to its ligand, the response will be magnified.
B)CTLA-4 is often given to immunosuppressed individuals to trigger an immune response.
C)CTLA-4 limits the immune response of T_C and T_H cells after an infection has been cleared.
D)CTLA-4 limits T_C activity in healthy individuals during a viral infection.
E)CTLA-4 reduces the lag time between antigen presentation to a T_H cell and B-cell activation.

Question 13

PD-1 is a negative costimulatory signal expressed by tumor cells.What advantage would the expression of PD-1 have in a tumor cell avoiding the immune response?

A)Tumor cells can avoid being killed by activated T_C cells.
B)Tumor cells can avoid apoptosis triggered by T_H cells.
C)Tumor cells avoid phagocytosis by dendritic cells.
D)Tumor cells are stimulated to reproduce faster than tumor cells that do not express PD-1.
E)None.Tumor cells are recognized as self and, therefore, do not pose a health threat.

Question 14

T cells are frequently at fault for causing damage in autoimmune disorders and in transplant rejection.As an immunologist, your dream is to discover a method for decreasing T-cell response to self-antigens.Which of the following would be the BEST target for your research?

A)Activated B cells because they make T-cell receptor molecules
B)Antibody mediated apoptosis of dendritic cells
C)CTLA-4 antagonists that block the action of CTLA-4
D)Ligands that block the binding of one costimulatory molecule
E)Radiation therapy directed at all T cells

Question 15

T-cell activation requires antigen being displayed in the context of an APC and interaction between costimulatory molecules on the APC and the T cell.In addition to these two signals, T-cell activity is often influenced by cytokines.Which of the following is an example of how cytokines can influence T-cell activity in the presence of MHC presentation and costimulatory ligand interaction?

A)CD28 causes memory NK cells to be produced.
B)CD8 triggers apoptosis in T cells that recognize self-antigens.
C)IL-2 triggers T-cell proliferation.
D)Opsonins recruit eosinophils to present carbohydrate antibodies to naïve T_C cells.
E)TNF- ? increases the production of IgM by activated T cells.

Question 16

Which type of professional antigen-presenting cells is a naïve T cell MOST likely to encounter?

A)B cell
B)Dendritic cell
C)Macrophage
D)Either B cell or dendritic cell
E)Either dendritic cell or macrophage

Question 17

TSST-1 is a protein produced by some species of bacteria that acts as a superantigen.What ligand does TSST-1 bind?

A)T-cell receptor
B)MHC class I
C)MHC class II
D)Both T-cell receptor and MHC class I
E)Both T-cell receptor and MHC class II

Question 18

With respect to T-cell activation, effector molecules trigger all of the following functions EXCEPT

A)cell-cycle entry.
B)cell division to produce additional T cells.
C)cell differentiation into various types of T cells.
D)cell stimulation of B cells.
E)cell survival.

Question 19

Which helper T-cell subset is MOST likely to be preferentially generated in response to a virus?

A)T_H17
B)T_H1
C)T_REG
D)T_H22
E)None of the answers are correct.

Question 20

Which type of T cell directs and regulates B-cell activity and differentiation?

A)Memory T
B)NK
C)T_C
D)T_H1
E)T_H2

Question 21

Which type of T helper cell regulates allergic reactions and protects against extracellular pathogens?

A)T_H1
B)T_H2
C)T_H17
D)T_REG
E)T_FH

Question 22

Which type of T helper cell inhibits inflammation?

A)T_H1
B)T_H2
C)T_H17
D)T_REG
E)TF_H

Question 23

Which of the following are characteristics of naïve CD4⁺ and CD8⁺ T cells as they leave the thymus and enter the circulation (prior to antigen stimulation)?

A)Condensed chromatin
B)Exhibit little transcriptional activity
C)High mobility
D)Very little cytoplasm relative to nucleus
E)All of the answers are correct.

Question 24

Costimulatory signals are required to achieve optimal T-cell activation (via exposure to antigen) and are considered part of which of the three steps essential to this process?

A)Signal 1
B)Signal 2
C)Signal 3
D)Both signal 1 and signal 2
E)Both signal 2 and signal 3

Question 25

Which cells are capable of providing both signal 1 and signal 2 to a naïve T cell?

A)Dendritic cell
B)Macrophage
C)B cells
D)All of the answers are correct.
E)None of the answers are correct.

Question 26

Cross-regulation of various members of a subset of T cells is frequently observed with

A)all T_C cells.
B)all T_H cells.
C)only T_C1 subset.
D)only T₁ subset.
E)only T_REG subset.

Question 27

All of the following are functions of T_H1 cells EXCEPT:

A)contributes to autoimmunity.
B)enhances APC activity.
C)enhances T_C activity.
D)involved with delayed type hypersensitivity reactions.
E)protects against intracellular pathogens.

Question 28

T_H17 cells are involved with all of the following EXCEPT

A)autoimmunity.
B)delayed-type hypersensitivity.
C)inflammatory response.
D)protection against fungal infections.
E)protection against bacterial infections.

Question 29

Follicular helper T cells are a recent discovery in the helper T-cell lineage.What is the primary role of T_FH cells?

A)To help B-cell development in germinal centers
B)To regulate T_REG cell activity
C)To stimulate dendritic cell production
D)To suppress B-cell activation after pathogen has been cleared
E)To suppress T_C cells after an infection has been cleared

Question 30

Mycobacterium leprae, the causative agent of leprosy in humans, is an intracellular pathogen that resides in the phagosome of macrophages.Leprosy presents in two main clinical manifestations.Tuberculoid leprosy results in the formation of granulomas and a cell-mediated immune response, whereas lepromatous leprosy results in the production of high levels of IgG (hypergammaglobulinemia).If T_H2 is produced in high levels during an M.leprae infection, which type of leprosy would result?

A)Lepromatous leprosy
B)Tuberculoid leprosy
C)Either lepromatous leprosy or tuberculoid leprosy
D)Neither; leprosy depends on the expression of T_REG cells
E)Cannot determine; insufficient clinical evidence to support either outcome

Question 31

Which of the following is MOST likely to stimulate a memory T cell?

A)B cell
B)Dendritic cell
C)Memory cell
D)All of the answers are equally likely to stimulate a memory T cell.
E)None of the answers will stimulate a memory T cell.

Question 32

What is the function of a memory T cell?

A)To activate T_C and T_H cells during an active primary infection
B)To avoid autoimmune disorders by producing memory for self-antigens during T-cell development
C)To maintain an active T-cell response (T_C or T_H) after an infection is cleared
D)To provide an almost immediate response upon subsequent exposure to a specific pathogen
E)To suppress T_C activity after a pathogen is cleared

Question 33

Which cell type can activate a memory T cell?

A)B cell
B)Dendritic cell
C)Macrophage
D)All of the answers are correct.
E)None of the answers is correct.

Question 34

Memory T cells, effector T cells, and naïve T cells share several characteristics.Which of the following descriptions could ONLY be said of memory T cells?

A)Memory T cells are activated by any APC.
B)Memory T cells are only found in one location and do not circulate.
C)Memory T cells express CD44, CD62L, and CCR7.
D)Memory T cells recognize MHC class I or class II peptides displaying antigen molecules.
E)Memory T cells depend upon costimulatory signals from CD2/ LFA-3, CD45R/ CD22, and LFA-1/ ICAM-2.

Question 35

Naïve T cells are highly mobile and continuously circulate our blood, lymph, and secondary organs while scanning for stimulating antigens.Speculate the rationale for the large-scale mobility phenotype.

Question 36

You have just been infected with an intracellular bacterial pathogen (such as Listeria monocytogenes).In mounting an immune response against the pathogen, which subset of CD4⁺ T cells will be produced preferentially? What polarizing cytokine will favor the production of this subset? What effector cytokine will be produced by this subset?

Question 37

True or False? The sole purpose of CD4 and CD8 molecules is to provide immunologists a means of differentiating between T-cell populations.Explain.

Question 38

Compare costimulatory and co-inhibitory molecules.What are the two major roles of co-inhibitory molecules?

Question 39

CTLA-4 is not constantly expressed on naïve T cells.Is this logical? Explain.

Question 40

Based on your knowledge of CTLA-4 and PD-1, could blocking the activity of these molecules have any potential uses in clinical scenarios? Explain.

Question 41

Endogenous and exogenous superantigens can directly activate the host T-cell response.Why might a pathogen purposely invite a host T-cell response?

Question 42

A family member has been infected by a protozoan pathogen.Using correct terminology, summarize the subset of T cells that is likely to be activated by this type of pathogen?

Question 43

How can advances in understanding how helper T-cell differentiation is regulated be applied to the use of vaccine adjuvants? Explain.

Question 44

Consider memory T-cell subsets.How do the subsets thus far identified differ from one another?