Deck 8: T-Cell Development

Question 1

Committed lymphocyte progenitors originate in the

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

Answer 1

B

Question 2

Name that cell.I am a small, nonproliferating cell found within the thymic cortex and contain CD4 and CD8 on my cell surface.

A)DN thymocyte
B)DP thymocyte
C)Thymocyte
D)DN1 cell
E)DN4 cell

Answer 2

B

Question 3

What term BEST describes a selection process against those cells whose T-cell receptors bind too strongly to self-peptide/MHC combinations?

A)Positive selection
B)Negative selection
C)Lineage commitment
D)Hematopoietic commitment to the T-cell lineage
E)None of the above is correct.

Answer 3

B

Question 4

Which stage of DN selection is characterized by rapid proliferation of thymocytes in the subcapsular cortex of the thymus and suppression of TCR rearrangement?

A)DN1
B)DN2
C)DN3
D)DN4
E)None of the answers are correct.

Question 5

Hematopoietic stem cells cultured in the presence of which receptor differentiate into T cells rather than B cells?

A)CD4
B)CD8
C)Notch ligand
D)B7-1
E)CD3

Question 6

Which of the following molecules would double-negative T cells fail to express?

A)CD3
B)CD4
C)MHC class I
D)TAP
E)All of the answers are correct.

Question 7

Signaling through the pre-TCR occurs as a result of

A)binding to MHC class I.
B)binding to MHC class II.
C)binding to either MHC class I or MHC class II.
D)successful assembly of the pre-TCR.
E)expression of CD4.

Question 8

At what stage of T-cell development is the pre-TCR expressed?

A)DN
B)DP
C)SP
D)Pro-T cell
E)None of the answers are correct.

Question 9

Signaling through the pre-TCR results in

A)maturation to the DN4 stage.
B)suppression of TCR - ? chain rearrangement.
C)cessation of proliferation.
D)TCR - ? chain rearrangement.
E)All of the answers are correct.

Question 10

Which of the following represents the EARLIEST stage in T-cell development?

A)DP
B)DN
C)SP-CD4
D)SP-CD8
E)Mature T cell

Question 11

T cells selected on a b haplotype thymus would be able to respond to antigen presenting on which of the following haplotype antigen presenting cells?

A)a
B)b
C)a x b
D)All of the answers are correct.
E)None of the answers are correct.

Question 12

Injecting a TCR transgenic mouse with the peptide that it recognizes would result in an increase in which process?

A)Positive selection
B)Negative selection
C)Complement fixation
D)Phagocytosis
E)All of the answers are correct.

Question 13

MHC^a mice that are irradiated and reconstituted with MHC^{a x b} bone marrow would accept grafts from which of the following donors?

A)MHC^a
B)MHC^b
C)MHC^{a x b}
D)All of the answers are correct.
E)None of the answers are correct.

Question 14

In negative selection, cells that receive _____ signal through their antigen receptors die.

A)a weak
B)a strong
C)an intermediate
D)no
E)intermittent

Question 15

What happens to autoreactive cells that escape the thymus?

A)They attack self-tissues.
B)They can be rendered anergic.
C)They negatively regulate other autoreactive cells.
D)They require TCR ligation and costimulation to be activated.
E)All of the answers are correct.

Question 16

How do self-antigens that are specific to tissues away from the thymus (like insulin or keratin for example) get in the thymus so that developing T cells that react to them can be deleted?

A)Dendritic cells pick them up in the periphery and carry them to the thymus.
B)Specialized macrophages in the thymus filter the bloodstream and present antigens found there to developing T cells.
C)A transcription factor, AIRE, is expressed in thymic medullary epithelial cells, which allows these cells to express proteins normally found in other tissues.
D)They do not get to the thymus, all tissue-specific T cells are deleted in the periphery.
E)There are special chaperone proteins that bind to peripheral proteins and carry them to the thymus.

Question 17

Superantigens differ from regular peptide antigens because they

A)bind outside the peptide-binding groove.
B)activate a larger proportion of T cells.
C)interact with the V ? domain of the TCR.
D)can result in toxic shock.
E)All of the answers are correct.

Question 18

What is currently the BEST explanation for what determines whether a T cell develops into a CD8⁺ T cell or a CD4⁺ T cell?

A)CD4/TCR coengagement suppresses CD8 expression, and CD8/TCR coengagement suppresses CD4 expression.
B)T cells randomly downregulate CD4 or CD8, and only cells that still bind the appropriate MHC will get a strong enough signal to survive.
C)CD4 or CD8 expression is determined by the strength and duration of the TCR/MHC interaction.
D)CD4 or CD8 expression is predestined in the bone marrow.
E)Only ?? T cells express CD8.

Question 19

Which of the following BEST describes the relationship between natural T_REGs and induced T_REGs?

A)Natural T_REGs differentiate into induced T_REGs in response to stimulation through the TCR.
B)Natural T_REGs are derived from memory T cells, and induced T_REGs differentiate directly from developing thymocytes.
C)Natural T_REGs develop in the thymus, and induced T_REGs develop in the periphery.
D)Natural T_REGs have less diverse TCRs than induced T_REGs.
E)None of the answers are correct.

Question 20

Thymocytes whose TCR preferentially interacts with MHC II generates a continuous signal that initiates which cell type to be generated?

A)CD8⁺ T cells
B)CD4⁺ T cells
C)SP thymocytes
D)DP thymocytes
E)Both CD8⁺ T cells and CD4⁺ T cells.

Question 21

Which transcription factor is characteristic of T_REG cells?

A)AP-1
B)NFAT
C)NF ? B
D)OCT-1
E)FoxP3

Question 22

T_REGs have been shown to be protective against which of the following conditions?

A)Inflammatory bowel disease
B)HIV disease
C)Influenza infection
D)MRSA
E)Malaria

Question 23

Which item listed below is NOT likely an application of regulatory T-cells that suppresses immune responses?

A)Inhibition of such cells before immunization may enhance responses to vaccines.
B)Elimination of such cells that suppress responses to tumor antigens may enhance antitumor immunity.
C)Increasing the activity of such cells could be useful in autoimmune treatments.
D)Increasing the activity of such cells could be useful in suppressing organ rejections.
E)All the answers are potential applications.

Question 24

As a thymus-settling progenitor enters the thymus, which molecule appears to heavily influence the progenitor to commit to T-cell development?

Question 25

Explain why T cells are more likely to develop into T cells than T cells.

Question 26

In what way do the four double-negative stages of T-cell development demonstrate the organization of T-cell development according to spatial parameters?

Question 27

What are the two major goals of lymphocyte development?

Question 28

T cells are three times more likely to become TCR- cells versus TCR- cells.Why is this the case considering T-cell development mechanisms within the thymus?

Question 29

Compare and contrast the affinity hypothesis and altered peptide hypothesis to explain the thymic selection paradox (why we don't negatively select all cells that we positively select).

Question 30

In your own words, explain why thymic selection is needed?

Question 31

At first glance, the logic of positive selection appears to be lacking.Predict what might happen in the absence of positive thymic selection.

Question 32

A classmate in your immunology course fails to see the importance of discovering AIRE.Can you convince him of the importance of AIRE in understanding T-cell tolerance?

Question 33

Does thymic negative selection always need to involve death of the self-reactive T cell?

Question 34

The affinity model can help explain the thymic selection paradox.What is the paradox, and is the affinity model the only way the paradox can be explained?

Question 35

In a brief statement, can you explain how transcription factors play a role in T-cell lineage commitment?

Question 36

Please list two mechanisms, independent of central tolerance, which can help maintain self-tolerance.Why are such additional mechanisms needed?