Deck 8: T Cell-Mediated Immunity

Question 1

Which of the following is associated with immature dendritic cells in the skin before their activation?

A)Toll-like receptors
B)CTLA4
C)CCR7
D)DC-SIGN
E)ICAM-3.

Answer 1

A

Question 2

Activated T cells express _____,which binds to B7 with 20 times higher affinity than CD28 and results in _____ of T-cell activity and proliferation.

A)high-affinity IL-2 receptor; stimulation
B)CD40L; suppression
C)VLA-4; stimulation
D)CTLA4; suppression.

Answer 2

D

Question 3

area of contact between membranes of a T cell and an antigen-presenting cell where a clustering of protein-protein interactions occur is called a(n)

A)immunoreceptor tyrosine-based activation motif (ITAM)
B)polarization
C)cross-presentation center
D)granuloma
E)immunological synapse.

Answer 3

E

Question 4

Naive lymphocytes homing to lymphoid tissue use _____ to bind to CD34 and GlyCAM-1 on high endothelial venules.

A)L-selectin
B)CD2 (LFA-2)
C)ICAM-1
D)CCL21
E)CD28.

Question 5

Which of the following describes an activated dendritic cell upon arriving in a lymph node?

A)located in follicles and medulla of the lymph node
B)associated mainly with antigen uptake and processing
C)bears highly elaborated finger-like processes called dendrites
D)expresses low levels of MHC class II molecules
E)carries out apoptosis of lymphocytes.

Question 6

Macrophages exhibit all of the following characteristics except _____.

A)they trap and degrade pathogens in secondary lymphoid organs
B)they deliver co-stimulatory signals to naive T cells needed for T-cell priming
C)they migrate from sites of infection to nearby secondary lymphoid organs
E)they remove and degrade apoptotic lymphocytes from secondary lymphoid tissues
F)they reside in both the cortex and medulla of lymph nodes.

Question 7

Which selectins,mucin-like vascular addressins,and integrins have a role in the circulation of T cells between the blood and lymphoid tissues?
B.Describe in chronological order how T cells migrate across lymph node high endothelial venules (HEVs)from the blood by using these molecules.

Question 8

Unlike innate immune responses,which can begin within hours of the onset of an infection,adaptive immune responses involving T cells usually take several days.What accounts for this delay between the initiation of an infection and the engagement of an adaptive immune response?

Question 9

At which anatomical sites do naive T cells encounter antigen?
B.In which sites specifically would a pathogen or its antigens end up,and how would they be transported to these sites,if they (i)entered the body through a small wound in the skin,(ii)entered the body from the gut,or (iii)got into the bloodstream?
C.How do naive T cells arrive at these sites?
D.Do all T cells leave these locations after priming,and if so,how?

Question 10

co-stimulatory molecule _____ on professional antigen-presenting cells binds _____ on the surface of naive T cells.

A)DC-SIGN; ICAM-3
B)B7; CD28
C)ICAM-1; LFA-1
D)MHC class II; T-cell receptor
E)MHC class II; CD4.

Question 11

Identify three types of professional antigen-presenting cell.
B.How are they distributed in secondary lymphoid tissue?
C.Which kinds of antigen do they present efficiently to T cells?

Question 12

Explain the functional differences between immature and mature dendritic cells.
B.Discuss why you think these functional changes should occur.

Question 13

Explain what feature of B cells makes them useful as professional antigen-presenting cells in an immune response.

Question 14

are Toll-like receptors (TLRs)important for adaptive immune responses?

Question 15

Which cell-surface glycoprotein distinguishes professional antigen-presenting cells from other cells and is involved in the co-stimulation of T cells?
B.What receptors can it bind on the T cell and what signal does it deliver in each case?
C.Explain the consequence of antigen recognition by T cells in the absence of this glycoprotein on the antigen-presenting cell.

Question 16

are dendritic cells so important in adaptive immune responses? Explain what they do.

Question 17

adhesion molecule called _____ is expressed exclusively on activated dendritic cells and binds to _____ on naive T cells in the T-cell areas of secondary lymphoid tissue.

A)DC-SIGN; ICAM-3
B)CD2; LFA-3
C)MHC class II; T-cell receptor
D)L-selectin; GlyCAM-1
E)ICAM-1; LFA-1.

Question 18

of the following are correctly matched except _____.

A)T_H1: T-bet
B)T_reg: FoxP3
C)IL-12: dendritic cells
D)T_H17: RORγT
E)T_H2: Bcl6.

Question 19

Which of the following is produced by CD8 T cells?

A)IL-10
B)TGF-β
C)IFN-γ
D)IL-4
E)IL-17

Question 20

release of lytic granules from cytotoxic T cells is aimed specifically at infected target cells while preserving the integrity of neighboring,uninfected cells.This is best explained by the observation that _____.

A)only target cells bearing appropriate peptide:MHC class I complexes are susceptible to necrosis
B)redistribution of lytic granules in the T cell delivers them to confined areas on the target cell in contact with the T cell
C)regulatory T cells deliver survival signals to uninfected neighboring cells that renders them resistant to cytotoxins
D)the amount of cytotoxins in a given cytotoxic T cell is so limited that only the cell closest to the T cell will succumb to the effects of perforin and granzyme
E)uninfected cells are highly resistant to the effects of cytotoxins.

Question 21

Talin is best described as a _____.

A)protein tyrosine kinase
B)transcriptional activator
C)cytoskeletal protein
D)pro-inflammatory cytokine
E)cytokine receptor that associates with Janus kinases (JAKs).

Question 22

Which of the following is not produced by T follicular helper (T_FH)cells?

A)CD4
B)IL-4
C)IFN-γ
D)TNF-α
E)IL-21

Question 23

Which of the following statements is false regarding CD8 T cells?

A)CD8 T cells have only one effector function,which is cytotoxicity.
B)Compared with naive CD4 T cells,naive CD8 T cells have more stringent requirements for co-stimulatory activity.
C)Effector CD8 cells require co-stimulation to kill their target cells.
D)The most potent antigen-presenting cell for naive CD8 T cells is the dendritic cell.

Question 24

enzyme that generates diacylglycerol (DAG)and inositol trisphosphate (IP₃)from phosphatidylinositol bisphosphate (PIP₂)is _____.

A)protein kinase C-θ (PKC-θ)
B)calcineurin
C)phospholipase C-γ (PLC-γ)
D)protein tyrosine kinase ZAP-70
E)protein tyrosine kinase Lck

Question 25

of the following indicate correct intermolecular associations except _____.

A)Janus kinases (JAKs): serglycin
B)L-selectin: GlyCAM-1
C)VLA-4: VCAM-1
D)JAKs: signal transducers and activators of transcription (STATs)
E)CD40: CD40 ligand.

Question 26

primary effect of inositol trisphosphate (IP₃)during T-cell activation is to _____.

A)cause an increase in cytosolic calcium concentration
B)activate phospholipase C-γ
C)activate a MAP kinase cascade
D)facilitate the differentiation of immature effector T cells
E)align the microtubule-organizing center toward the antigen-presenting cell.

Question 27

a non-professional antigen-presenting cell that lacks co-stimulatory molecules presents peptide:MHC complexes to a T cell specific for that peptide,then _____.

A)the T cell delivers a signal to the non-professional antigen-presenting cell to activate the expression of co-stimulatory molecules.
B)the T cell begins to express the α chain of the IL-2 receptor.
C)the T cell differentiates into a T_H1 cell.
D)T-cell tolerance occurs as a result of anergy.
E)the T cell is more heavily reliant on signals transmitted through CD4 or CD8 in order to become activated.

Question 28

of the following statements regarding interleukin-2 (IL-2)or its receptor are true except _____.

A)The low-affinity IL-2 receptor is a membrane-bound heterodimer composed of α and β chains.
B)IL-2 production increases approximately 100-fold if a co-stimulatory signal is delivered.
C)T-cell proliferation occurs upon binding of IL-2 to the high-affinity IL-2 receptor.
D)The high-affinity IL-2 receptor is assembled after T-cell activation.
E)Rapamycin is an immunosuppressive drug that inhibits signaling of IL-2 through the IL-2 receptor.

Question 29

Which of the following statements regarding leprosy is false?

A)It is caused by the bacterium Mycobacterium leprae.
B)Disease progression is influenced depending on whether the immune response is polarized toward either a T_H1 or T_H2 response.
C)The tuberculoid form of leprosy is associated with localized inflammation and granuloma formation.
D)In lepromatous leprosy,the patient makes a T_H2 response that clears the mycobacteria from the body.
E)The less severe form of leprosy presents with high levels of IL-2 and IFN-γ produced by responding T cells.

Question 30

of the following are included in the central supramolecular activation complex (c-SMAC)except _____.

A)CD4 or CD8
B)ICAM-1
C)CD28
D)T-cell receptor
E)PKC-θ.

Question 31

Which of the following is incorrect regarding sphingosine 1-phosphate (S1P)and its receptor?

A)It is a lipid that has chemotactic activity.
B)S1P gradients are established in lymph nodes with lowest concentrations in T-cell areas.
C)CD69 upregulates S1P receptor expression on the surface of naive T cells.
D)S1P is synthesized by all cells.

Question 32

Which of the following is not produced by T_H17 cells?

A)ICOS (inducible T-cell co-stimulator)
B)IL-17
C)CD4
D)IL-21
E)STAT3

Question 33

Identify the mismatched pair.

A) T_FH cells: Bcl6
B) T_H1: GATA3
C) T_H1 cells: IFN-\gamma
D) T_H2: IL-4
E) T_reg: TGF-\beta

Question 34

During cytokine signaling,_____ translocate(s)to the nucleus and direct(s)the upregulation of gene expression.

A)perforin
B)STATs
C)CD40 ligand
D)TGF-β
E)CXCL2.

Question 35

important way in which effector T cells differ from naive T cells is that _____.

A)the cell-surface level of LFA-1 is lower on effector T cells
B)L-selectin is upregulated during differentiation of effector T cells
C)cellular proliferation occurs after effector T cells leave the secondary lymphoid tissues
D)the provision of co-stimulatory signals is not required to induce a response by effector T cells
E)effector T cells do not recirculate between lymph,blood,and secondary lymphoid tissues.

Question 36

of the following statements refer to regulatory T cells except ____.

A)they produce anti-inflammatory cytokines
B)they express elevated levels of CD25
C)they express FoxP3
D)they enhance the production of new effector T cells
E)they suppress the function of existing T cells

Question 37

a person with lepromatous leprosy,the lesions would contain mRNA for _____.

A)lymphotoxin (LT)
B)IL-2
C)IL-5
D)IFN-γ
E)granulysin.

Question 38

Signal transducers and activators of transcription (STATs)are _____ that are phosphorylated by _____.

A)transcription factors; JAKs
B)protein kinases; other STATs
C)cytokine receptors; JAKs
D)cytokines; cytokine receptors
E)transcription factors; Lck.

Question 39

is induced in a CD4 T_H2 cell under the direction of the transcription factor _____.

A)T-bet
B)FoxP3
C)AP-1
D)GATA-3
E)NFAT.

Question 40

Tuberculoid leprosy is characterized by a _____-type response in which patients _____.

A)T_H2; usually survive
B)T_H2; eventually die
C)T_H1; usually survive
D)T_H1; eventually die
E)T_reg; eventually die.

Question 41

Clonal expansion and differentiation of naive T cells to effector T cells depends on the activation of the transcription factor(s)_____ through a ZAP-70-mediated signal transduction pathway.(Select all that apply.)

A)AP-1
B)IL-2
C)NFκB
D)NFAT
E)Ras.

Question 42

are the roles of the following molecules in the signal transduction pathway leading from the T-cell receptor: (i)the CD3 complex; (ii)protein tyrosine kinase Lck; (iii)CD45; (iv)ZAP-70; (v)the ζ chain; (vi)inositol trisphosphate (IP₃); (vii)calcineurin?

Question 43

Binding of _____ to _____ induces T-cell proliferation and differentiation of activated T cells.

A)CD4; MHC class II
B)CD28; B7
C)LFA-1; ICAM-1
D)IL-2; the high-affinity IL-2 receptor
E)IL-2; the low-affinity IL-2 receptor.

Question 44

cells failing to encounter specific antigen leave lymph nodes via the _________.

A)germinal center
B)bloodstream
C)high endothelial venules
D)afferent lymph
E)efferent lymph.

Question 45

Which of the following is a protein tyrosine kinase involved in T-cell activation culminating in T-cell proliferation and differentiation?

A)AP-1
B)ZAP-70
C)NFκB
D)NFAT
E)calcineurin.

Question 46

cytokine receptors are associated with cytoplasmic protein kinases called _____,which become activated when the cytokine receptors bind to their respective cytokines.

A)ZAP-70
B)STATs
C)Lck
D)ITAMS
E)JAKs.

Question 47

Fos,a component of the transcription factor AP-1,is activated during T-cell signaling by a process involving a GTP-binding protein called _____.

A)inositol trisphosphate
B)Ras
C)protein kinase C-θ
D)Lck
E)ZAP-70.

Question 48

etiological agent responsible for leprosy is Mycobacterium leprae,which survives and replicates within the vesicular system of macrophages.Explain the difference between tuberculoid leprosy and lepromatous leprosy in the context of T-cell differentiation and effector function.

Question 49

Parents who were distantly related to each other brought their 11-week-old infant Kristen to the emergency room after she had a seizure accompanied by a persistently high fever and running nose.Her liver and spleen were palpable (hepatosplenomegaly).Laboratory tests revealed abnormally high levels of lymphocytes,and of the cytokines IFNγ,TNF-α,and IL-6.Conversely,levels of hemoglobin and platelets were abnormally low.Bone marrow aspiration showed the presence of macrophages containing phagocytosed red blood cells and numerous large granular lymphocytes.Molecular analysis was carried out to confirm the physician's suspicion of a congenital immunodeficiency.A frameshift mutation in the perforin gene PRF1 was found on both chromosomes.Kristen was diagnosed with the rare,potentially life-threatening disease known as familial hemophagocytic lymphohistiocytosis (FHL).Cytotoxic and aggressive immunosuppressive chemotherapy was administered followed by a matched unrelated hematopoietic stem cell transplant.Two years later Kristen is a healthy toddler.Which of the following would not be consistent with the etiology of FHL?

A)impaired cytotoxic activity of CD8 T cells
B)inhibition of transcriptional activators required for IL-2 synthesis
C)inability to kill virus-infected cells
D)persistent activation of CD8 T cells causing secretion of large amounts of IFN-γ
E)IFN-γ activation of macrophages which in turn drives the production of IL-6,TNF-α,and other pro-inflammatory molecules.
ANSWERS

Question 50

Which of the following is a feature of regulatory T cells (T_reg)? (Select all that apply.)

A)T_reg express CD8 and control effector cells by inducing apoptosis.
B)T_reg express high levels of CD25 (IL-2 receptor α chain)and secrete pro-inflammatory cytokines such as IFN-γ.
C)Physical association between T_reg and their target cells is mandatory for T_reg function.
D)By interacting with dendritic cells in secondary lymphoid tissue,T_reg prevent the interaction and activation of naive T cells.
E)T_reg secrete TGF-β and suppress effector T-cell function.

Question 51

Virus-infected cells attacked and killed by effector cytotoxic T cells are often surrounded by healthy tissue,which is spared from destruction.
A.Explain the mechanism that ensures that cytotoxic T cells kill only the virus-infected cells (the target cells).
B.What cytotoxins do cytotoxic T cells produce?

Question 52

process by which cytotoxic T cells kill their targets involves _____.(Select all that apply.)

A)inducing the target cell to undergo necrosis
B)inducing apoptosis (programmed cell death)in the cytotoxic T cell
C)DNA fragmentation in lengths of multiples of 200 base pairs in the target cell
D)shedding of membrane-bound vesicles and shrinking of the target cell
E)release of granzyme,perforin,and granulysin by the cytotoxic T cell.

Question 53

Expression of IFN-γ is induced in a CD4 T_H1 cell under the direction of the transcription factor ______.

A)T-bet
B)FoxP3
C)AP-1
D)GATA-3
E)NFAT.

Question 54

the absence of a co-receptor (CD4 or CD8 for T helper cells or cytotoxic T cells,respectively),T cells require _____ specific peptide:MHC complexes on the antigen-presenting cell compared with interactions involving a co-receptor.

A)more
B)fewer
C)the same number of.

Question 55

Describe two distinct mechanisms by which naive CD8 T cells can be activated.

Question 56

Which of the following characteristics permits activated CD8 T cells to destroy any cell type harboring viable and replicating pathogens such as viruses?

A)The pathogen is located in extracellular spaces.
B)CD8 T cells enable macrophages to kill intracellular pathogens.
C)Pathogen-derived peptides bind MHC class I molecules in endocytic vesicles found ubiquitously in most cell types.
D)MHC class II molecules are expressed ubiquitously by most nucleated cells.
E)MHC class I molecules are expressed ubiquitously by most nucleated cells.

Question 57

_____ is a second messenger in the T-cell signaling pathway leading to the activation of NFAT.

A)diacylglycerol (DAG)
B)NFκB
C)inositol trisphosphate
D)Fos
E)Ras.