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microbiology & immunology > 2.5 > Flashcards

2.5 Flashcards

1
Q

T cells express ___ that recognize peptides displayed by MHC molecules

A

T cell receptor (TCR)

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2
Q

TCR on each T cell clone is specific for a ___

A

distinct peptide

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3
Q

which is the difference between the receptors of the innate and adaptive immunity?

a - both are clonal
b - the receptors of the innate immunity are clonal
c - the receptors of the adaptive immunity are clonal
d - the receptors of the adaptive immunity are not antigen specific
e - the receptors of the innate immunity are antigen specific

A

c - the receptors of the adaptive immunity are clonal

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4
Q

membrane-bound heterodimeric proteins are composed of alpha and beta chains with ___ and __ regions

A
  • variable
  • constant
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5
Q

the TCR binding site has variable domains of alpha chains for ___

A

MHC class I

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6
Q

the TCR binding site has variable domains of alpha and beta chains for ___

A

MHC class II

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7
Q

the TCR recognizes ___

A

processed antigen

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8
Q

how is the diversity of TCR generated?

A

recombination of V, D, J gene segments

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9
Q

____ of gene segments accounts for diversity of TCR gene loci

A

somatic recombination

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10
Q

recombination of TCR gene segments occurs through ___

A

random selection

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11
Q

recombination of TCR gene segments is mediated by _____ that brings two segments close together

A

lymphocyte-specific VDJ recombinase (RAG)

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12
Q

what is the 1st step of recombination of TCR gene segments

A

recombination of D & J segments

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13
Q

what is the 2nd step of recombination of TCR gene segments

A

recombination of V segments with fused D-J element

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14
Q

what is the 3rd step of recombination of TCR gene segments

A

recombination of C segments with fused V-D-J element

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15
Q

_____ diversity is limited

A

combinatiorial

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16
Q

____ diversity is unlimited

A

junctional

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17
Q

what are the ways that junctional diversity is generated

A
  • exonucleases
  • terminal deoxyribonucleotidyl transferase (TdT)
  • tremendous diversity
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18
Q

Pre-T cells express one chain of antigen receptor called ___

A

pre-TCR

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19
Q

what are the functions of pre-TCR

A
  • promotes cell SURVIVAL
  • triggers TCR alpha gene recombination
20
Q

immature T cells express ___ that promotes cell survival

A

complete TCR

21
Q

immature T cells also express ___ (besides TCR)

A

CD4 & CD8

22
Q

in maturation of thymocytes, there are cycles of ___ where cells that do not express functional receptors die

A

expression of antigen receptors

23
Q

selected T cells are ___

A

single positive

24
Q

weak recognition of ___ leads to selection of T cells

A

MHC + peptide

25
Q

what do both strong or no recognition of MHC + peptide lead to

A

death

26
Q

how does the appropriate amount of antigen recognition in the thymus impact T cells

A

allows T cells to be selected and migrate to the periphery

27
Q

how are T cells specific for an antigen selected in the thymus?

a - upon strong recognition of antigen in thymus, T cells get positively selected
b - upon strong recognition of antigen in thymus, T cells get negatively selected
c - upon weak recognition of antigen in thymus, T cells get negatively selected
d - upon week recognition of antigen in thymus, T cells undergo apoptosis
e - upon lack of recognition of antigen in thymus, T cells get positively selected

A

b - upon strong recognition of antigen in thymus, T cells get negatively selected

28
Q

___ circulate from LN to LN in search of their antigens

A

naive T cells

29
Q

what occurs after effector T cells have migrated to the antigen sites in tissues

A
  • reactivation
  • carry out their function
30
Q

antigen recognition involves ___ & ___

A
  • proliferation
  • differentiation
31
Q

antigen recognition (signal 1) ALONE induces ___

A

unresponsiveness

32
Q

engagement of ___ on APC by ___ on T cells provides signal 2 and induces ___

A
  • B7
  • CD28
  • proliferation
33
Q

IL-2 produced by T cells helps ____

A

clone proliferation

34
Q

what is critical for limiting / terminating immune responses

A

inhibitory receptors

35
Q

___ are induced in activated T cells

A

inhibitory receptors

36
Q

concomitant activation of CD4 T cells provides help to CD8 T cells via ____

A

IL-2 production

37
Q

antigen-specific T cell clones expand in response to ___ in order to provide ____

A
  • antigens
  • a large pool of effector cells to fight infection
38
Q

where do memory cells reside

A
  • lymphoid organs
  • mucosal & peripheral tissues
39
Q

____ proliferate and differentiate

A

naive T cells

40
Q

most ___ leave LN except for ___ which function to help B cells

A
  • effector T cells
  • Tfh
41
Q

what are the effector functions of CD4 helper T cells?

A
  • activate phagocytes via IFN gamma production and CD40-CD40L
  • activate B cells to produce Ig via cytokine production and CD40-CD40L
42
Q

what allows T cell movement

A

combo of adhesion molecules & chemokine receptors

43
Q

circulation of T cells is different depending on their activation state. What statement below describes circulation of T cells accurately:

a - naive T cells circulate to the tissues when there is an infection
b - naive T cells circulate to the bone marrow where they encounter their antigens
c - naive T cells circulate to LN to encounter their antigens
d - effector T cells circulate to LN to encounter their antigens
e - memory T cells remain in the LN where they are activated

A

c - naive T cells circulate to LN to encounter their antigens

44
Q

what signals are provided by Thelper cells to help macrophages and B cells?

a - CD40L & IL-2
b - CD28 & IL-2
c - CD40 & IL-2
d - DTLA4 & IL-2
e - CD40L & IFN gamma

A

e - CD40L & IFN gamma

45
Q

what is the difference between naive and effector T cells in a situation in which there is an infection?

a - only naive T cells circulate in the body
b - effector T cells live for years while naive T cells have a short life
c - naive T cells contract when they do not encounter antigen
d - effector T cells contract following clearance of pathogens
e - effector T cells and naive T cells have a short life

A

d - effector T cells contract following clearance of pathogens

46
Q

what the following terms:
1 - CD28
2 - CD 40L
3 - MHC - I
4 - MHC - II
5 - IL - 2

a - CD40 - APC
b - TCR CD4
c - TCR - CD8
d - B7 - APC
e - IL-2R-T cells

A

1 - d
2 - a
3 - c
4 - b
5 - e

47
Q

what is necessary for thymocytes to survive and mature in the thymus?

a - expression of CD4 & CD8
b - expression of IL-7R
c - expression of TCR
d - expression of pre-TCR
e - expression of pre-TCR & TCR

A

e - expression of pre-TCR & TCR

microbiology & immunology (23 decks)

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