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Micro > Maturation and Activation of T cells > Flashcards

Maturation and Activation of T cells Flashcards

1
Q

what is RAG

A

recombination activating gene

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2
Q

severe combined immune deficiency (SCID) patients have a mutation in what

A

RAG1 and RAG2

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3
Q

what is TCR

A

T cell receptor

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4
Q

what do TCRs recognize

A

peptides displayed by MHC molecules

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5
Q

T/F TCR on each T cell clone is able to bind many peptides

A

False. TCR on each T cell clone is specific for a distinct peptide

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6
Q

what makes up the immune repertoire?

A

collection of distinct clones

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7
Q

describe the structure of TCR

A

membrane-bound heterodimeric protein composed of an alpha chain and a beta chain
there is a variable region and a constant region

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8
Q

where is the binding site for MHC I molecules

A

variable domain of alpha chains

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9
Q

where is the binding site for MHC II molecules

A

variable domains of alpha and beta chains

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10
Q

what is recognized by the TCR

A

1-3 residues of the peptides (processed antigen recognized)

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11
Q

what accounts for the diversity?

A

somatic recombination of gene segments

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12
Q

within the chains, what does V, D, J, and C stand for

A

variable
diversity
joining
constant

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13
Q

what does the TCR beta chain contain

A

variable, short diversity, joining and constant gene segments

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14
Q

what does the TCR alpha chain contain

A

variable, joining and constant gene segments. No short diversity

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15
Q

where are the D and J gene segments located

A

between V and C gene segments

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16
Q

during recombination are the segments selected precisely or randomly

A

random

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17
Q

what is the recombination mediated by

A

lymphocyte-specific VDJ recombinase (RAG) that brings two segments close together

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18
Q

what are the 3 steps in recombination

A
  1. recombination of D and J segments
  2. recombination of V segments with fused D-J element
  3. recombination of C segment with fused V-D-J element
    note: no D segment in alpha chain
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19
Q

what else leads to the increasing diversity

A

exonucleases - remove nucleotides
terminal deoxyribonucleotidyl transferase (TdT) - transfers nucleotides

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20
Q

where do T cells mature

A

thymus

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21
Q

how can a Pro-T cell be described and what does that mean

A

double negative
means CD4- and CD8-

22
Q

what promotes cell survival in maturing T cells

A

pre-TCR and complete TCR

23
Q

how can an immature T cell be described as what does that mean

A

double positive
means CD4+ and CD8+

24
Q

T/F maturing T cells that do not express functional receptors will die

A

True. Pre-TCR and TCR are both needed for survival

25
Q

what kind of recognition of MHC+ peptide leads to positive selection

A

weak recognition

26
Q

what kind of recognition of MHC+ peptide leads to cell death

A

no recognition and strong recognition

27
Q

weak recognition of class II MHC + peptide leads to what kind of cell

A

mature CD4+ cell

28
Q

weak recognition of class I MHC + peptide leads to what kind of cell

A

mature CD8+ cell

29
Q

T/F the appropriate amount of antigen recognition in the thymus allows T cells to be selected and migrate to the periphery

A

True

30
Q

where do naive T cells circulate in search of antigens

A

from lymph node to lymph node

31
Q

what occurs after antigen recognition to a naive T cell

A

proliferation and differentiation

32
Q

After effector T cells migrate to antigen sites in tissues they get:

A

reactivated and carry their function
(to keep cells @ site of infection)

33
Q

T/F antigen recognition (signal 1) alone is sufficient

A

False. antigen recognition (signal 1) alone induces unresponsiveness

34
Q

what provides signal 2 to induce proliferation of T cells

A

engagement of B7 (present on surface of APC) by CD28 (present on surface of T cells)

35
Q

what is produced by T cells to help clones proliferate

A

IL-2

36
Q

what are the three inhibitory signals and their receptors

A

B7-2 binds to CTLA-4
PD-L1 and PDL-2 bind to PD-1

37
Q

why are the inhibitory receptors important

A

critical for limiting/terminating immune response

38
Q

how does activation of CD4 T cells provide help to CD8 T cells

A

IL-2 production. IL-2 produced by CD4 helper T cell

39
Q

T/F antigen-specific T cell clones expand in response to antigen to provide large pool of effector cells to fight infection

A

True

40
Q

which t cells increase in number the most

A

CD8 cells

41
Q

where do memory cells reside

A

lymphoid organs and mucosal and peripheral tissues

42
Q

T/F most effector T cells do not leave LN

A

False. Most leave the lymph node

43
Q

which T cells do not leave the LN

A

follicular helper T cells (Tfh) - they help B cells

44
Q

what is the function of CD4 helper T cells in cell-mediated immunity

A

activate phagocytes via IFNy production and CD40-CD40L

45
Q

where is CD40 present

A

on macrophage and/or B cell

46
Q

where is CD40L present

A

on CD4+ T cell

47
Q

what is the function of CD4 helper T cells in humoral imunity

A

activate B cells to produce Ig via cytokine production and CD40-CD40L

48
Q

what allows for T cell movement

A

combination of adhesion molecules and chemokine receptor

49
Q

what is S1P

A

sphingosine 1-phosphate

50
Q

how do T cells exit LN

A

upregulate S1PR1 and follow S1P gradient
(downregulate S1PR1 to stay in LN)

Micro (15 decks)

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