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OLD "MIC 660" > Quiz 4 > Flashcards

Quiz 4 Flashcards

1
Q

What are the 2 lineages of a T cell?

A
  1. alpha/beta
  2. delta/gamma
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2
Q

What do alpha/beta lineage T cells recognize?

A

antigen peptides presented on MHC

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3
Q

What do delta/gamma lineage T cells recognize?

A

lipid antigens on CD1d

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4
Q

Which lineage of T cells don’t require antigen processing?

A

delta/gamma

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5
Q

What are the 2 types of T cells?

A

helper T cells (CD4)
cytotoxic T cells (CD8)

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6
Q

CD4 T cells bind to HLA _____

A

II

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7
Q

CD8 T cells bind to HLA _____

A

I

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8
Q

Where do T cells develope?

A

thymus

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9
Q

Explain thymic atrophy

A

thymus shrinks after childhood because new T cells that come from bone marrow are not needed much once you are older

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10
Q

What do thymic epithelial cells do?

A

activating signal to commit to being a T cell

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11
Q

what do thymic macrophages do?

A

clean up T cells that didn’t survive recombination

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12
Q

what do thymic dendritic cells do?

A

present antigens to aid in selection process

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13
Q

What is the origin of a T cell?

A

hepatopoietic stem cell in bone marrow

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14
Q

What happens during the double negative stage?

A

Notch I signaling for T cell commitment and beta, gamma, and delta chain undergo VDJ recombination

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15
Q

What signal is the commitment step for T cells?

A

Notch I

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16
Q

_____________ is used as a surrogate TCR alpha chain to test to see if the beta chain will work after rearrangment

A

pre-T-alpha chain

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17
Q

What is used to lock in the Beta chain selection so it cant change?

A

allelic exclusion

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18
Q

What happens during the double positive stage?

A

alpha, gamma and delta chain recombination

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19
Q

Which chain undergoes rearrangement first?

A

beta

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20
Q

Beta chain selection occurs during what phase?

A

double negative

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21
Q

alpha chain selection occurs during what phase?

A

double positive

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22
Q

alpha chain undergoes _____ recombination

A

VJ

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23
Q

what indicates that the alpha chain has recombined correctly?

A

when the beta chain is lost during VJ recombination

24
Q

What does positive selection ensure?

A

ensures TCR can interact with MHC (MHC restriction)

25
What are the 3 possible outcomes of alpha-beta TCR positive selection?
1. death by neglect 2. positive selection 3. negative selection
26
What is death by neglect?
no recognition of peptide-MHC
27
What is positive selection?
low affinity for MHC-peptide complex causing T cell to proceed through development
28
What is negative selection?
tight affinity for MHC-peptide complex causing T cell to be killed
29
What stage does negative selection occur?
single-positive
30
When will CD4 or CD8 be decided?
moving from double positive to single positive (only CD4 OR CD8 is expressed)
31
What are the two theories of single-positive selection?
1. instructive model 2. kinetic model
32
What is the instructive model of single positive selection?
interaction between alpha-beta TCR on double positive thymocyte and interaction between MHC and APC
33
What is the kinetic signaling model of single positive selection?
strong signaling events can drive CD4 expression and weaker signaling events drive CD8
34
What is the goal of negative selection?
to remove T cells that express a TCR for self-antigens
35
What is treatment for mutated negative selection?
autoimmune regulator (AIRE)
36
What do autoimmune regulators (AIRE) do?
allows gene expression by TEC so tissue specific antigens not normally expressed by epithelial cells or thymus are available for processing and presentation by HLA I
37
When does peripheral tolerance occur?
negative selection
38
What is peripheral tolerance?
making sure there are no self reactive T cells that slipped through the cracks
39
Where does T cell priming (activation) occur?
secondary lymphatic tissue
40
What do CD8 T cells target?
infected cells
41
What do CD4 T cells do?
activates cells to promote neutralization and phagocytosis
42
What are the 3 antigen presenting cells?
1. dendritic 2. macrophages 3. B cells
43
What antigen presenting cells don't phagocytose but internalize antigens
B cells
44
When do immature dendritic cells become mature?
after they phagocytose infection and migrate to secondary lymph tissue
45
What does CCR7 do?
receptor for (CCL21) chemokines that attract DC
46
What is cross presentation in dendritic cells?
acquire extracellular antigens for presentation on MHC class I molecules (diverting antigen from the HLA II pathway)
47
Where do macrophages stay?
tissue (don't move much)
48
What are macrophages important for?
inflammation
49
What HLA do B cells use?
HLA II
50
____ cells activate ____ cells
B cells T cells
51
What are high endothelial venules (HEVs)?
blood vessels found in secondary lymph tissue used for lymphocyte trafficking
52
What signal does sphingosine-1-phosphate (S1P) send to T cells?
they should exit secondary lymph tissue to go to site of infection
53
What is the immunological synapse?
adhesion molecules help bring T cells to dendritic cells for antigen presenting
54
without _______ nothing can be activated
synapse
55
What 2 signals are required for activating naive T cells?
1. TCR binding to MHC-peptide complex 2. CD38 binding to B7
56
What does ITAM (immunoreceptor tyrosine-based activation) do for T cell activation?
docking site for protein kinases
57
What is the role of IL-2 in T cells?
activating T cells increases expression of IL-2 which drives colonal expansion and mitosis

OLD "MIC 660" (10 decks)

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