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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
Q

What are the 3 possible outcomes of alpha-beta TCR positive selection?

A
  1. death by neglect
  2. positive selection
  3. negative selection
26
Q

What is death by neglect?

A

no recognition of peptide-MHC

27
Q

What is positive selection?

A

low affinity for MHC-peptide complex causing T cell to proceed through development

28
Q

What is negative selection?

A

tight affinity for MHC-peptide complex causing T cell to be killed

29
Q

What stage does negative selection occur?

A

single-positive

30
Q

When will CD4 or CD8 be decided?

A

moving from double positive to single positive (only CD4 OR CD8 is expressed)

31
Q

What are the two theories of single-positive selection?

A
  1. instructive model
  2. kinetic model
32
Q

What is the instructive model of single positive selection?

A

interaction between alpha-beta TCR on double positive thymocyte and interaction between MHC and APC

33
Q

What is the kinetic signaling model of single positive selection?

A

strong signaling events can drive CD4 expression and weaker signaling events drive CD8

34
Q

What is the goal of negative selection?

A

to remove T cells that express a TCR for self-antigens

35
Q

What is treatment for mutated negative selection?

A

autoimmune regulator (AIRE)

36
Q

What do autoimmune regulators (AIRE) do?

A

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
Q

When does peripheral tolerance occur?

A

negative selection

38
Q

What is peripheral tolerance?

A

making sure there are no self reactive T cells that slipped through the cracks

39
Q

Where does T cell priming (activation) occur?

A

secondary lymphatic tissue

40
Q

What do CD8 T cells target?

A

infected cells

41
Q

What do CD4 T cells do?

A

activates cells to promote neutralization and phagocytosis

42
Q

What are the 3 antigen presenting cells?

A
  1. dendritic
  2. macrophages
  3. B cells
43
Q

What antigen presenting cells don’t phagocytose but internalize antigens

A

B cells

44
Q

When do immature dendritic cells become mature?

A

after they phagocytose infection and migrate to secondary lymph tissue

45
Q

What does CCR7 do?

A

receptor for (CCL21) chemokines that attract DC

46
Q

What is cross presentation in dendritic cells?

A

acquire extracellular antigens for presentation on MHC class I molecules (diverting antigen from the HLA II pathway)

47
Q

Where do macrophages stay?

A

tissue (don’t move much)

48
Q

What are macrophages important for?

A

inflammation

49
Q

What HLA do B cells use?

A

HLA II

50
Q

____ cells activate ____ cells

A

B cells
T cells

51
Q

What are high endothelial venules (HEVs)?

A

blood vessels found in secondary lymph tissue used for lymphocyte trafficking

52
Q

What signal does sphingosine-1-phosphate (S1P) send to T cells?

A

they should exit secondary lymph tissue to go to site of infection

53
Q

What is the immunological synapse?

A

adhesion molecules help bring T cells to dendritic cells for antigen presenting

54
Q

without _______ nothing can be activated

A

synapse

55
Q

What 2 signals are required for activating naive T cells?

A
  1. TCR binding to MHC-peptide complex
  2. CD38 binding to B7
56
Q

What does ITAM (immunoreceptor tyrosine-based activation) do for T cell activation?

A

docking site for protein kinases

57
Q

What is the role of IL-2 in T cells?

A

activating T cells increases expression of IL-2 which drives colonal expansion and mitosis

OLD "MIC 660" (10 decks)

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