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Host and Defense > T cell-mediated immunity > Flashcards

T cell-mediated immunity Flashcards

1
Q

what is the most common APCs?

A

dendritic cells
they must be activated
presentation occurs in secondary lymphoid

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2
Q

how are DCs targeted to lymph nodes?

A

by CCR7 binding to CCL19 and 21

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3
Q

how do DCs present antigen?

A

via MHC I and II

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4
Q

why is cross-presentation critical for CD8 T cell activation

A

so that cells that aren’t infected can still activate T cells by presenting intra celluar antigen

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5
Q

what are the two routes that a naive T cell can enter a draining lymph node?

A

in the blood

in the afferent lymph coming from an upstream lymph node

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6
Q

why is it important for naive T cells to be in circulation?

A

because it allows for a high probability of antigen contact

  • systemic antigen exposure
  • localize activation
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7
Q

what two cells make up the immune synapse?

A

T cells

DCs

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8
Q

what dictates if a T cell is activated by a DC?

A

the tightness of binding between the TCR and MHC

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9
Q

T cell activation requires three signals, what are they?

A

TCR
Co-stimulatory molecules
cytokines

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10
Q

why are the co-stimulatory molecules important?

A

they signal to the T cell to stay alive

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11
Q

B7 and CD28 are the co-stim signals, which is on the DC and T cell

A

B7 is on the activated DC

CD28 is on the T cell

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12
Q

what is required for T cell activation?

A

B7-CD28 bindings

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13
Q

why do the cytokines do to T cells?

A

propagation and differentiation

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14
Q

IL-2

A

propagation and differentiation of CD8 and all Th cells

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15
Q

the absence of a co-stimulatory interaction leads to what?

A

anergy

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16
Q

what are the 5 steps of T cell activation

A 
differentiation
clonal expansion
changes in surface protein expansion
migration to target tissues
effector functions
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17
Q

what is an important thing that occurs with T cell activation

A

up regulation of adhesion molecules

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18
Q

what cytokine drives clonal expansion

A

IL-2

autocrine signaling

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19
Q

how does IL-2 drive clonal expansion

A

T cells produce own IL-2, which causes and upregualtion of IL-2 receptor, which then induces proliferation

20
Q

what inhibits continued T cell activation and proliferation?

A

CTLA-4

21
Q

How does CTLA-4 inhibit T cells?

A

it is expressed on activated T cells

  • binds an APC after activation leads to T cell inhibition
  • B7 binds CTLA-5 twentyfold stronger than CD28
  • *remember T cells DO NOT die after function is performed
22
Q

what are the two ways to activate naive CD8 T cells?

A

by autocrine IL-2 or by another CD4 T cell producing IL-2

23
Q

is there a secondary signal needed for activated T cells to kill and infected cell?

A

NO

the process is very specific

24
Q

how to CD8 T cells kill the infected cells?

A

perforin and granzymes

-causes caspase-mediated apoptosis

25
Q

why is granzyme important?

A

activates apoptosis

26
Q

what is granulysin

A

has antimicrobial actions and can induce apoptosis

27
Q

Th1

A

cellular mediated

28
Q

Th2

A

humoral mediated (antibodies)

29
Q

differentiation of CD4 involves what?

A

cytokine induction
transcription factor
effector cytokines

30
Q

cytokines that induce Th1 and function

A

IL-12 and IFN-gamma

-activate macrophages

31
Q

cytokines that induce Th17 and function

A

IL-16
TGF-beta
IL-23
-enhance neutrophil response

32
Q

cytokines that induce Th2 and function

A

IL-4

-activate cellular and antibody response

33
Q

cytokines that induce Tfh and function

A

IL-6
IL-21
-activate B cells maturation of antibody response

34
Q

cytokines that induce T reg and function

A

TGF-beta

-suppress other effector T cells

35
Q

what cytokines do Th1 cells produce?

A

IFN-gamma
TNF-alpha
IL-2
-these help macrophages to suppress intracellular infections

36
Q

what cytokines do Th2 cells produce?

A

IL-4
TGF-beta
-help basophils, mast cells, eosinophils, and B cells respond to parasite infection

37
Q

Th1 cells activate macrophages to do what?

A 
express co-signaling ligands
kill intra-cellular pathogens
release cytokines and antimicrobials
present antigen
*promotes inflammation
38
Q

Th1 cells also form granulomas when pathogens cannot be cleared, what is a granuloma

A

compact aggregate of leukocytes that sequester a pathogen

  • chronic inflammation
  • infections and non-infectious agents
  • several types
  • pyogenic granulomas are NOT true granulomas
39
Q

how can Th1 cells kill infected cells?

A

via the Fas ligand

40
Q

Th1 cells promote what?

A

INFLAMMATION

41
Q

Th2 cells promote what?

A

tissue protection and repair

42
Q

how do Th2 cells promote tissue protection and repair?

A

respond to prolonged extracelluar infection

  • mast cell and eosinophils recruitment and activation
  • B cell activation
  • cytokine release
43
Q

Tfh cell activate B cells and do what?

A

induce class switching

44
Q

where to Tfh cells activate B cells?

A

in the lymph nodes

45
Q

what do T reg cells do?

A

suppress other T cells by interacting with the same APC

46
Q

why are T reg cells important?

A

prevent T cell activation in the lymph node

  • stops adaptive immune response
  • prevents auto immunity
  • TGF-beta differentiation
47
Q

Th17 cells do what?

A
  • go to mucosal surfaces to release cytokines which bring neutrophils to area, tissue repair, antimicrobial peptide production
  • Th17 and T reg cells are enriched in the gut

Host and Defense (26 decks)

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