T Cell Effector Functions Flashcards

1
Q

When the t cell is activated what does it release in order to promote proliferation

A

Activated t cells release cytokine IL-2+ IL-2 receptor which allows for rapid proliferation of t cell

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2
Q

what 3 cytokine signals are important for CD8 t cell differentiation

A

IL-12
IL-2
Type 1 IFN

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3
Q

How do activated CD8 t cells kill

A

infected cells will produce antigens and load them on MCH1 on their surface (if epitope is found it will kill the cell)

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4
Q

what type of cells do CD8 t cells kill

A

Since CD8+ T-cells are activated by endogenous (cytosolic) antigens, they function to kill cells that already contain “threatening” antigens inside of them

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5
Q

what cytotoxic molecules do t cell release to kill (3)

A
  1. Perforin- forms pores in membrane that allow entry of granzymes
  2. Granszymes- Induce apoptosis
  3. Granulysin- disrupt membranes/induce apoptosis
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6
Q

How are killer t cells anchored to target cell

A

Integrins (on t cell) and ICAMS (on target cell)

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7
Q

What does granzymes and granulysin lead to

A

Activation of caspases which activate caspase DNase which causes DNA digestion + blebbing

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8
Q

what effector cytokines can killer t cells released when a t cell identifies associated epitope (2)

A

1) Interferon gamma- activation of macrophages + NK cells

2) TNFa- upregs death receptors

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9
Q

What is an ex of a death ligand released by activated killer t cells

A

Fas ligand

-bind to death receptors on target cells and induce apoptosis

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10
Q

When a death ligand binds to its receptor what is recruited

A

allows recruitment of the death induced signalling complex (DISC) which activates caspases that mediate apoptosis

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11
Q

why are death ligands important for immune homeostasis

A

required for control of the number of lymphocytes activated during an immune response leading to the contraction of ongoing response

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12
Q

What types of CD4 cells does cytokines TGFb, IL6, Both, IL12, IL4

A
TGFb- Treg
IL6- Tfh
Both- Th17
IL12- Th1
IL4- Th2
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13
Q

What 2 signals does cd4 cells need to perform its effector function

A

Th1 TCR binds MHC2 and antigen

Co stim

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14
Q

What cytokine makes TH1 t cells and what do the t cells produce

A

IL12

IFNy- activation of macrophages/NK/bcells

IL2- t proliferation

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15
Q

When Th1 binds to an affected macrophage what is done

A

enhances macrophage antimicrobial activity by

  • accelerated lysosome to phagosome fusion
  • increase prod of toxins
  • upreg of MHC for antigen presentation
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16
Q

IL2 released by Th1 has what effect

A

increases proliferative capacity of activated killer t cells (cd8)

17
Q

What cytokine makes Th2 cells and what effector molecules does it release/do

A

IL4

IL4,5,13
Activate b cells
activate esonophils

18
Q

3 signals needed to activate b cells

A
  1. MHC2 + antigen binding to CD4
  2. Costim of CD40L (on t)+CD40 (on b)
  3. Cytokins IL4,5
19
Q

What is the function of T cell cytokines when activating b cells

A

different cytokines will stim b cells to make different classes of antbodies

20
Q

Activated Th2 cells release IL4, 5 what do they do

A

IL4- basophil + NKT cell activation

IL5- eosinophils (chronic asthma, allergy)

21
Q

What cytokine activated Tregs and what is its function

A

TGFb

Secretes immunosuppressive cytokines such as IL12 and TGFb

22
Q

What cytokine actives Th17 and what does it secrete

A

activated by: TGFb, IL6

releases: IL-17

23
Q

What does IL17 (released by Th17) do?

A

induces epithelial/innate cells to release:

G-CSF- promotes granulocyte prod in bone marrow

IL8- recruites neutrophils

24
Q

what type of infection is Th17 important for

A

important against extracellular and fungal infections + autoimmune disorders

25
What is the function of Follicular helper t cells (Tfh)
Important for b cell activity, differentiation, survival in germinal centre
26
What costims and cytokines are needed to activate Tfh
ICOS-L Il6
27
What is cross presentation and what is important for
where exogenous antigens are put on MHC1 (instead of 2) effective against viruses that don’t infect APCs
28
how long does primary t cell response take (inactivated to activated)
7-14 days
29
how many t cells will die after antigens eliminated
95%