Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Infection and Immunity > T cell subsets and functions > Flashcards

T cell subsets and functions Flashcards

1
Q

How are naive CD8+ cells activated?

A

Recognise antigen or infected APC
Costimulators B7 and CD28 provide survival signal
APC release cytokines IFN-A, IFN-G and IL-12
Clonal expansion and differentiation of effector CTLs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What do CD8+ cells cause?

A

Lysis of target cells by either:
- releasing cytotoxic granules at site of contact with target cell
- engage Fas/FasL interaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Describe perforin-granzyme-mediated cell killing

A

CD8+ cell binds target cell and releases granule contents into immune synapse
Perforin induces uptake of granzymes into target cell endosome and release into the cytosol
Caspases become activated and target cell undergoes apoptosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Describe Fas/FasL mediated cell killing

A

FasL on CTL interacts with Fas on target cell
Apoptosis of target cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What cell types can up regulate MHC II during infection and be lysed by cytolytic CD4+ cells?

A

WNDV-infected MHC II positive epithelial cells
EBV-infected B cells
HIV-infected CD4+ cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How do CD4+ cells act as Th cells?

A

Activate and help other cell types to coordinate immune response
Achieved through expression of cell surface proteins and soluble cytokines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What causes acquired immune deficiency syndrome (AIDS)?

A

Results from loss of helper T cells following HIV infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the types of Th cells?

A

Th1
Th2
Th17
Tfh

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What cytokine is released by Th1 cells?

A

IFN-G

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the functions of Th1 cells in the adaptive immune response?

A

Activate infected macrophages
Provide help to B cells for Ab production

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What pathogens are targeted by Th1 cells?

A

Microbes that persist in macrophage vesicles
e.g. mycobacteria, Listeria, Leishmania donovani, Pneumocystis carinii
Extracellular bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What cytokines are released by Th2 cells?

A

IL-4
IL-5
IL-13

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the functions of Th2 in the adaptive immune response?

A

Provide help to B cells for Ab production, especially switching to IgE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What pathogens are targeted by Th2 cells?

A

Helminth parasites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What cytokines are released by Th17 cells?

A

IL-17
IL-22

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the functions of Th17 cells in the adaptive immune response?

A

Enhance neutrophil response
Promote barrier integrity (skin, intestine)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What pathogens are targeted by Th17 cells?

A

Klebsiella pneumoniae
Fungi (Candida albicans)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What cytokine is released by Tfh cells?

A

IL-21

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the functions of Tfh cells in the adaptive immune response?

A

B cell help
Isotype switching
Ab production

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What pathogens do Tfh cells target?

A

All types

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What determines the outcome of naive CD4+ Th cell differentiation?

A

Signals generated by DCs

22
Q

What DC signals cause differentiation of Th1 cells?

A

IL-12
IL-18
IFN

23
Q

What DC signals cause differentiation of Th2 cells?

A

IL-4
IL-5

24
Q

What DC signals cause differentiation of Th17 cells?

A

IL-6
TGF-B

25
Q

What DC signals cause differentiation of Tfh cells?

A

IL-6

26
Q

What DC signal causes differentiation of Treg cells?

A

TGF-B

27
Q

What do Th1 cells do?

A

Activate macrophages to kill bacteria within them

28
Q

How do Th1 cells activate macrophages?

A

Some infections hide in phagosomes e.g. mycobacteria - this protects them from MHC-I antigen presentation
Peptides from these bacteria will be presented by MHC-II as macrophages are professional APCs
Recognition of peptide/MHC-II on an infected macrophage causes Th1 cell to produce IFN-G
IFN-G activates the macrophage

29
Q

What happens once macrophages are activated?

A

Macrophage fuses phagosome containing bacteria with lysosomes
ROS and nitrogen species kill the bacteria

30
Q

Why can macrophages not be activated all the time to prevent infection?

A

Requires too much energy
Results in localised tissue destruction due to release of reactive species

31
Q

How can activation of CD8+ cells be CD4+ dependent?

A

Recruited CD4+ cells can induce secretion of chemokines from DC, leading to attraction of CD8+ cells

32
Q

How do Th1 cells help B cells in Ab production?

A

B cells process and present antigens that bind to their surface Ig
Binding of antigen by surface Ig causes receptor mediated endocytosis
Antigen is delivered to MHC-II for presentation
This stimulates helper T cells that recognise the same antigen as the B cells

33
Q

What does IFN-G production from Th1 cells stimulate?

A

Stimulated B cells to upregulate Ab production
Mainly IgG2a

34
Q

What do Tfh cells do?

A

Stimulate B cell proliferation and differentiation
Stimulate Ig class switching

35
Q

What are Tfh cells critically needed for?

A

Germinal centre formation and function

36
Q

What do Th2 cells do?

A

Help to control parasitic infection by promoting IgE production and by promoting function of eosinophils and mast cells

37
Q

How do eosinophils clear parasitic infections?

A

IgE connects eosinophils to outer surface of a parasitic worm
IgE-bound pathogens bind to high affinity FceRI and FceRII receptors found on surface of eosinophils and mast cells
Large cytoplasmic granules of eosinophils contain variety of proteases and toxic proteins that aggregate and kill larval intestinal parasites that the eosinophils are attached to

38
Q

How do mast cells clear parasitic infections?

A

Activated by IL-5 and coated by IgE
Mast cells degranulate and release histamine, serotonin and leukotriene at the site of infection
These can cause contractions of the smooth muscle cells of the intestinal walls as a physical mechanism for expelling the worms from the digestive tract

39
Q

What does IL-4 promote?

A

Promotes Ig gene class switching leading to IgE transcription

40
Q

How does IL-4 promote Ig class switching to IgE?

A

IL-4 binds to IL-4 receptor
Leads to recruitment and activation of tyrosine kinases JAK1, JAK3 and TYK1
These activate STAT6
Interaction of CD40L with CD40 allows for recruitment and activation of tumour necrosis factor receptor associated factors (TRAFs) and nuclear translocation of TFs NG-kB and AP1
Stimulation of IL-4R and CD40 promote enhancement of both Ce germ line transcripts

41
Q

How does Th1/Th2 balance determine the outcome of infection in leprosy?

A

If Th1 cells predominate (tuberculoid leprosy) then bacterial growth is controlled and minor damage occurs
If Th2 cells predominate (lepromatous leprosy) the bacteria grow abundantly and gross tissue damage occurs

42
Q

What do Th17 cells do?

A

Secrete IL-17
Help protect against extracellular bacteria and fungi by stimulating neutrophils
Over-represented in autoimmune diseases

43
Q

What happens when infection is cleared?

A

Majority of effector B and T cells die by neglect and enter apoptosis
Some remain as memory cells but this is not well understood
Both CD8+ and CD4+ populations can establish memory

44
Q

Describe memory T cells

A

They are relatively short-lived and therefore need to divide fairly frequently
Memory T cells are maintained by IL-7 and IL-15 with stimulation from self-antigens

45
Q

Why are CD8+ T memory cells longer lived than CD4+ memory?

A

CD4+ are inherently less proliferative than B cells and CD8+ T cells
The CD4+ memory population appears to decline following antigen clearance, while CD8+ memory population if established are typically stable

46
Q

What are the typed of memory T cells?

A

Tscm
Tcm
Tem
Teff
Trm

47
Q

Describe Tscm memory cells

A

Stem cells
2 populations
Commonly short lived
Half life 7 months
Rarer, long lived have a half life of 9 years

48
Q

Describe Tcm memory cells

A

Central memory
Circulate between the blood and secondary lymphoid organs

49
Q

Describe Trm cells

A

Tissue resident
Mainly CD8+ cells
Often quite long lived

50
Q

Describe Tem cells

A

Effector memory
Migrate from blood into non-lymphoid tissues

51
Q

Describe Teff cells

A

Effector cells

Infection and Immunity (33 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions