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Immunology > L14- CD4+ T helper cells > Flashcards

L14- CD4+ T helper cells Flashcards

1
Q

What are effector functions of CD4+ T helper cells?

A

Proliferation
Cytokines
B cell help
APC activation

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2
Q

How does T cell activation occur?

A

Signal 1- Recognition of MHCII molecule on APC/Bcell by the TCR provides a signal which initiates activation of T cells.

Signal 2- Interaction of co-stimulatory molecules on surface of B and T cells.

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3
Q

What types of T cells do naieve CD4+ T cells differentiate into?

A

Th1- Coordinate inflammatory immune responses to intracellular pathogens (bacteria, viruses)

Th2- Help B cells make antibodies required for immune responses to extracellular pathogens

Both promote the generation of more leukocytes

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4
Q

What cytokines do Th1 cells produce?

A

IL2
IFN gamma
TNF beta

GMCSF
IL3

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5
Q

What cytokines do Th2 cells produce?

A

IL4
IL5
IL13

GMCSF
IL3

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6
Q

What does IL2 do?

A

Proliferation of activated T cells, enhancement of NK and T cell activity

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7
Q

What does IFN gamma do?

A

Macrophage activation
Elevation of MHCI and MHCII expression
Enhances NK and CD8+ activity
Class switching to IgG2a

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8
Q

What does TNF alpha/beta do?

A

Macrophage activation

Killing of transformed cells

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9
Q

What does IL4 do?

A

B cell proliferation
Class switching to IgE
Suppresses Th0 to Th1 differentiation

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10
Q

What does IL5 do?

A

B cell proliferation

Class switching to IgA

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11
Q

What does IL13 do?

A

B cell proliferation

Class switching to IgE

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12
Q

What does IL3 do?

A

Haematopoiesis

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13
Q

What does GM-CSF do?

A

Haematopoiesis

Differentiation of monocytes to macrophages

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14
Q

What are the transcription factors controlling Th1 differentiation?

A

IFN gamma
IL12
——> Stat1+4 and T-bet

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15
Q

What are the transcription factors controlling Th2 differentiation?

A

IL4

——-> gata3, cMaf (master regulator), Stat6

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16
Q

What is the Th1 differentiation pathway?

A 
Type 1 pathogens (bacteria,virus)
Macrophage, Dendritic cells
IL12 released
NK cell stimulated
IFN gamma released
Conversion of STAT-1 to Tbet
Increased IL12
Conversion of STAT-4 to IFN gamma
Increased IL-19Ralpha causes Th1 cell to be produced
17
Q

What is the Th2 differentiation pathway?

A 
Type 2 pathogens (helminthes)
Macrophages, Dendritic cells
STAT-6 converted to GATA
Increased cMaf causes increased IL-4
Th2 cells produced
18
Q

What is the relationship between T-bet and Gata-3?

A

They both inhibit eachother

19
Q

What is Th17?

A

A proinflammatory CD4+ T cell

20
Q

What are the cytokines produced by Th17 and what do they do?

A

TNF-alpha= Inflammatory response, macrophage and fibroblast activation

IL-17A/F= Induces IL-6, TNF-alpha, chemokines

IL-22= innate immune responses against bacterial pathogens

IL-21= promotes B-cell and antibody responses, regulates activation and differentation of T cells, APC’s, NK cells

GM-CSF, CXCL8= Haematopoiesis, macrophage differentiation, neutrophil recruitment

21
Q

What does IL-17 do?

A

Produced by Th17, CD8+,NK and innate lymphoid cells
Receptor ubiquitously expressed in tissue so effects are wide ranging

IL17A=
• Pathogenic role in autoimmune/inflammatory disorders
• Specialised and essential function in host defence against extracellular bacteria and some fungi (esp mucosal surfaces)

22
Q

What is the non pathogenic Th17 differentiation pathway?

A

Naieve T cell
TGFbeta and IL6
Th17 produced (non pathogenic)

(can be induced by intra/extracellular pathogen)

23
Q

What is the pathogenic Th17 differentiation pathway?

A 
Naieve T cell
TGFbeta and IL6
IL-23 
RORgammaT T.F. produced which produces TGFbeta3
IL6 and IL1 produce pathogenic Th17
24
Q

What do follicular helper T cells do?

A

Form cognate interactions with naive B cells through linked recognition of antigen and traffic to B cell follicles where they promote the germinal centre response.

Cause isotype switching and affinity maturation

25
Q

What is the Tfh differentiation pathway?

A

TCR binds to dendritic cell
Releases IL-6
Causes STAT6 activation which activates BCL-6 transcriptional repressor
Signalling by IL-21

Immunology (17 decks)

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