T Cell Subsets and Function Flashcards
1
Q
Describe T cell development
A
- stars in bone marrow
- thymocytes migrate to thymus
- TCR genes rearrange
- differentiates into CD4 or CD8
- undergo positive and negative selection to remove autoreactive T cells - migrate to periphery
2
Q
Describe T cell Activation
A
- naive Th and Tc activated in secondary lymphoid tissues by DC
- cross-presentation critical
- proliferate upon activation
- aided by IL-2 production
- activated T cells express higher affinity IL-2 receptor
3
Q
Describe IL-2 driving T cell proliferation
A
- clonal expansion of T cell with correct TCR
- cytokine can act on cell producing it - autocrine
- cell lineages differentiate into effector or memory cells
4
Q
Where are activated T cells held?
A
lymph nodes
5
Q
Describe CD8 T cells
A
- adhesion molecules change
- after activation: leave secondary lymphoid tissue and re-enters circulation
- alter homing receptors to target inflamed endothelium
- search for infected host cells by checking MHC class I presentation
- killing of host cells via apoptosis
- after proliferation, differentiation occurs
6
Q
Describe CD8+ killing of host cells via apoptosis induction
A
- release of molecules such as perforin, granzymes, granulysin
- or Fas-FasL receptor interaction
7
Q
What are the different forms of CD8+ differentations?
A
- helper T cells
- cytokine production dependent on signal III
8
Q
What are the different forms of Th cells?
A
- Th1
- Th2
- Th17
- Treg
- TFH
9
Q
Describe Th1 cells
A
- differentiation promoted by Signal 3 containing IL-12, IFN-ү
- transcription factors activated are STAT1, Tbet
- function is to secrete IFN-ү, IL-12, TNF-α
10
Q
Describe what Th1 secretions lead to
A
- activation of macrophages (CD40-CD40L interactions)
- class switching to IgG (opsonizing Abs)
- increased MHC class I and II expression
- promotes NK cell activity
11
Q
Describe the target of Th1 secretions
A
- activating macrophages to migrate
- killing infected macrophages
- increased MHC class I
- critical for intracellular infections such as viral diseases
12
Q
Describe Th2 cells
A
- differentiation promoted by Signal 3 containing IL-4
- transcription factors activated are STAT6 and Gata3
- secretes IL-4, 5 and 13
- correct responses can be critical
13
Q
Describe what Th2 secretion leads to
A
- B cell proliferation and antibody production
- antibody class switching to IgE (IL-4)
- mucus production
14
Q
Describe the target of Th2 secretions
A
- IgE class switching
- increased antibody production
- activated mast cell and Eosinophils
15
Q
Describe Th17 cells
A
- differentiation promoted by Signal 3 containing IL-23, IL-6, TGF-β
- transcription factor achieved is RORүT
- secretes IL-17, IL-21, IL-22
