Adaptive Immunity: T cell Responses Flashcards
Things that happen in the thymus
- T cells commit to the T-cell lineage
- T cells complete rearrangement of the TCR
- T cells become either ab or yd cells
- development of unconventional T-cells (NKT/MAIT)
Components of a TCR
- 2 chains
- V region
- C region
- hinge (H)
- transmembrane region
- cytoplasmic tail
- disulphide bond
CD4 T cell subpopulations
- Th1
- Th2
- Treg
- Th17
- Tfh
Purpose of Th1
- intacellular pathogens
- autoimmunity
Purpose of Th2
- extracellar parasites
- asthma and allergy
Purpose of Treg
- immune tolerance
- lymphocyte homeostasis
- regulation of the immune response
Role of Th17
- extracellular bacteria
- Fungi
- tissue inflammation
- autoimmunity
Purpose of Tfh
- CXCR5+
- help to B cells
How are Tregs developed in the periphery?
in the presence of retinoic acid and TGF-B
Mechanisms of Suppression by FoxP3+ Tregs
- Deprivation of Tcon
- Active killing of Tcon
- Production of regulatory cytokines
Cytotoxic effector molecules
- Perforin
- granzymes
- granulysin
- Fas ligand
What are the unconvential T cells and what are they restricted by?
NKT (CD1-restricted)
MAIT (MR1-restricted)
Characteristics of yd T cells
- limited TCR gene usage
- can recognise antigens directly
- recognise non-peptide antigen
- enriched in epithelial tissues
- express TLRs
- produce inflam cytokines
What do NKT cells respond to?
glycolipid antigens presented on CD1d molecules
Which cytokines do NKT cells secrete?
IL-2 IL-4 IL-10 IL-13 GM-CSF TNF IFNy
How do T cells enter the lymph nodes?
- rolling (selectins)
- activation (chemokines)
- adhesion (integrins)
- diapedesis (chemokines)
How do lymphocytes in the blood enter lymphoid tissue?
through the walls of high endothelial venules
Signals that prime naive T cells
- interaction between specific MHC: peptide complex on APC and TCR
- co-stim signals that promote survival and expansion (CD28+B7)
- additional signals that direct differentiation (cytokines)
What is the relationship between telomere length and antigen experienced
Gets shorter as more antigen experienced
Why are polyfunctional T cells better?
- a single cells is able to respond to antigen through multiple effector functions
- produce more cytokine per cell
Potential T cell immune correlates
- T cell phenotype
- T cell function
- T cell antigen specificity
- HLA restriction
- T cell receptor
