Effector function and T cells Flashcards
(22 cards)
Identify the principle effector function of naive CD4+ T cells [3]
- activate macrophages
- activated B cells
- cause inflammation
What are the principal effector functions of CD8 T cells [2]
- kill infected cells
- kill tumour cells
What is HEV [2]
- high endothelial venules
- highway for B and T cells
I identify the events leading up to T cel interaction with dendritic cells [3]
- dendritic cell presenting antigens enter T cell xone
- T cell enter HEV
- dendritic cell checks to see if T cell has complimentary receptor
A dendtic cell does not match the with T cell so…
it moves onto the next T cell zone
When a T cell receptor is complimentary to the dendritic cell antigen… [4]
- bind and stay together
- proliferation of T cell
- T cell differentiation in effector cells
- T cell exits via cortical sinuses
Do CD4 or CD8 T cells have faster clonal expression
CD8 (50,000x)
CD4 (1000)
What is the difference between the linear model and the branched model for T cell development
- naive T cells must come effector T cells before then become memory/apoptotic cells
- branched suggests naive T cells can either become effector T cells or to memory T cells
Describe the process of naive T cells activation [4]
- T cell binds to APC through LFA
- further binding of T cell receptors causes LFA to undergo conformational change
- increases affinity of cells for each other
- leading to prolonged cell-cell contact
What are the 3 signals required for the activation of naive T cells [3]
- T cell receptor engagement
- co stimulation
- cytokines
What receptors are invovled in co stimulation for naive T cell
- B7-1 and B7-2 on APC
- CD28 on T cell
Why are the different cytokine that are able to activate naive T cell (IL-6,12,23,4)?
- leads to different types of T cell differentiation
- different T effector cells have different functions
What is the role of CTL-A?
How
- inhibits T cells
- bind to regulatory T cells
- and activated T cells
Describe how Th2, Th1 and Treg cells have in regulation [3]
- Treg cells release TGF-B which suppress the differentiation and proliferation of both Th1 and Th2 cells
- Th2 cells secrete IL-4 which inhibits the differentiation of Th1 cells, and the development of TH17 cells
-Th1 cells secrete IFN-y which inhibits the proliferation of Th2 cells and inhibits the differentiation of Th17 cells
What is the main function of Th1 cells? [2]
- secrete IFN-Y
- which further activates macrophages
What are the main roles of Th2 cells [4]
- activated CD4 cells
- secrete IL5: activates eosinophils
- Secrete IL4 and IL13: increases mucous production
-activated B cells to become plasma cells
Th17 cells secreter IL-17. Identify the functions of IL-17 [4]
- recruitment of leukocytes and tissue cells
- which produce chemokine and cytokines]- leading ton inflammation, neutrophil response
- increased production of antimicrobial peptides
Th17 cells secrete IL-22. Identify the functions of IL-22 [3]
- activate tissue cells
- to produce antimicrobial peptides
-increase barrier function
What are the 4 main steps of cytotoxic T lymphocyte killing of target cells
- antigen recognition/immune synapse formation
- granule exocytosis
- CTL detaches
- target cell dies
Describe the process of perforin/granzyme mediated killing [4]
- perforin induced uptake of granzymes in to target cell endosome
- granzyme released into cytosol
- granzyme activated caspases, - leads to apoptosis
Describe how cytotoxic CD8 T cells target and induce cell death [3]
- If mHC interaction is strong enough
- the T cell induces DNA fragmentation within the cell
- leads to apoptosis
Define the term immunological synapse [3]
- forms between effector T cells and targets
- directs release of effector molecules
- cells are close together so that when granules released they are directed towards target cell
