T cells lecture 2 Flashcards
What are 3 types of APCs that express both MCH-1 and MHC-II
Dendritic Cells
Activated macrophages
Activated B cells
Other cells that are not APCs and express MHC-I are known as?
Target cells
Virus infected
Malignant
Aging cells
Cells from graft
Why can’t we fight all viruses?
Virus are diverse
Evolve
Selection
What is the role of T cells in the immune system?
Immune response
Activate CD4 and CD8 against virus, bacteria and parasites
Activated in response to tumour cells
Cells from foreign grafts
How naive T cells activated against pathogens?
Dendritic cells take up pathogens and traffic to the lymph node
Lymph node- interact with T cells
Activate T helper cells and Killer T cells
T helper cell humoural and cell-mediated responses
APC
- peptide antigen on MHC class II
interacts with TCR of CD4 T cell
Differentiates in helper T cell and produce cytokines
Help CD8 - attack
B cell - secrete antibodies
T helper cell humoural and cell-mediated responses: cytokines produced
IL-2
IL-4
IFN
IL-2
IL-4
IFN
Priming and helping the B cell
Bacteria targeted by
CD4+ T cell
Activation of CD4+ release
Cytokines
Release of cytokines stimulate
Macrophages
CD8 T cell
D cells
Viral infected cells are killed by
CD8+ T cells
Two signal model of T cell
Co-stimulation
2 signal needed for T cell activation
- MHC and TCR
- B7.1/B7.2 and CD28 (found on T cell) `
B7.1/B7.2 is what type of molecule?
Co-stimulatory molecule
Always expressed APC
Clonal expansion
Many T cell with T cell receptor specific
For specific MHC/peptide complex
Co-stimulation and clonal expansion mechanism
- TCR and specific MHC peptide complex binding
- 2 signals- B7 (apc) CD28 (T cell)
- T cell produce IL-2 (triggers proliferation)
- several division -> population of memory and effector cell
CD8+T cell killing
CD8+T interact with APCs
Detect pathogen peptides on MHC molecules
T cell become activated-> differentiate into cytotoxic T cells
CD8+T weapons
Perforin
Granzymes
Grulysin
Perforin
Aids delivering contents of granules into the cytoplasm
Granzymes
Serine proteases
Initiate apoptosis once injected into cytoplasm
Granulysin
Antimicrobial
What do CD8+T cell release into the target cell?
Cytotoxic granules
T cell development un thymus: initially
Double negative
Don;t have CD4 / CD8 receptor
DN3
Double negative 3
Pre TCR
VDJ recombination (thymus)
Not mature
DN4
Prolifieration
Double-positive
CD4 and CD8 TCR
Single positive
CD4 TCR or CD8 TCR
Positive Selection
T cells
-TCR
-Recognise MHC and self peptide
-selected for survival
Negative selection
T cells that recognise MHC and self peptide too well are deleted
