4.14 Cooperation in the immune system Flashcards
1
Q
How do the levels of costimulator molecules in APC change?
A
- Dendritic cells ‘quiescent’ in normal tissue
- Low MHC-II, no (low) C80, no (low) CD86, low levels adhesion molecules, high pinocytosis rate
- Activated by PRR
- Migrate to LN, upregulate MHC-II, upregulate antigen processing and presentation, upregulate CD80, CD86, adhesion molecules
2
Q
What does the binding of PAMPs to dendritic cell pattern recognition receptor induce?
A
- Migration of DC to the lymphoid tissue via the lymphatics
- Increased antigen processing
- Increased surface expression of MHC I and II
- Increased surface expression of adhesion molecules
- Expression of co-stimulatory molecules (CD80, CD86)
- Secretion of cytokines (eg TGF-b, IL-6, IL-12)
3
Q
What are the three signals in the interaction between naive T cell and dendritic cell?
A
- Signal 1: TCR: peptide-MHC complex Results in activation of the T cell
- Signal 2: co-stimulatory molecules Stimulates IL2 production and Results in survival of the T cell
- Signal 3: cytokines, Induces differentiation of the T cell
4
Q
What autocrine factor is released in an activated T cell?
A
• IL2 autocrine factor
5
Q
How does signal 3 differentiate effector helper CD4+ T cells?
A
6
Q
What are the actions of CD4+ helper T cells?
A
- help B cells to produce antibody (occurs in LN)
- aid the production of cytotoxic T cells (occurs in LN)
- help the activation of macrophages (occurs in tissues)
- aid neutrophil recruitment (occurs in tissues)
7
Q
What happens to B cells without T cell help?
A
- No isotype switching : B cells secrete IgM
- Antibodies with poor binding affinity (prefer high affinity)
- No B cell memory
8
Q
What co-stimulators are seen in Helper T cells and B cells when CD4 T cells help B cells?
A
9
Q
What are the process of CD4+ T cell help for B cells?
A
10
Q
How do CD4 T cell provide help for macrophages?
A
11
Q
What is the effector function of CD8+ T cells?
A
- cytotoxic T cell recognise antigens from cytosolic compartments
- Displayed on MHC 1
- T cell receptor look for cell displaying MHC 1
- Release granules upon antigenic stimulation
- Performin assemble on membrane of target cell
- Granzymes induce cell death
