Lecture 3 Flashcards
Killing mechanism by NK cells
1)
2)
3)
1) Bind to target cell
2) Release granzymes, granulysin, perforins
3) Host cell, bacteria killed
Role of granulysin
Kill bacteria within host cell
Role of granzymes
Target cell undergoes apoptosis
CD8 killing of target cell 1) 2) 3) 4)
1) CD8 TCR binds to antigen presented on MHCI
2) Tc releases granzymes, granulysin, perforins
3) Perforins form holes in target cell membrane
4) Granulysins and granzyme enters target cell. Granulysins kill bacteria, granzyme makes target cell undergo apoptosis
Roles of antibodies 1) 2) 3) 4)
1) Opsonin
2) Neutralise toxins
3) Prevent adhesion to host-cell structures
4) Activate complement proteins
Which antibodies are good at activating classical complement pathway?
IgG1, IgG3
Which antibodies can activate alternative pathway?
IgM
Which antibodies have a J chain?
Dimeric IgA, pentameric IgM
What are two important binding sites on the Fc region of antibodies?
1) Complement-binding region
2) Phagocyte receptor-binding region
Pathways of antigen presentation
1)
2)
3)
1) MHC I
2) MHC II
3) CD1
MCH I pathway of antigen presentation
1) Cytosolic protein is degraded in proteosome
2) Antigenic protein is brought into ER by TAP (transport associated protein)
3) Antigen associates with MHC I
4) MHC I-antigen complex brought to cell surface
MHC II pathway of antigen presentation
1) Extracellular antigen is phagocytosed
2) MHC II leaves endosome in a vesicle, invariant chain dissociates from MHC II
3) Endosome containing antigen fuses with endosome containing MHC II
4) Antigen and MHC II complex
5) MHC II-antigen complex brought to cell surface
MHC I coreceptor
CD8
MHC II coreceptor
CD4
CD1 pathway of antigen presentation
1) Mannose receptor and CD14 bind lipid antigen
2) In early endosome, lipid antigen binds CD1
3) CD1 displayed on surface of cell
CD1 coreceptor
CD3 (displayed on some CD4 and CD8 T cells)
Main function of Th1
Control viral and intracellular bacteria
Main function of Th2
Control extracellular bacteria, metazoan infections
Cytokines for Th1 bias
IFNg
Which Th type does IFNg bias towards?
Th1
Cytokines for Th2 bias
IL-4
Which Th type does Th4 bias towards?
Th2
Cytokines for Th17 bias
TGFb
IL-6
IL-21
IL-23
Which Th type do TGFb, IL-6, IL-21 and IL-23 bias towards?
Th17
Cytokines for Treg bias
TGFb
Which Th type does TGFb bias towards?
1) Only TGFb –> Treg
2) TGFb with IL-6, IL-21, IL-23 –> Th17
Which factors are secreted by Th1?
TNFa
IFNg
IL-2
Which Th cell secretes TNFa, IFNg and IL-2?
Th1
Which factors are secreted by Th2?
IL-4
IL-5
IL-10
IL-13
Which Th secretes IL-4, IL-5, IL-10, IL-13?
Th2
Which factors are secreted by Th17?
IL-6
IL-17
TNFa
Which Th secretes IL-6, IL-17, TNFa?
Th17
Which factors are secreted by Treg?
TGFb
IL-10
Which Th secretes TGFb, IL-10?
Treg
Function of IFNg
1)
2)
1) Macrophage activation
2) Tc activation
TNFa function
1)
2)
1) Tc activation
2) Inflammation
IL-4 function
Antibody synthesis (IgG1, IgE)
IL-5 function
Eosinophil activation
Which interleukin activates eosinophils?
IL-5
Which interleukin promotes synthesis of IgG1 and IgE?
IL-4
IL-10 function
Downregulate immune response
IL-13 function
Downregulate immune response
Which interleukins downregulate the immune response?
IL-10. IL-13, TGFb
Which interleukins are responsible for inflammation?
IL-6
IL-17
TNFa
Function of IL-17
Recruit neutrophils
This leads to inflammation
Costimulatory molecules required for B cell activation
CD28 on T cell
CD 80, CD86 on B cell
Can B cells be stimulated independently of T cells?
Yes
With repeating epitopes (EG: nucleic acids, polysaccharides)
Antibodies produced with T cell independent B cell activation
IgG2, IgM
Antibody types that can use pIgR
IgA, IgM
IL-6 function
Promote liver to release acute phase proteins
Factors released by macrophages 1) 2) 3) 4) 5)
1) IL-1
2) IL-6
3) IL-8
4) IL-12
5) TNFa
Effect of IL-12 on NK cells
Increases NK release of IFNg
Effect of IFNg on Th1
Stimulates Th1 to stimulate B cells
