2. Effector Mechanisms of T Cell Mediated Immunity Flashcards
What are the general functions of a Th1 Cell?
Activation of cell mediated response to intracellular pathogens
Activates macrophages with IFN-γ
Promotes tumor immunity
Drives autoimmunity :(
In the Fas-FasL mediated apoptotic pathway, what is the function of Caspase 3?
Activates CAD by degrading its inhibitor (ICAD)
This causes DNA degradation and apoptosis
What is the role in CD40 on dendritic cells in educating / licensing CD8 T Cells?
CD40 interacts with CD40L on CD4 T Cells, which then secrete IL-2 and IL-21 to assist in the activation of CD8 T Cells.
Simultaneously the dendritic cell, due to CD40 interaction, secretes IL-12 to assist in T Cell activation as well.
CD40 also upregulates B7 (CD80/CD86) production and stimulates cross presentation
slide 29/30
How do Th1 cells amplify their own response as they’re being activated?
They secrete IFN-γ, which inhibits the development of Th2 and Th17 cells.
What is the defining cytokine for Th1 Cells?
IFN-γ
pg 133
What granzyme has been shown to be required for CTL cytotoxicity in vivo?
What is its direct action?
Granzyme B
Activation of caspase-3
What is the general function of a Tfh (Follicular Helper T) Cell?
They remain in the lymph nodes and help B Cells
What is the general function of a Th17 Cell?
Involved in inflammation and anti-bacterial response (extracellular bactera)
Recruits neutrophils and monocytes.
Possible tumor immunity?
Breaks immune tolerance :(
Autoimmunity :( (due to the above)
What cells secrete the cytokine that triggers differentiation into Th2 cells?
What cytokine are they producing to do that?
Mast cells and Eosinophils
IL-4
What transcription factor is involved in CTL (CD8+ T Cell) differentiation?
T-bet
How do Th2 cells amplify their own response as they are activated?
Production of IL-4 inhibits development of Th1 and Th17 cells.
What is the mechanism of immune evasion for:
Herpes Simplex Virus (HSV)?
Inhibition of antigen presentation by interfering with TAP
What transcription factors trigger differentiation into Th17 cells?
RORγt
STAT3
What do alternatively activated macrophages do?
Tissue repair
In the Fas-FasL mediated apoptotic pathway for Type II Cells, how do we get from Caspase 8 to Caspase 3?
Caspase-8 cleaves BID, which stimulates Cytochrome C.
Cytochrome C, Apaf-1, and ATP all work together to activate Caspase 9, which then activates Caspase 3.
What are the inducing cytokines for Treg cells?
IL-2
TGF-β
What are the inducing cytokines for Th17 cells?
TGF-β
IL-1
IL-6
What cytokine is produced by macrophages to activate Th17 cells?
IL-23
What are the defining cytokines for Th2 cells?
IL-4
IL-5
IL-13
pg 133
In the Fas-FasL mediated apoptotic pathway, what happens in Type 1 cells once Caspase 8 is created?
Caspase 8 directly cleaves caspase-3
What are the inducing cytokines for Th1 Cells?
IL-12
What two cytokines are produced by Th2 Cells to activate macrophages through the alternative macrophage activation pathway?
IL-4
IL-13
How does TGF-β promote Th17 responses?
Supresses Th1 and Th2
(Th1 and Th2 supress Th17 differentiation)
What is the mechanism of immune evasion for:
Pox virus?
Produces soluble cytokine receptors (basically antibodies) that bind up IL-1 and IFN-γ, inhibiting effector cell activation.
What is the mechanism of immune evasion for:
Epstein-Barr Virus (EBV)
Inhibition of antigen presentation by interfering with the proteosome so that antigens cannot be packaged.
Produces anti-inflammatory cytokine IL-10 to inhibit macrophage and dendritic cell activation.
What is the mechanism of immune evasion for:
Cytomegalovirus?
Inhibition of antigen presentation by two methods:
Interferes with proteosome so antigens can’t be packaged
Removes class 1 MHC from the ER, so it can’t be packaged upon
What are the inducing cytokines for Th2 cells?
IL-4
Where is the gene for CD40L located?
On the X Chromosome
In the Fas-FasL mediated apoptotic pathway, what is the fist step toward apoptosis?
Procaspase-8 is altered by the FADD adapter to become Caspase 8
What cytokine is involved in autocrine stimulation of Th17 cells?
IL-21
What is the general function of a Th2 Cell?
Activation of antibody mediated response to extracellular pathogens
Allergy :(
Athsma :(
What transcription factors trigger differentiation into Th2 cells?
GATA-3
STAT6
What transcription factors trigger differentiation into Th1 Cells?
T-bet
Stat4
Stat1
What is the function of IL-17?
Protects from extracellular pathogens
Involved in tissue inflammation
Autoimmunity :(
What is the mechanism of immune evasion for:
Mycobacteria?
They interfere with the fusion of the phagolysosome, and survive in the phagosome.
What is the defining cytokine for Th17 Cells?
IL-17 (thus the name)
IL-22
pg 133
Macrophages produce CD40 constitutively. What cell produces the ligand for CD40 (CD40L) when it is activated?
Th1 cells
