Chapter 6: T-cell-mediated immunity & effector mechanisms Flashcards
How was cell-mediated immunity discovered?
immunity transferred from one lab animal to a naïve animal only by cells (T-cells)
Phagocyte with ingested microbes in vesicles leads to…
macrophage activation
inflammation
- via T cells
Infected cell with microbes in cytoplasm leads to…
killing of infected cells via CD8+
What are the target cells of Th1?
macrophages
What are the target cells of Th2?
eosinophils
(B cells and macrophages)
What are the target cells of Th17?
neutrophils
What are the defenses for Th1?
intracellular pathogens
What are the defenses for Th2?
parasites (helminths)
What are the defenses for Th17?
extracellular pathogens
What is the role in disease for Th1?
autoimmunity
chronic inflammation
What is the role in disease for Th2?
allergy
What is the role in disease for Th17?
autoimmunity
What are the general properties of T cell cytokines?
- produced transiently in response to antigen
- acts on the same cell or nearby cells
- each cytokine has multiple biological actions
- redundancy
What are the cytokines of selected T cell cytokines?
IL-2
interferon-y
IL-4
IL-5
IL-17
IL-22
TGF-B
What is the signature cytokine of Th1 cell?
IFN-y
What is the result of the Th1 cell activation?
classical macrophage activation
- increased expression of MHC and costimulators
- secretion of cytokines
What allows for the Th1 cells to be formed?
- intracellular microbes plus either a dendrictic cell (IL-12) or NK cell (IFN-y)
What allows for the Th2 cells to be formed?
- helminths plus mast cell and eosinophil (IL-4)
What allows for the Th17 cells to be formed?
- extracellular, fungi, bacteria plus dendritic cell (IL-1, IL-6, IL-23, TGF-B)
What are the signature cytokines of TH2 cells?
IL-4, IL-5, IL-13
What does IL-5 from Th2 cells do?
eosinophil activation
What does IL-4 alone from Th2 cells do?
- antibody production via B cells
- mast cell degranulation
What does IL-4 and IL-13 form Th2 cells do?
- intestinal mcus secretion and peristalsis
- alternative macrophage activation
What allows for eosinophil granules to escapethe eosinophil?
IgE and IL-5
Th2 cytokines IL-4 & IL-13 inhibit…
classical macrophage activation
What does the alternative activated macrophage path via Th2 cells do?
antiinflammatory effects
Th1 cytokine IFNgamma inhibits…
Th2 and Th17
Vasoactive amines and lipid mediators from Th2 cells and mast cells leads to?
immediate hypersensitivity reaction
Cytokines from Th2 cells and mast cells leads to?
late-phase reaction
Balance between Th1 and Th2 cell activation determines outcome of…
intracellular infections
What is the major function of Th17 cells?
- Recruitment of neutrophils,
resulting in inflammation - antimicrobial peptides
- increased barrier integrity
What are the signature cytokines of Th17?
IL-17, IL-22
What travels through the synapse between the target cell and CD8+ cell?
perforin
granzymes
- activates apoptosis
Host counter defense to reduced MHC class I display on cell surfaces
activation of natural killer cells
