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Microbiology > Chapter 6- Effector Mechanisms of T Cell-Mediated Immunity > Flashcards

Chapter 6- Effector Mechanisms of T Cell-Mediated Immunity Flashcards

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Biology 101 flashcards
1
Q

what happens to a phagocyte with ingested microbes in vesicles and what T cell is used

A

-macrophage activation -> killing of ingested microbes
- inflammation and killing of microbes
- CD4+

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2
Q

what happens to an infected cell with microbes in cytoplasm and what T cell is used

A

killing of infected cells
-CD8+

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3
Q

what is the defining cytokines, target cell, host defense and role in disease of Th1

A

-IFNgamma
-macrophages
- intracellular pathogens
- autoimmunity; chronic inflammation

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4
Q

what is the defining cytokines, target cell, host defense and role in disease of Th2

A

-IL-4, IL-5, IL-13
-eosinophils
-parasites
-allergy

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5
Q

what is the defining cytokines, target cell, host defense and role in disease of Th17

A
  • IL-17 and IL-22
    -neutrophils
  • extracellular pathogens
  • autoimmunity
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6
Q

what is pleiotropism meant by in properties of T cell cytokines

A

each cytokine has multiple biological actions

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7
Q

what is redundancy meant by in properties of T cell cytokines

A

multiple cytokines may share the same or similar biological activites

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8
Q

what is the function of Th1 cells

A

classical macrophage activation
- killing of phagocytosed bacteria through production of ROS, NO, and lysosomal enzymes
- secretion of cytokines (TNF, IL-1, IL-12, chemokines)
- increased expression of MHC and costimulators- B7 molecules

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9
Q

Describe Th1 cell development

A
  • intracellular microbes + dendritic cell and NK cell
  • NK cell uses IFN- gamma to act on antigen activated T cell
  • dendritic cell uses IL-12 to act on antigen activated T cell
  • this results in a Th1 cell
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10
Q

what are Th2 cells induced by

A

parasitic worm infections

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11
Q

what are the signature cytokines in parasitic worm infections

A

IL-4, IL-5 and IL-13

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12
Q

what are the functions of Th2 cells

A
  • antibody production
  • mast cell degranulation
  • intestinal mucus secretion and peristalsis
  • eosinophil activation
    -alternative macrophage activation (enhanced fibrosis and tissue repair
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13
Q

what mediates the killing of helminths

A

eosinophils

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14
Q

what does Th1 cytokine IFN-gamma do

A

inhibits Th2 and Th17 developmental possibilities

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15
Q

what do Th2 cytokines IL-4 and IL-13 do

A

inhibit macrophage activation (M1)

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16
Q

what happens when a classically activated macrophage is activated by Th1

A

-microbicidal actions: phagocytosis and killing of bacteria and fungi
- inflammation

17
Q

what happens when an alternatively activated macrophage is activated by Th2

A

antinflammatory effects, wound repair and fibrosis

18
Q

what are immediate hypersensitivity reactions initiated by and what does it stimulate

A

-initiated by introduction of an allergen which stimulates TH2 reactions and IgE production
- IgE binds to Fc receptors on mast cells and subsequent exposure to the allergen activates the mast cells to secrete the mediators that are responsible for the pathologic reactions of immediate hypersensitivity

19
Q

what does the balance between Th1 and Th2 cell activation determine

A

outcome of intracellular infections

20
Q

Describe Th2 cell development

A

-helminths+ dendritic cells and mast cells, eosinophils
- mast cells and eosinophils use IL-4 to act on antigen activated T cell to make Th2

21
Q

what are the signature cytokines in Th17 cells

A

IL-17 and IL-22

22
Q

what are the functions of Th17 cells

A
  • recruitment of neutrophils resulting in inflammation
  • antimicrobial peptides
  • increased barrier integrity
23
Q

describe the development of Th17 cells

A
  • extracellular fungi and bacteria + dendritic cell
  • dendritic cell uses IL-1, IL-6, IL-23, and TGF beta to act on the antigen activated T cell
  • Th17 cell
24
Q

describe the mechanism of killing of infected cells by CD8+ CTLs

A

-antigen recognition and binding of CTL to target cell
- CTL activation and granule exocytosis
- apoptosis of target cell

25
Q

what activates apoptosis in CD8+ CTLs

A

-perforin facilitates entry of granzymes into the cytosol
- granzymes activate apoptosis

26
Q

what is the host counter defense to reduced MHC class I display on cell surfaces

A

activation of natural killer cells

27
Q

how does mycobacteria evade CMI

A

inhibition of phagolysosome fusion

28
Q

how does Herpes simplex virus evade CMI

A

inhibition of antigen presentation

29
Q

how does cytomegalovirus evade CMI

A

inhibition of antigen presentation

30
Q

how does Epstein barr virus evade CMI

A

inhibition of antigen presentation
- inhibition of macrophage activation

31
Q

how does the pox virus evade CMI

A

block cytokine activation of effector cells

Microbiology (39 decks)

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