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immuno med wk 2 > Mechanisms of Host Defense > Flashcards

Mechanisms of Host Defense Flashcards

1
Q

what are the main two mediators of the innate immune system’s response to intracellular pathogens?

A

phagocytes and NK cells

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2
Q

DCs/MOs produce IL-X and IL-X that activates NK cells

A

IL-12 and IL-15

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3
Q

Innate immunity is mediated by NKs and MOs. What’s the relation?

A

They have a reciprocal amplifying effect using IL-12 and IFN-gamma

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4
Q

how long does the innate system operate until the adaptive system kicks in?

A

7 days

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5
Q

What happens if there is no subsequent adaptive response to an infection?

A

infection will not be destroyed

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6
Q

How CTLs kill infected cells

A

1) granule exocytosis
2) entry of granzymes
3) activation of caspaces
4) apoptosis of cell

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7
Q

Edogenous pathway

A

intracellularly PRODUCED peptides like viral proteins are degraded in cytoplasm by proteosome; these pieces are shunted into the ER through TAP proteins.

there they are loaded into MHC class I molecules and delivered to the surface

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8
Q

Exogenous pathway

A

extracellular pathogens are engulfed by phagosomes; inside phagosomes the peptides are loaded into MHC II molecules and delivered to surface

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9
Q

M. Tuberculosis

A

survive by preventing lysosomes from fusing with phagosomes

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10
Q

3 methods intracellular pathogens utilize to evade immune system

A

1) prevention of lysosome and phagosome fusing
2) suppression of oxidative enzymes and nitrogen species
3) disruption of phagosome membrane, escape into cytoplasm

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11
Q

Defenses against Viruses

A

Antibodies
Cytotoxic lymphocytes
Type I interferon (alpha/beta)
NK cells

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12
Q

How do IFN-alpha/beta prevent host infection?

A

IFN-alpha/beta initiate intracellular aniviral processes PKR16: 2’, 5’ oligoadenylate synthetase: RNase L18 produces antiviral stae

express molecules that enhance susceptibility to CTL mediated killing of class I MHC

so an ANTIVIRAL state of the cell and CTL mediated killing of the cell

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13
Q

cytotoxic mechanisms of NK cells

2 response types

A

Inhibitory receptor engaged: no killing

inhibitory receptor not engaged: killing

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14
Q

ADCC

A

IgG binds to FcyIIIR recepor on NK cell and releases mediators causing apoptosis

so Ab has to bind to infected cell, and NK binds to Ab

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15
Q

Viral strategies of evading immune detection

antigen variation

examples

A

HIV, rhinovirus, influenze

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16
Q

Viral strategies of evading immune detection

Inhibition of antigen processing

examples

A

Herpes simplex blocks TAP transporter in MHC 1

Cytomegalovirus removes MHC I from ER altogether

17
Q

Viral strategies of evading immune detection

production of immunosuppressive cytokines

example

A

Epstein barr virus produces IL-10 lolololol

18
Q

Viral strategies of evading immune detection

infection of immunocompetent cells

HIV

A

HIV

19
Q

Main mechanisms against parasites

A

Mast cells, basophils, Eosinophils, Phagocytes, antibodies

20
Q

TH2 cells activate a number of different cell types against parasites: what are they and what are the cytokines involved?

A

Eosinophil activation involves IL-4 and IL-5
B cell IgE production (which activates mast/basophils is stimulated by IL-4 and IL-6
MO activation stimulation

21
Q

FcER1

A

mast cell receptor for IgE: multivalent cross links of IgE antibodies causes degranulation of preformed granules (histamine etc)

22
Q

Fungi are detected by what PRRs?

A

TLRs and C-lectin-like receptors

23
Q

b-glucan is detected by _____ on ____

A

dectin-1 on fungi

24
Q

What are the main cytokines involved in fungal infection, what do they do and who releases them

A

IL-12: activation of T cells –> activation of MO

IL-17+IL-23–> Neutrophil and epithelia activation for enhanced antifungal response

25
Q

What is Th2’s role in a fungal response?

A

It has none. Th2 involvement (Ab mediated) usually leads to further susceptibility of infection

26
Q

what is Th1’s role in fungal response?

A

Th1 is absolutely critical for fungal for its clearance

27
Q

Dectin-1

A

PRR for b-glucans on MOs (ONLY MOs)

b-glucans are mainly composed of glucose
dectin-1 is the main PRR against this epitope
signals NFkB signaling

immuno med wk 2 (27 decks)

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