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PA2203- Final > Infection & Immunity > Flashcards

Infection & Immunity Flashcards

1
Q

How are microbes recognized (what do they have and what do they bind to)

A

PAMPS that bind to pattern recognition receptors (PRRs) that are found withing and on cell surfaces

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2
Q

What does the ligation of TLRs lead to

A

Ligation leads to production of immflamatory mediators such as cytokines, proliferation, activation and survival

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3
Q

What do cell surface vs endosomal TLRs primarily recognize

A

Cell surface= PAMPS found on the surface of microbes (bac, viruses, etc)

Endosomal- genomes of microbes that enter via endocytosis

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4
Q

What are the endosomal TLRs

A

3,7,8,9

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5
Q

What do TLR1/2, 3, 4 5, 7/8, 9 recognize

A 
1/2- petidoglycan, Zymosan
3- dsRNA
4- LPS
5- Flagellin
7/8- ssRNA
9- Unmethylated CpG DNA
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6
Q

Where are NOD like receptors found, what do they bind and what do they do

A

Cytosolic PRRs
-bind peptidoglycan and other bacteria products

-Immflamatory PRRs (cytokine prod)

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7
Q

Where are RIG-I-like receptors found an dwhat do they regognize

A

Cytosolic inflammaory PRR involved in recognition of RNA virus by innate immune system

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8
Q

What is the complement pathway typically used against

A

Can be used against all classes of extracellular microbes- especially bacteria

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9
Q

What are the 3 functins of the complement pathway

A
  1. MAC complex- pores in microbial membrane
  2. Inflamation/chemotaxis- anaphylatoxins (C3a, C5a) recruiting and activating neutrophils/monocytes
  3. Opsonization- C3b tags microbial surfaces making microbe easier to be found by phago
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10
Q

What occurs in the classical, lectin and alternative pathway

A

classical- C1q binds antigens or antibodies IgM, IgG

Lectin- Lectins binds to microbial mannose residues on microbes

Alternative- Spontaneous activation of C3 on microbe surface

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11
Q

What does lysozyme do and where is it found and what is it effective against

A

in extracellular secretions

-hydrolyzes peptidoglycan and thus effective against gram pos bacteria (breaks down wall)

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12
Q

What are defensins produced by, what do they act on and what do they do

A
  • produced by epithelial cells

- insert themselvees into the outer leaflets of bac cell membranes (causing breakage of membrane)

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13
Q

What are the cells that can do phagocytosis (4)

A

Macrophages, neutrophils, monocytes, DCs

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14
Q

What are the 2 phagocytic receptors and ligands

A

Complement recptor- C3b

FcyR- Fc region of IgG antibodies on microbe surface

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15
Q

What are the first responders to inf, what are they effective against and what do they do

A

Neutrophils
-Bact and fungi targeted by neutrophils

-perform phago and secretes extracellular traps (NETs)

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16
Q

What do antibodies primarily target

A

extracellular antigens

17
Q

How are antibodies activated

A

TCr binds MHC II + ag on B cell
CD40 (b cell) binds to CD40L (Th1/2)
Cytokines (signal 3)

18
Q

What do you need for isotype switching to mucosal IgA

A

Retinoic acid

19
Q

What 2 antibodies perform neutralization

A

IgG

IgA

20
Q

What occurs in neutralization

A

Antibody blocks binding to virus receptor or even fusion event

21
Q

What does sIgA do

A

Neutralizes pathogens on mucosal surfaces

22
Q

What antibody performs opsonization and how does it occur

A

IgG antibody binds to bacterium and binds to fc receptors on cell surface where it will be phagod

23
Q

What antibody performs Antibody dependent cell mediated cytotoxicity and how does it work

A

–igG
Antibody binds antigens on surface of target cell
-Fc receptors on NK cells recognize bound antibody and kill target cell

24
Q

What antibody targets parasites for removal and how

A
  • -IgE
  • IgE tags surface antigen and Fc region on eosinophil recognizes IgE and causes release of substances ( Cytokines, chemokine, leukotienes etc)
25
Q

What does activated Th17 produce and what does it do

A

produces IL17
-IL17 binds to epithelial cells and causes the epithelial cells to produce chemokine that recruit innate phagocytes (neutrophils and macrophages)

26
Q

How do exogenous antigens activate macrophages

A

Th1 recognizes its epitope loaded on a macrophages MHCII
-CD40L on Th1 binds CD40 on macrophage
and th1 produces IFNy which activates macrophage

27
Q

How do th1 cells increase macrophage antimicrobial activity (3)

A
  • accelerated lysosome to phagosome fusion
  • Increased prod of toxic O/N compounds
  • Upregulation of MHC 1/2
28
Q

What are interferons

A

cytokines with broad antimicrobial activities

can be produced by virally infected cells as a natural response

29
Q

What do Type 1 interferons stim

A

results in a series of cell signalling events culminating in the transcription of interferon stimulated genes (ISG)

30
Q

What do interferon stimulated genes do

A

induces antiviral state

blocks entry, degrades cellular mRNAs, arrests cell translation, blocks egress

31
Q

What are the 3 main functions of Type 1 interferons

A

InF B (with Il12) activates NK

  • Increased synthesis of + Assembly of MHC molecules
  • induce antiviral state (ISGs)
32
Q

How are cytosolic pathogens delt with

A

loaded on MHCI and activated CD8 CTLs which perform cytotoxic activity

33
Q

How do CTLs cause apoptosis of infected target cells (3)

A
  • release cytotoxic granules (performing/granzymes)
  • Death ligands upregulated
  • Cytokines (TNFa, INFy) released
34
Q

What is inhibitory signal for NK cells

A

MHCI molecule on surface

35
Q

What is antigenic variation

A

Avoid detection by altering antigens (ex. Step pneumonia)

36
Q

What is latency

A
  • viruses can enter into a non replicative state called latency in which microbe doesn’t cause disease and because there is no viral replication it is harder for immune system to find
37
Q

How does HIV-1 effect the immune system

A

preferentially infects CD4 t cells leading to cell death and undermines helper t cell function
-leads to more opportunistic inf and cancers

PA2203- Final (11 decks)

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