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Medical Micro > lec 10-11 innate/adaptive immune response > Flashcards

lec 10-11 innate/adaptive immune response Flashcards

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USMLE® Step 1 flashcards
1
Q

innate immune response

A

non-specific
immediate
no immunological memory
includes physical barriers such as skin, chemicals in the blood, and immune system cells that attack foreign cells in the body.

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2
Q

adaptive immune response

A

acquired immune system

specific to antigen
lag time from exposure to response
immunological memory after exposure

composed of highly specialised, systemic cells and processes that eliminate pathogens or prevent their growth

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3
Q

innate humoral response

A

chemicals circulating in the blood
complement system
membrane attack complex

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4
Q

adaptive cell-mediated response

A

mediated by t-cells

- regulate activity of b-cells

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5
Q

professional phagocytes

A 
monocytes
macrophages
neutrophils
tissue dendritic cells
mast cells
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6
Q

when bacteria are taken up by an endosome

A

pH of phagosome drops
environment becomes more hostile for bacteria
- signalling pathways triggered
- fusion with lysosome to form phagolysome

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7
Q

phagolysosome

A

lysosome contains potent chemicals to destroy bacteria e..g lysozyme (antibacterial agent)

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8
Q

action of lysozyme on phagolysosome

A

vesicle ruptures and releases

damage signal recruits other immune cells

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9
Q

how do innate immune cells detect viral infection

A

pattern recognition receptors (PRRs)

  • present on cell surface or in intracellular compartments
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10
Q

types of PRRs

A

TLRs
NLRs
receptor kinases

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11
Q

how do TB pathogens prevent normal immune pathways

A 
use mannose receptors
no inflammatory response initiated
sits in early endosome
produce proteins that prevent fusion with lysosome
no phagolysosome formation
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12
Q

toll-like receptors

A 
membrane spanning
both intra and extra cellular portions
come as pairs (dimeric)
e.g. TLR1 pairs with TLR2
recognise and bind to ligands of microbes

recognise PAMPs

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13
Q

TLRs activate immune response when they bind

A

recruit adaptor proteins within cytosol

antigen-induced signal transduction pathway

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14
Q

nod-like receptors

A

cytoplasmic bound - not membrane
pick up bacteria if escaped from endosome
recognise presence of PAMPs
NOD - nucleotide-binding oligomerization domain
LRRs - leucine rich repeats

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15
Q

Pathogen Associated Molecular Patterns -PAMPs

A

activate innate immune responses
- protect host from infection

elevate protein levels
transduce signals through cell to increase transcription of cytokine

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16
Q

examples of PAMPs

A

flagellin
peptidoglycan
lipoprotein

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17
Q

bacteria aim to escape the vacuole

A

bacteria secrete toxin called cytolysin - lyses membrane

cytolysin is cholesterol dependent - attacks hosts membranes

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18
Q

listeria secretes listeriolysin extracellularly

A

lower pH causes more listeriolysin to be produced
phagosome ruptures
bacteria becomes intracellular and spreads
recruits actin tails for movement
produces a phospholipase

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19
Q

process of Salmonella

A

use TLRs to ensure they get to protected environment:

  • taken up and recognised by TLRs
  • bacteria hijacks TLRs
  • signalling creates acidic pH of vacuole

reaches salmonella-containing vacuoles(SCV) - protective niche

then secrete proteins into the cell to prevent further damage:

secreted effector proteins
prevent fusion with lysosome

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20
Q

process of shigella

A
  • enters M cells (sensory gut molecules)
  • enters into macrophage
  • induces cell death (secretion of effector proteins into cytoplasm -T3SS)
  • recognised by intracellular NLRs
  • plasma membrane ruptures
  • bacteria escape and enter neighbouring cells
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21
Q

T3SS

A

type 3 secretion system

used by pathogenic gram-ve bacteria
detect eukaryotic organisms
secrete effector proteins that help bacteria infect cells

22
Q

autophagosome formation

A

LC3 (myosin light chain 3) and ubiquitination come together on membrane

membrane ‘isolation’ sac elonagtes anf close forming double membrane vesicle

23
Q

autolysosome formation

A
  • outer membrane fuses with a lysosome
  • degradation of cytoplasmic contents
  • broken down products can be re-used e.g. amino acids
24
Q

autophagy

A

intracellular degradation system

targets portions of cytoplasm and delivers cytoplasmic constituents to the lysosome

beneficial for clearing infectious diseases

25
Q

control of autophagy

A

Type 3 secretion system - T3SS

IcsB - intracellular spread

26
Q

pro-inflammatory cytokines

A

interleukins
interferons
tumour necrosis factor (TNF-alpha)

27
Q

process of phagocytosis

A

bacteria taken up by phagocytosis
bacteria destroyed within phagolysosome
phagocytes act as APCs - antigen presenting cells
parts of bacteria (antigens) appear on the surface of the phagocyte
presented to a helper T cell
helper T cell activated

28
Q

antigens present to..

A

MHC molecules

29
Q

tri-molecular complex

A

key in recognition

made up of :

  • MHC
  • peptide
  • T cell receptor
30
Q

where are peptides held

A

in the grooves of the MHC I and II molecules

31
Q

CD1 molecule

A 
MHC-like structure
present glycolipids (not peptides) to natural killer t cells
32
Q

CD8+ T cells recognise antigens presented by …

A

MHC I molecules

33
Q

CD4+ t cells recognise antigens presented by …

A

MHC II molecules

34
Q

structure of MHC I

A

2 polypeptides and a beta-2 microglobulin component

35
Q

antigens presented by MHC I originate from the …

A

cytosol

36
Q

antigens processed by proteosomes in the cytosol are loaded…

A

through the endoplasmic reticulum onto antigen presenting cells (MHC I)

37
Q

when CD8+T cells are stimulated…

A

memory cells are activated

CD8 releases perforin molecules and granzymes which attack infected host and destroy

38
Q

2 killing mechanisms by cytotoxic t cells

A

perforin

CD95 or FasL pathway

39
Q

perforin pathway

A

perforin molecules delivered from cytoplasmic granules
fuse with membrane of APC
pores form allowing granzymes to enter infected cell
cause apoptosis

40
Q

CD95 or FasL pathway

A 
recognition system of cell death molecules
FasL expression increases on CTL
binds to Fas on the APC
Generation of proteases
apoptosis initiated
41
Q

structure of CD4 cells

A

2 polypeptides
groove for peptide to sit in
no beta-2 microglobulin

lots of co-receptors in addition to tri-molecular complex

42
Q

CD4 T cells recognise antigens that originate directly from …

A

the phagosome

43
Q

CD4 T cells

A

helper T cells
produce many cytokines - depending on how they are activated
help Cd8 T cells
affect B cells - antibody production

44
Q

production of cytokines and chemokines

A

modulates an immune response

45
Q

after exposure to TB, if innate immunity is inadequate then

A

infection occurs

46
Q

if TB infection occurs and adaptive immunity is inadequate then

A

latent infection occurs

bacteria is contained in a granuloma

47
Q

process of infection with TB

A

TB taken up by macrophages
immune cells recruited by chemokines e.g. neutrophils

innate granuloma - TB is surrounded by immune cells
inflammatory cytokines recruit D cells e.g. TNF-alpha

immune granuloma - chronic granuloma

48
Q

chronic granuloma

A

fibrotic capsule

surrounded by fibroblasts

49
Q

if CD4 levels are low…

A

then probably immunocompromised

50
Q

proteins in membranes of vacuoles

A

MHC I and II

Medical Micro (10 decks)

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