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MIMM 214 > Innate Immunity 1 > Flashcards

Innate Immunity 1 Flashcards

1
Q

what 2 types of surfaces does a pathogen enter through?

A
  1. mucosal
  2. epithelial
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2
Q

what allows a pathogen to cause infection?

A

pathogen must breach one of the barriers thru various routes of entry

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3
Q

why is human skin resistant to E. coli colonization despite exposure?

A
  • nutrients, pH
  • can’t breach
  • skin can make antimicrobial protein against gram-neg
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4
Q

what are 4 examples of epithelial surfaces that are barriers?

A
  1. skin
  2. gut epithelium
  3. respiratory epithelium
  4. mucosal membranes
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5
Q

how do saliva, hair, mucous, and tears provide innate immunity?

A

contain molecules that are antimicrobial

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6
Q

what are 2 types of protective substances produced by the epithelial layers?

A
  1. acidic pH
  2. antimicrobial peptides
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7
Q

what are 4 cell types involved in innate immunity?

A
  1. neutrophils + other granulocytes
  2. monocytes/macrophages
  3. dendritic cells
  4. NK cells + other innate lymphoid cells (ILCs)
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8
Q

describe the different types of monocytes/macrophages

A

all have same function but different types based on tissue

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9
Q

what are the 2 types of mature dendritic cells?

A
  1. conventional DCs
  2. plasmacytoid DCs
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10
Q

what are 3 types of molecules involved in innate immunity?

A
  1. enzymes
  2. anti-microbial peptides
  3. complement
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11
Q

what is an example of an enzyme involved in innate immunity and its function?

A

lysozyme –> digests peptidoglycan of gram-pos bacteria

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12
Q

what is an example of an anti-microbial peptide involved in innate immunity and its function?

A

defensins –> disrupt the cell membrane

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12
Q

what is the definition of phagocytosis?

A

engulfument and internalization of pathogens/pathogen components upon binding to receptors on surface of phagocytes

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13
Q

what are the 3 types of phagocytes?

A
  1. macrophages
  2. granulocytes (neutrophils)
  3. immature DC
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14
Q

phagocytosis can lead to: (3)

A
  1. removal and killing of pathogen
  2. cleaning debris from killing pathogens
  3. production of antigenic peptides to present to T cells
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15
Q

what are the 2 types of phagocytes that produce antigenic peptides to present to T cells?

A
  1. DCs
  2. macrophages
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16
Q

how do phagocytes recognize pathogens?

A

by receptors, usually PRRs

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17
Q

do all PRRs induce phagocytosis? are all receptors involved in phagocytosis PRRs?

A

no

no

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18
Q

how does indirect phagocytosis occur?

A

phagocyte recognize opsonins on pathogen surface

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19
Q

what are opsonins?

A

soluble proteins that are bound to microbial surfaces

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20
Q

what is another name for opsonins?

A

soluble pattern-recognition patterns

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21
Q

what is the role of opsonins?

A

enhance phagocytosis

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22
Q

what is the enhancement of phagocytosis called?

A

opsonization

23
Q

what is an example of an opsonin?

A

antibody

24
Q

what are the 5 steps of phagocytosis?

A
  1. phagocytosis initiated by receptors interacting with microbes (PAMP)
  2. pseudopodia extend from the phagocytic cell
  3. pathogen is internalized in a phagosome
  4. phagosome fuses with 1+ lysosomes to make a phagolysosome and lysosomal contents are released
  5. phagolysosome acidifies and acquires antimicrobial peptides + enzymes to kill microbe
25
Q

what is a phagosome?

A

large membrane-enclosed endocytic vesicle that internalizes pathogens

26
Q

what allows for the acidification and production of antimicrobial peptides/enzymes?

A

the fusion of phagosome and lysosome

27
Q

what is unique about neutrophil phagocytosis?

A

they contain primary and secondary granules in cytoplasm (INSTEAD OF LYSOSOMES) which fuse with phagosomes and produce antimicrobial peptides

28
Q

what does the phagolysosome do to kill microbes? (4)

A
  1. produce antimicrobial proteins + peptides
  2. low pH
  3. hydrolytic enzymes
  4. oxidative attack
29
Q

what are the 2 types of hydrolytic enzymes produced during phagocytosis?

A
  1. lysozyme
  2. proteases
30
Q

what does oxidative attack do?

A

creates ROS to damage microbial membranes and intracellular components

31
Q

why can phagocytes produce ROS?

A

phagocytes have a unique NADPH oxidase enzyme complex (phagosome NADPH oxidase)

32
Q

what happens when ROS is produced by NADPH oxidase?

A

increased oxygen consumption –> respiratory burst

33
Q

does the phagolysosome affect innate or adaptive immunity?

A

both!

34
Q

what are the 3 roles of the phagolysosome in innate immunity?

A
  1. pathogen killing
  2. pathogen processing
  3. pathogen presentation to sensory cytosolic receptors
35
Q

what are the 3 roles of the phagolysosome in adaptive immunity?

A
  1. antigen degeneration
  2. antigen processing
  3. antigen presentation
36
Q

what happens to cells that have undergone apoptosis?

A

they are cleared by phagocytes

37
Q

how are cells cleared once they die?

A

the dead/dying cells express DAMPs which signal for them to be eaten

38
Q

what does DAMP stand for?

A

Damage-Associated Molecular Patterns

39
Q

what is CD47?

A

expressed by healthy cells (most cell types) that signal for them NOT to be eaten

40
Q

how does CD47 work?

A

CD47 binds SIRPalpha (signal regulatory protein alpha) on macrophages to INHIBIT PHAGOCYTOSIS

41
Q

What type of cells express elevated levels of CD47?

A

tumour cells

42
Q

where are macrophages located?

A

they are located at tissue

43
Q

where are neutrophils located?

A

they are recruited to the site of infection

44
Q

what is pus?

A

dead and dying neutrophils

45
Q

what do neutrophils produce?

A

Neutrophil Extracellular Traps (NETs)

46
Q

what percent of neutrophils produce NETs?

A

20-60%

47
Q

what is the role of NETs? (2)

A
  1. traps microorganisms to prevent spread
  2. produce antimicrobial peptides/enzymes
48
Q

what can granule enzymes in neutrophils do to microbes?

A

they enter the nucleus to modify histones so CHROMATIN DECONDENSES

49
Q

what allows for the production of NETs?

A

once chromatin is decondensed, PM ruptures and cytoplasm/nucleoplasm are released to form NETs

50
Q

what is the “macrophage of the brain”

A

microglia

51
Q

what is the role of microglia?

A

establishing proper neuronal connections for brain development, memory, learning

52
Q

what is multiple sclerosis?

A

inflammatory disease w myelin/neuron breakdown, causing toxic debris

53
Q

how is toxic debris in MS removed?

A

by microglia and other macrophages (but this does not fix the missing neurons!)

54
Q

in general, what are microglia required for?

A

CNS repair

55
Q

what happens when the microglia receptor is KO?

A

cells cannot migrate to site of damage –> no phagocytosis

MIMM 214 (33 decks)

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