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CST - BIOSCI107 > B & I - Innate Immunity > Flashcards

B & I - Innate Immunity Flashcards

1
Q

what does innate immunity entail

A

recognition of traits shared by broad ranges of pathogens, using a small set of receptors

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2
Q

is innate immunity slow or fast

A

innate immunity has rapid response

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3
Q

is innate immunity faster or slower than adaptive immunity

A

faster

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4
Q

what are the barrier defenses of innate immunity

A

skin, mucous membranes, secretions

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5
Q

what are the internal defenses of innate immunity

A

phagocytic cells, natural killer cells, antimicrobial cells, inflammatory cells

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6
Q

what does the humoral system consist of

A

soluble factors such as antimicrobial peptides that directly kill bacteria and antibodies which are produced by B lymphocytes

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7
Q

what does cellular immunity consist of (think of cells)

A

myeloid cells (innate) or lymphoid cells (adaptive)

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8
Q

does the innate immune response change or strengthen over time

A

no

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9
Q

is your innate or adaptive immunity the immediate and first-line defense against an infection

A

innate immunity

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10
Q

what do all living things have

A

some ability to discriminate between self and non-self

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11
Q

which (innate or adaptive) is more primordial

A

innate

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12
Q

does innate response have memory

A

no - what you are born with is what you will always have

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13
Q

what does defence against viruses rely on

A

cellular immunity - need to be able to distinguish infected from normal cells

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14
Q

what type of pathogens are bacteria (extracellular or intracellular?)

A

mostly extracellular (live outside cells)

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15
Q

what does defense against bacteria rely on

A

innate mechanisms and phagocytosis

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16
Q

defence against complex multicellular organisms, such as protozoa and parasites, relies on (direct killing by ___________ __________ released by _____________ _______________ __________)

A

direct killing by chemical mediators released by special myeloid cells

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17
Q

what are the chemical mediators (and how are they released and give one example)

A

granules filled with cytotoxic chemicals; degranulation releases the toxic inflammatory chemicals such as histamine

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18
Q

what are the three interlinked processes of innate immunity in mammals

A
  1. Complement
  2. myeloid cells and phagocytosis (neutrophils and macrophages)
  3. pattern recognition receptors
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19
Q

describe complement step

A

opsonization of microbes by blood proteins and the production of anaphylatoxins that attract and activate phagocytes

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20
Q

describe phagocytosis step

A

engulfment of the microbe by phagocytes (neutrophils and macrophages) that destroy the organism

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21
Q

describe PRR step (basically what are PRR)

A

receptors found on many myeloid cells that recognize complex microbial molecular patterns

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22
Q

what are most bacteria distinguished by

A

the gram stain

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23
Q

describe the features of a gram-positive bacteria

A

gram-positive bacteria have a thick peptidoglycan cell wall as a defense

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24
Q

describe the features of a gram-negative bacteria

A

have a thin peptidoglycan layer surrounded by an outer membrane

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25
Q

how are gram-positive bacteria destroyed

A

requires phagocytosis

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26
Q

can gram-positive bacteria be killed directly by complement?

A

no

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27
Q

how are gram-negative bacteria destroyed

A

can often by lysed directly by complement membrane attack complex

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28
Q

what do beta-lactam antibiotics such as penicillin do

A

block peptidoglycan synthesis

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29
Q

the peptidoglycan wall is involved in antibiotics working because

A

antibiotics interrupt the synthesis of the bacterial wall

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30
Q

how do neutrophils find infections from the confines of a blood vessel

A

using neutrophil extravasation

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31
Q

what are the five steps of neutrophil extravasation

A
  1. activation
  2. tethering
  3. adhesion
  4. diapedesis
  5. chemotaxis
32
Q

what is the definition of neutrophil extravasation?

A

neutrophil extravasation is the ability of neutrophils to identify the site of infection by recognizing endothelial cells on the inner wall of the capillary that is closest to the infection

33
Q

describe activation step

A

chemokines from tissue injury or inflammation activate the local endothelial cells lining the inside of an adjacent capillary wall

34
Q

describe tethering step

A

neutrophil tethers to the inside capillary wall

35
Q

what is the tethering step mediated by

A

selectins upregulated on endothelial cells and slalyl Lewis X (sLe^x) - a carbohydrate antigen on neutrophils

36
Q

describe adhesion step

A

strong binding between neutrophil integrins and ICAM-1 on the endothelium. neutrophil immobilizes and flattens

37
Q

describe diapedesis step

A

neutrophil squeezes between endothelial cells into the interstitial space

38
Q

describe chemotaxis step

A

neutrophil migrates along a chemical gradient to the site of infection

39
Q

what happens when chemoattractants such as C5a is released

A

they radiate away from the bacteria and are sensed by the leading edge of the neutrophil

40
Q

when neutrophils migrate up the chemoattractant gradient what do they do to actin filaments

A

polymerize actin filaments at their leading edge and de-polymerize those filaments at their trailing edge

41
Q

name the complement receptors

A

CR1, CR2, CR3, CR4

42
Q

what are these complement receptors (on neutrophils) and what do they do?

A

they are myeloid cell receptors that bind activated complement deposited on bacteria

43
Q

what is the main neutrophil receptor and what does in bind to

A

CR1, binds to C3b

44
Q

what initiates phagocytosis

A

cross-linking of the surface CRs

45
Q

what is opsonization

A

the process of coating microbes with complement proteins to form complex complement convertases ready for phagocytosis

46
Q

what are the three pathways of activation

A

classical, lectin and alternative

47
Q

neutrophils and macrophages engulf _________ _______ but ignore ___-_________ ____

A

neutrophils and macrophages engulf opsonized bacteria but ignore non-opsonized cells

48
Q

what are FcR

A

the receptors that recognize antibodies that have coated the surface of bacteria

49
Q

what are IgG and IgM

A

antibodies that recognize various antigens - epitopes on the surface of bacteria. they bind and coat the bacteria in antibody

50
Q

list the 7 steps of FcR (antibody) mediated phagocytosis

A
  1. antibody (IgM and IgG) bind to bacterial antigens
  2. exposes the antibody Fc region
  3. neutrophil FcR binds to multivalent Fc
  4. activates phagocytosis
  5. membrane invaginates forming a phagosome
  6. fuses with a lysosome to form a phagolysosome
  7. phagolysosome acidifies and superoxides kill the bacteria
51
Q

what does the C1 component of complement bind

A

the back end of the bacteria - Fc receptors will also bind to the back end of the antibodies which initiates the same phagocytic engulfment

52
Q

name the 5 steps of phagocytosis

A

ingestion, fusion, acidification, digestion and exocytosis

53
Q

what happens in ingestion

A

bacterium is captured by receptors, membrane invaginates into a phagosome

54
Q

what happens in fusion

A

the phagosome and lysosome fuse to form a phagolysosome

55
Q

what happens in acidification

A

the phagolysosome acidifies with H+ pumped in

56
Q

what happens in digestion

A

acidification activates protease and stimulates the production of superoxides such as H2O2 and HOCl which kill bacteria

57
Q

what happens in exocytosis

A

expulsion of the digested microbe

58
Q

what do PRRs do

A

bind complex molecules that are unique to microbes

59
Q

What are PAMPs and what are they recognized by

A

pathogen-associated molecular patterns and they are unique to microbes and are recognized by a set of pattern recognition receptors

60
Q

do PAMPs change much

A

no they are part of the innate immune system and thus are evolutionarily stable

61
Q

what do PAMPs do

A

stimulate the power switch for the adaptive response

62
Q

what is the best-known PRR

A

toll-like receptors (TLR)

63
Q

what does activation of TLR stimulate

A

a strong innate response through an important inflammation pathway

64
Q

what happens if you don’t have the inflammation pathway activated through TLR

A

you don’t get an effective response - it drives everything

65
Q

what is the best example of a PAMP

A

LPS (lipopolysaccharide)

66
Q

what is LPS

A

membrane component of all gram-negative bacteria

67
Q

what is LPS recognized by

A

TLR4

68
Q

what are TLRs responsible for

A

driving the innate response

69
Q

what do tiny amounts of LPS induce

A

a very powerful innate response

70
Q

LPS is a ______

A

pyrogen

71
Q

what does LPS do when injected into the bloodstream

A

causes a fever

72
Q

what is a pyrogen

A

something that induces a fever

73
Q

does LPS need to be removed from anything that is injected into humans?

A

yes

74
Q

what does release of LPS by gram-negative bacterial infections do

A

leads to life-threatening septic shock

75
Q

LPS is used by PRR to

A

sense invasion

CST - BIOSCI107 (13 decks)

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