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

B & I - Innate Immunity Flashcards

(75 cards)

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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
how are gram-positive bacteria destroyed
requires phagocytosis
26
can gram-positive bacteria be killed directly by complement?
no
27
how are gram-negative bacteria destroyed
can often by lysed directly by complement membrane attack complex
28
what do beta-lactam antibiotics such as penicillin do
block peptidoglycan synthesis
29
the peptidoglycan wall is involved in antibiotics working because
antibiotics interrupt the synthesis of the bacterial wall
30
how do neutrophils find infections from the confines of a blood vessel
using neutrophil extravasation
31
what are the five steps of neutrophil extravasation
1. activation 2. tethering 3. adhesion 4. diapedesis 5. chemotaxis
32
what is the definition of neutrophil extravasation?
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
describe activation step
chemokines from tissue injury or inflammation activate the local endothelial cells lining the inside of an adjacent capillary wall
34
describe tethering step
neutrophil tethers to the inside capillary wall
35
what is the tethering step mediated by
selectins upregulated on endothelial cells and slalyl Lewis X (sLe^x) - a carbohydrate antigen on neutrophils
36
describe adhesion step
strong binding between neutrophil integrins and ICAM-1 on the endothelium. neutrophil immobilizes and flattens
37
describe diapedesis step
neutrophil squeezes between endothelial cells into the interstitial space
38
describe chemotaxis step
neutrophil migrates along a chemical gradient to the site of infection
39
what happens when chemoattractants such as C5a is released
they radiate away from the bacteria and are sensed by the leading edge of the neutrophil
40
when neutrophils migrate up the chemoattractant gradient what do they do to actin filaments
polymerize actin filaments at their leading edge and de-polymerize those filaments at their trailing edge
41
name the complement receptors
CR1, CR2, CR3, CR4
42
what are these complement receptors (on neutrophils) and what do they do?
they are myeloid cell receptors that bind activated complement deposited on bacteria
43
what is the main neutrophil receptor and what does in bind to
CR1, binds to C3b
44
what initiates phagocytosis
cross-linking of the surface CRs
45
what is opsonization
the process of coating microbes with complement proteins to form complex complement convertases ready for phagocytosis
46
what are the three pathways of activation
classical, lectin and alternative
47
neutrophils and macrophages engulf _________ _______ but ignore ___-_________ ____
neutrophils and macrophages engulf opsonized bacteria but ignore non-opsonized cells
48
what are FcR
the receptors that recognize antibodies that have coated the surface of bacteria
49
what are IgG and IgM
antibodies that recognize various antigens - epitopes on the surface of bacteria. they bind and coat the bacteria in antibody
50
list the 7 steps of FcR (antibody) mediated phagocytosis
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
what does the C1 component of complement bind
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
name the 5 steps of phagocytosis
ingestion, fusion, acidification, digestion and exocytosis
53
what happens in ingestion
bacterium is captured by receptors, membrane invaginates into a phagosome
54
what happens in fusion
the phagosome and lysosome fuse to form a phagolysosome
55
what happens in acidification
the phagolysosome acidifies with H+ pumped in
56
what happens in digestion
acidification activates protease and stimulates the production of superoxides such as H2O2 and HOCl which kill bacteria
57
what happens in exocytosis
expulsion of the digested microbe
58
what do PRRs do
bind complex molecules that are unique to microbes
59
What are PAMPs and what are they recognized by
pathogen-associated molecular patterns and they are unique to microbes and are recognized by a set of pattern recognition receptors
60
do PAMPs change much
no they are part of the innate immune system and thus are evolutionarily stable
61
what do PAMPs do
stimulate the power switch for the adaptive response
62
what is the best-known PRR
toll-like receptors (TLR)
63
what does activation of TLR stimulate
a strong innate response through an important inflammation pathway
64
what happens if you don't have the inflammation pathway activated through TLR
you don't get an effective response - it drives everything
65
what is the best example of a PAMP
LPS (lipopolysaccharide)
66
what is LPS
membrane component of all gram-negative bacteria
67
what is LPS recognized by
TLR4
68
what are TLRs responsible for
driving the innate response
69
what do tiny amounts of LPS induce
a very powerful innate response
70
LPS is a ______
pyrogen
71
what does LPS do when injected into the bloodstream
causes a fever
72
what is a pyrogen
something that induces a fever
73
does LPS need to be removed from anything that is injected into humans?
yes
74
what does release of LPS by gram-negative bacterial infections do
leads to life-threatening septic shock
75
LPS is used by PRR to
sense invasion

CST - BIOSCI107 (13 decks)

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