Innate immune system

Question 1

innate vs adaptive immune system

Answer 1

[innate]

-common set of responses turned on by most microbial agents
-“non-specific”
-fixed

[adaptive]

-individual response to specific antigen exposure
-capable of change during response - “adaptation”

Question 2

4 components of innate immune system

Answer 2

physical barriers

cellular components

complement system and mediators of inflammation

cytokines

Question 3

physical barriers

Answer 3

epithelial surfaces (skin, GI/respiratory/urinary tract)

secrete anti-microbial substances (defensins)

Question 4

what increases the secretion of anti-microbial substances

Answer 4

cytokines (IL-1 + TNF-alpha) -> pro-inflammatory

Question 5

what cells does epithelia contain that help with immunity?

Answer 5

lymphocytes

mast cells

Question 6

relationship between monocytes and macrophages

Answer 6

monocytes differentiate into macrophages

Question 7

mannose

Answer 7

carbohydrate residue found on microbe cell wall

not found on human cells

Question 8

opsonins

Answer 8

protein components that coat microbes and enhance ability to be phagocytosed

Question 9

what occurs when a pathogen binds to receptors on innate cells?

Answer 9

phagocytosis of pathogen by macrophages or neutrophils

killing of infected cells by NK cells

presentation to T cells by APCs (dendritic cells)

Question 10

toll-like receptors

Answer 10

found on most cells of innate immune system

respond to variety of microbial markers
-> LPS
-> Ds RNA
-> Bac peptidoglycans

result in upregulation of inflammatory gene expression
-> TNF-alpha
-> IL-1/12
-> E-selectin
-> iNOS

increased expression/overactivation linked to pathology of Alzheimer’s

Question 11

main physiological role of toll-like receptors

Answer 11

[detection and elimination of pathogens]

trigger release of proinflammatory cytokines to stimulate innate immune response

Question 12

TLR agonists

Answer 12

have potential to stimulate immune system to fight infection/cancer

Question 13

TLR antagonists

Answer 13

have potential to dampen immune system for treatment of chronic inflammation

Question 14

lipopolysaccharides (LPS)

Answer 14

endotoxin

product of gram -ve bacteria cell wall

induces inflammation

potent activator of macrophages inducing cytokine release and reactive oxygen (superoxides) burst

Question 15

symptoms of systemic inflammatory response syndrome (SIRS)

Answer 15

fever

neutrophilia

septic shock

Question 16

which cells mediate phagocytosis

Answer 16

neutrophils and macrophages

Question 17

which type of cells are first on the scene of infection?

Answer 17

neutrophils

Question 18

phagocytosis

Answer 18

bacterium becomes attached to membrane evaginations (= pseudopodia)

bacterium is endocytosised => forms phagosome

phagosome fuses with lysosome

lysosomal enzymes digest captured material

digestion products are released from cell

Question 19

enzymes in lysosomes

Answer 19

[degrading enzymes]

lysozyme

collagenase

elastase

ROIs and NO

Question 20

what draws WBCs from tissues to site of infection?

Answer 20

chemotactic signals

Question 21

reactive oxygen species

Answer 21

superoxide

hydrogen peroxide

nitro oxide
-> formed from arginine by iNOS (+ H2O2 = peroxynitrite)

Question 22

how do infected cells die?

Answer 22

via apoptosis

Question 23

“Mother Turkey response”

Answer 23

Mother turkeys will kill chicks if they don’t sound like chicks (have to keep chirping)

NK cells will kill cells that don’t express certain proteins

Question 24

zymogens

Answer 24

group of proteins which gain enzymatic activity by cleavage

Question 25

complement system

Answer 25

= cascade of plasma proteins activated by microbes resulting in their destruction

Question 26

how is the complement system used as a drug target

Answer 26

excessive complement activation = high levels of inflammation

Excessive complement activation/deposition/tissue damage observed in COVID-induced respiratory distress

Question 27

how is the complement system used as a drug target - meningitis

Answer 27

antibodies against C5 can reduce neutrophil infiltration

also decrease bacterial lysis by MAC complex

C5a/C5aR antibodies may be better

Question 28

TNF/IL-1

Answer 28

Majority produced by LPS challenged macrophages

Pro-inflammatory cytokines

Stimulate neutrophil migration to site of infection

Question 29

IL-12

Answer 29

Produced by mac and dendritic cells

Promotes NK cytolysis

Stimulates IFNɣ production in T and NK cells

IFNɣ stimulates mac to kill microbe