effectors of innate immunity

Question 1

what proportion of blood is white blood cells

Answer 1

<1%

Question 2

what proportion of leukocytes are neutrophils

Answer 2

> 60%

Question 3

what proportion of leukocytes are lymphocytes

Answer 3

~25%

Question 4

what proportion of leukocytes are monocytes

Answer 4

~5%

Question 5

what proportion of leukocytes are eosinophils and basophils

Answer 5

<5%

Question 6

what are leukocytes

Answer 6

all white blood cells

Question 7

what are lymphocytes

Answer 7

b and t cells

Question 8

what are monocytes

Answer 8

macrophage precursors

Question 9

cells of the innate immune system

Answer 9

neutrophils - also called granulocytes
macrophages
dendritic cells
natural killer cells
eosinophils
basophils
mast cells

Question 10

cells of the adaptive immune system

Answer 10

t helper cells
cytotoxic t lymphocytes
b cells

Question 11

what is complement

Answer 11

series of soluble proteins in the blood

Question 12

what are individual complement molecules called

Answer 12

c1, c2, c3 etc to c9

Question 13

is complement cellular or acellular

Answer 13

acellular

Question 14

what does the complement system activate through

Answer 14

a triggered enzyme cascade

Question 15

what 3 pathways do pathogens lead to the activation of complement by

Answer 15

1st - classical pathway
2nd - mannose-binding lectin pathway
3rd - alternative pathway

Question 16

what 3 things does complement activation lead to

Answer 16

anaphylotoxins (inflammation)
membrane attack complex (lysis)
opsonisation

Question 17

when does the classical pathway of complement activation occur

Answer 17

when there are antibodies present specific to a foreign antigen - e.g. on a bacteria, or soluble

Question 18

what are antibody complexes bound by

Answer 18

complement component C I q

Question 19

what does the classical pathway activate

Answer 19

subsequent complement components

Question 20

how does the alternative pathway activate

Answer 20

truly innate - main innate pathway
spontaneously activates and binds to nearby membranes - all molecules
host cells have control proteins on surface preventing further complement activation
bacterial cells dont - complement activates

Question 21

what complement component is involved in the alternative pathway

Answer 21

C3

Question 22

how does mannose-binding lectin work

Answer 22

activation through mannose-binding lectin binding to mannose (or similar carbs) on bacteria
mannose not present on surface of host cells so the lectin doesnt bind and complement is not activated

Question 23

process of complement lysis

Answer 23

membrane attack complex (MAC) forms in membrane of bacteria
barrel-like structure formed from multiple late complement components (C6-C9)
water rushes in, ions rush out, bacteria swells and bursts
can also happen to host/foreign cells marked for killing

Question 24

complement mediated anaphylatoxins

Answer 24

soluble complement components released on activation
anaphylotoxin release results in blood vessels becoming leaky (oedema) - results in infiltration of plasma proteins and recruitment of immune cells and activation of mast cells

Question 25

what are anaphylotoxins

Answer 25

toxins that can cause anaphylaxis

Question 26

opsonisation

Answer 26

membrane bound complement components opsonise pathogens - bind to surface of bacteria - phagocytes have complement receptors which bind membrane bound complement - encourage phagocytosis and killing

Question 27

the complement cascade

Answer 27

classical pathway - antigen, antibody IgG > c1 complex > c2b and c4b fragments > c3 convertase alternative pathway - c3 hydrolysis > c3b and c3a fragments > c3b cleaves c5 into c5a and c5b

Question 28

what happens after the complement cascade

Answer 28

cell swells and bursts c5b, c6, c7, c8 and c9 form the cylindrical membrane attack complex

Question 29

what does phagocyte mean and what do they do

Answer 29

phago = eating cyte = cell phagocytes - eat pathogens

Question 30

what cells are involved in allergic and anti-parasite responses

Answer 30

eosinophils, basophils and mast cells

Question 31

what do natural killer cells kill

Answer 31

virally infected/sick cells

Question 32

neutrophils

Answer 32

recruited rapidly to scene good at killing - many preformed granules very short lived (a few days) chief constituent of pus

Question 33

macrophages

Answer 33

macro = big, phage = eaters good at killing if activated also involved in tissue healing, clearance of dead cells, metabolism reside in tissue, and supplemented by monocytes

Question 34

dendritic cells

Answer 34

poor at killing rare reside in tissues initiate adaptive immune responses - take a message to t cells

Question 35

process of extravasiona

Answer 35

neutrophils need to get from circulation to site of inflammation

Question 36

what is the endothelium of the blood vessel altered by

Answer 36

inflammatory cytokines

Question 37

how do neutrophils extravate

Answer 37

neutrophil starts to roll along endothelium, then firmly adheres, and exits between endothelial cells (diapedesis)

Question 38

what do neutrophils follow

Answer 38

chemokine gradient to site of inflammation

Question 39

what is formed when phagocytes detect pathogens and engulf them

Answer 39

phagosome

Question 40

what do lysosomes fuse with and why

Answer 40

phagosome lysosome contains toxic products to kill/degrade pathogen

Question 41

what is the molecule called after the phagosome and lysosome fuse

Answer 41

phagolysosome

Question 42

what happens as more lysosomes fuse to the phagolysosome

Answer 42

it matures and H+ ions are pumped in

Question 43

what do neutrophils produce

Answer 43

hypochlorite (bleach)

Question 44

what is an antigen

Answer 44

a molecule that is recognised by the adaptive immune system

Question 45

what are adaptive immune cells randomly generated to express

Answer 45

a unique receptors which recognises a specific antigen (termed antigen-specificity)

Question 46

what can antigens be

Answer 46

self antigens or non-self antigens (e.g. pathogen or environmental)

Question 47

what are dendritic cells doing when they are in the periphery

Answer 47

constantly taking up antigen

Question 48

what happens if dendritic cells sense danger

Answer 48

they mature - get better at antigen presentation and upregulate different chemokine receptors - results in migration to lymphatics and into the draining lymph node where they present the antigen to t cells

Question 49

why is antigen presentation so complicated

Answer 49

to make sure an immune response isnt generated against harmless things (allergy/IBD) or own tissues (autoimmunity)

Question 50

2 signals for antigen presentation

Answer 50

signal 1 - specific antigen signal 2 - danger

Question 51

what can b cell receptors recognise

Answer 51

soluble antigen in its normal form

Question 52

what to do t cells need to recognise an antigen

Answer 52

has to have antigen presented to it on major histocompatibility complex (MHC) molecules on another cell - antigens must be chopped up into peptides, then loaded onto MHC molecules and presented on surface of a cell

Question 53

process of dendritic cells (pathogen/danger detection)

Answer 53

pathogen/damage (PAMPs/DAMPs) > immature DC in periphery > signal 1 - MHC + antigen, signal 2 - co-stimulation > mature DC in lymph nodes > CD4T > activation

Question 54

process of dendritic cells (environmental Ag apoptotic cells)

Answer 54

env. Ag ap. cells > immature DC in periphery > signal 1 - MHC + antigen, signal 2 - co-stimulation > immature/semit-mature DC in lymph nodes > t cells > anergy/death