3 - innate immunity

Question 1

examples of potentially pathogenic microorganisms

Answer 1

viruses
fungi
parasites
bacteria

Question 2

1st defensive barrier of body

Answer 2

skin

Question 3

breaking of skin - cuts

Answer 3

exposes body tissues to bacteria and fungal infections

Question 4

main portals of entry to the body

Answer 4

mucosal epithelia of …
1 - GI tract
2- respiratory tract
3 - urogenital tract

Question 5

why does immune system find parasites hard to remove

Answer 5

too big

tries to surround and encapsulate them

Question 6

PAMPs

Answer 6

Pathogen associated molecular patterns

recognised by an array of PRRs
conserved or specific

Question 7

where are innate immune cells found

Answer 7

sitting under skin of lung surfaces

Question 8

features of innate immune cells

Answer 8

always there
no prior activation required
encoded in germline
under constant surveillance

Question 9

where are immune cells derived from

Answer 9

pluripotent haematopoietic stem cell

Question 10

HSC differentiation

Answer 10

divides to replace itself and produce a progenitor cell with potential to form all 3 lineages

Question 11

myeloid lineage

Answer 11

produces phagocytic cells and inflammatory cells
innate
protect epithelial surfaces

Question 12

mast cells role

Answer 12

sentinel role

differentiate and sit in tissues waiting to be activated

Question 13

basophils/eosinophils role

Answer 13

circulating cells

recruited from blood stream to infected tissue when signal is received

Question 14

killing mechanism of baso/eosino/mast cells

Answer 14

attack pathogens too large to be internalised

• degranulate when signal received on outside of cell
• release toxic contents creating hostile environment or directly kills pathogen

Question 15

granulocyte granules

Answer 15

contain toxic components
e.g. histamines (important for allergies)
proteases

Question 16

mechnikov 1898

Answer 16

discovery of phagocytosis
observational study of sticking thorns into cells
realised that migratory cells surround site of damage in animals with a vascular system

Question 17

front line effector cells

Answer 17

macrophages and neutrophils

Question 18

role of macrophages

Answer 18

sentinel
surveillance
send chemical signals to recruit more neutrophils (more effective)
phagocytic cells

Question 19

dendritic cells

Answer 19

similar to macrophages
however..
dont fully destroy pathogens

Question 20

action of DCs

Answer 20

break up pathogen and present fragments on cell surface to cells of adaptive immunity
ANTIGEN PRESENTATION

Question 21

monocytes

Answer 21

type of WBC/leukocyte

differentiate into dendritic cells and macrophages

Question 22

granulocytes

Answer 22

leukocytes (neutrophils)
basophils
mast cells
eosinophils

Question 23

natural killer (NK) cells

Answer 23

specialised cytotoxic T lymphocyte

innate

Question 24

types of macrophage receptors

Answer 24

scavenger receptors
complement receptors
receptors for conserved components of pathogens

Question 25

Fc receptors

Answer 25

from Ig superfamily
found on surface of immune cells
recognise antibody (produced by adaptive immunity) binding to outside of pathogen

Question 26

2 methods of innate activation

Answer 26

direct

indirect

Question 27

direct activation of innate immunity

Answer 27

PAMP recgnised on pathogen by PRR on immune cell

Question 28

indirect activation of innate immunity

Answer 28

if rececptors cannot grasp pathogen e.g. pathogen has slime capsule
delay
adaptive immunity activated
antibodies produced which opsonise pathogen
recognised by Fc receptor - phagocytosed

Question 29

define opsonin

Answer 29

soluble component of immune system

coats microorganisms and stimulates their uptake by phagocytosis

Question 30

‘ruffling’

Answer 30

motile cells migrate to cell membrane
actin polymerisation takes place
recognised by Fc receptors
dragged into phagosome

Question 31

phagocytic cell roles

Answer 31

1 - release cytokines and chemokines

2 - activate adaptive immune response

Question 32

chemokine

Answer 32

chemotactic cytokine

lays trails for migration of cells to site of infection

Question 33

example of chemokine

Answer 33

e.g. IL-8/CXCL-8

Question 34

cytokines

Answer 34

signalling molecules
increase permeability of blood vessels
allows cells to move out towards site of infection
inflammatory response can occur

Question 35

cytokine receptors

Answer 35

JAK/STAT
STAT molecules are phosphorylised and dimerise
STAT dimer translocates to nucleus and initiates transcription

Question 36

transendothelial migration

Answer 36

neutrophil rolls along epithelium of blood vessel
squeezes through loosened tight junction into adjacent connective tissue
migrates along concentration gradient of chemokine towards site of infection

Question 37

why are selectins important

Answer 37

interactions with selectins are low affinity

constantly made and broken allowing rolling along surface of epithelium of blood vessel

Question 38

what do fluid matrices e.g. tears contain

and why are they important in immunity

Answer 38

antibacterial peptides
toxic proteins

upregulated when pathogen component recognised
important for recruiting neutrophils to inflammatory sites

Question 39

examples of antibacterial peptides and where are they found

Answer 39

B-defensins - lungs/skin
a- defensins - paneth cells of intestinal tract
lysozyme - fluid bathing cornea (potent)
cathelicidins

Question 40

cathelicidins

Answer 40

produced by activated neutrophils and epthelial cells
signal thorugh formyl peptide receptors (GPCR)
aids neutrophil recruitment when bound

Question 41

fMLP - formyl-methionyl peptide

Answer 41

bacterial peptide (chemotactic)
chemoattractant –> activates neutrophil recruitment
cleaved by peptidase and released into extracellular space
binds to receptor on outside of neutrophils