Innate Immune System

Question 1

Immune system definition

Answer 1

a network of specialised cells, tissues and soluble factors that cooperate to kill and eliminate invading pathogens and cancer cells

Question 2

autoimmunity definition

Answer 2

the immune system attacking the cells of the body when it shouldn’t as they are healthy

Question 3

what happens if the immune system overreacts
what happens if the immune system underreacts

Answer 3

over: autoimmunity, allergy
under: high risk of cancer, can’t fend of pathogens

Question 4

what are the structural defences of the innate immune system

Answer 4

tough outer surface which is impermeable to microbes
inner surface bathed continuously in secretions (acid and mucous)
commensal organisms
anti-microbial peptides

Question 5

what are the specialised cells and molecules of the innate immune response?

Answer 5

phagocytic cells
degranulating cells
secreted proteins

Question 6

which cell types are phagocytic and what is their role

Answer 6

neutrophils
monocytes and macrophages
dendritic cells
NK cells
first responders, orchestrate initiation of response, recognise, ingest and kill bacteria and yeast

Question 7

which cell types are degranulating

Answer 7

mast cells
eosinophils
basophils

Question 8

what types of proteins are secreted as part of the innate immune response

Answer 8

chemokines
cytokines
complement (induced)

Question 9

which cell types are tissue-resident innate immune cells

Answer 9

macrophage
mast cell

Question 10

macrophage role

Answer 10

phagocytosis
regulation of inflammation
antigen presentation
tissue repair

Question 11

mast cell role

Answer 11

pro-inflammatory
parasitic killing mechanisms
linked to allergy

Question 12

what are PAMPs

Answer 12

pathogen-associated molecular patterns

Question 13

what are PRRs

Answer 13

pattern recognition receptors

Question 14

how do immune cells recognise pathogens as ‘non-self’

Answer 14

pathogens express PAMPs which are recognised by specific PRRs expressed by immune cells

Question 15

what are target pathogens engulfed into during phagocytosis
what do they fuse with

Answer 15

phagosomes
lysosomes (to form phagolysosomes)

Question 16

what do macrophages do in response to degrading a pathogen and its debris being released into the intracellular fluid

Answer 16

expresses pathogen-derived peptides on MHC-II molecules

Question 17

what is degranulation of mast cells

Answer 17

release of pre-formed pro-inflammatory substances

Question 18

what do mast cells do in response to danger signals from damaged cells

Answer 18

degranulation
gene expression (production of new pro-inflammatory substances)

Question 19

what causes acute inflammation

Answer 19

bacteria trigger macrophages to release cytokines and chemokines
vasodilation and vascular permeability increase causing redness, heat and swelling
inflammatory cells migrate into tissue releasing inflammatory mediators that cause pain

Question 20

role of neutrophils

Answer 20

activation of the alternative complement pathway
phagocytosis
pro-inflammatory
bacterial killing mechanisms

Question 21

what do all three complement activation pathways eventually lead to

Answer 21

C3 cleavage to C3b and C3a

Question 22

what is the complement system

Answer 22

a cascade of chemical reactions that promote acute inflammatory reactions

Question 23

what does the complement system lead to

Answer 23

opsonisation of pathogens
direct pathogen killing (membrane attack complex)
leukocyte recruitment
lysis

Question 24

what are the killing mechanisms of neutrophils

Answer 24

phagocytosis
degranulation
neutrophil extracellular traps

Question 25

which chemokine recruits neutrophils to the site of an infection

Answer 25

TNF alpha