The Innate Immune system Flashcards
Why we need an immune reponse
prevent infection & cancer
remove dead or non-functioning components
5 Pathogen classifications
Virus - hijacks host
Bacterium - prokaryote
Fungus - euaryote
Protozoal parasite - multiple hosts
Multicellular parasite - multiple life cycles
Pathogen definition
disease causing microorganism
What are the bodies physical barriers
Skin, Cilia, hair, mucosal surfaces, urine/tears (flushing), peristalsis
How does the skin prevent disease
- Sebaceous glands make oils preventing life
- desquamation (skin sheading)
How do mucosal surfaces prevent disease
mouth, lungs, GI tract ect
- Anti microbial proteins
- Protective gut bacteria that outcompete pathogens
what immune cells are found in the GI tract
Laminar propria (villi like)
Chemical defence examples
- lysozyme (saliva)
- Stomach acid
- urinary tract flushing
- mucus lining
- rapid pH change in body
What is Flora?
various microorganisms that live in the body without causing disease
what do Flora do
make it harder for other pathogens to reproduce
What is the order of defence in the body
1st - skin/mucosal layers
2nd - innate immune system
3rd - adaptive immune system
What are cytokines
cell signalling molecules (proteins)
what are the 2 groups of cytokines
pro-inflammatory (IS activating)
anti-inflammatory (dampen IS)
3 different types of cytokine
Interleukins
Interferons
chemkines
what do interleukins do
target leukocytes allowing communication
what do interferons do
prompt anti viral response
what do chemokines do
mediate cellular chemotaxis
can cytokines have different Reponses on different cells?
yes
can cytokines work together to increase response
yes
what do para, endo, autocrine cytokines do
para - act on other cells (most common)
auto - act on itself
endo - travel in blood to target
what does C-reactive protein do?
Help innate immune cells recognise pathogens
activates complement system
where is C-reactive protein produced
Liver
what are the 3 pathways of the complement system
Lectin
classical
alternative
what is the lectin pathway?
manos binding lectin binds to sugars on bacteria
what is the classical pathway?
C1 binding to pathogen antibodies
what is the alternative pathway?
Complement protein C3B binds to carbohydrate on bacteria
what happens after a complement system pathway is activated
protein C3 is cleaved = C3a and C3b
what does protein C3a do?
inflammation and mast cell activation
Causes C5 to be cleaved
what does protein C3b do?
opsonisation
Causes C5 to be cleaved
What does C5 produced when cleaved
C5a and C5b
What is the innate immune system and what does it do
1st cellular line of defence
non specific
initiates inflammation
what is a negative about the innate immune system
its reponse can damage surrounding tissue
5 signs of inflammation
Heat Redness Swelling Pain Loss of function
What causes inflammation?
mast cells
what do mast cells do when activated
degranulate and kickstart the inflammatory response
What happens local due to inflammation
vasodilation = ^ Blood flow
endothelial cells activated - junctions broken (more permeable blood vessels - recruits more blood)
What are neutrophils and what do they do?
most abundant immune cell, short lived, phagocyte, release antimicrobial products from granules
what is phagocytosis (6 stages)
- recognition
- engulfing
- encasing (phagosome)
- lysosomes fuse (phagolysosome)
- bacteria is killed (antibacterial compounds)
- component’s released
what is the respiratory burst?
NADPH converts 02 into superoxide
Superoxide dismutates to hydrogen peroxide or hypochlorous acid (both acid and will kill pathogens)
what is chemotaxis?
directed movement of a cell along a conc grad
migrate to site of infection) where conc is ^
how are leukocyte recruited?
they bind to P/E selectin allowing them to detect chemokines they will look for a gap in the blood vessel to get through into tissue
Other granulocytes & their targets
Basophils - rare, for allergies
Eosinophil - anti parasitic
what are nature killer cells and what do they do?
a lymphocytes
cause cell death of ‘stressed’ cells (cancerous/infected)
activate macrophages
what does NK Perforin & Granzyme do?
Perforin forms a pore on the pathogen
Granzyme goes through pore and kills the cell
how does pathogen recognition system work?
Pattern recognition receptors - find common pathogen characteristics
What PRR’s bind to
Pathogen associated molecular patterns on pathogen surfaces
what do toll-like receptors (PRR) do?
detect a variety of microorganism-derived molecular structures and active APC’s to produce pro-inflammatory cytokines
Pathogen associated molecular patterns (PAMPs) examples
lipoproteins Flagellin DNA RNA envelope proteins Sugars
what is an antigen?
any protein not recognised by the immune system (not derived from host)
what do antigen presenting cells (APC’s) do?
internalise proteins during phagocytosis and process them with major histocompatibility II (MHC II)
and then display them on the cell surface
what are Macrophages (APC’s) and what do they do
Monocyte-derived macrophages
kill pathogens with phagocytosis or respiratory burst
produce NO (vasodilator)
What are dendritic cells?
phagocytes (& APC’s) w/ dendrites
little arms
what do dendritic cells do after internalising a pathogen
migrate to lymph nodes and activate components of the adaptive immune system
what are lymph nodes
sites around the body contain lymphocytes that are waiting for an immune stimulus
