Innate Immunity Cont. Flashcards
What can perform phagocytosis?
neutrophils, dendritic cells, macrophages
What is phagocytisis?
the uptake and degradation of extracellular material
Steps of phagocytosis
=
How is phagocytosis initiated?
2 ways
- PAMP recognition by a PRR
- opsonins
Do all PRRs initiate phagocytosis?
no
How do opsonins initiate phagocytosis?
- bind to microbes and mark them for phagocytosis
- bind to receptor on phagocytic cell which then initiates phagocytosis
What is microbe degradation?
when the phagosome fuses with the lysosome, the contents of lysosome act to kill and degrade the pathogen
What ways does microbial degradation occur?
- antimicrobial proteins
- low pH
- enzymes
- molecules that mediate oxidative attack
What antimicrobial proteins do microbial degradation?
lysozyme and defensins
How does low pH do microbial degradation?
kills pathogen, activates enzymes
What enzymes do microbe degradation?
proteases
What does proteases do?
degrade protein
What molecules mediate oxidative attack?
- reactive oxygen species (ROS)
- reactive nitrogen species
What is an example of a reactive oxygen species?
hydrogen peroxide (H2O2)
What is an example of reactive nitrogen species?
nitric oxide (NO)
Steps of NETs
-
What does NETs stand for?
neutrophil extracellular traps
What do NETs do?
trap pathogens
How do NETs trap pathogens?
contain antimicrobial proteins from cytoplasmic granules that kill the trapped pathogens
What is the process using NETs called?
NETosis
What happens to the neutrophil as a result of NETosis?
neutrophil dies
What does inflammation result from?
cellular response and tissue damage due to pathogens getting through the physical barriers of innate immune system
What are characteristics of the inflammatory response?
- pain
- redness
- heat
- swelling
- loss of function
What causes heat and reddness?
reflect an increase in vascular diameter which increases blood flow to area
What causes swelling?
reflect an increase in vascular permeability causing cells and fluid to leave blood
What causes pain?
damage to nerves as result of inflammation response
What causes a loss of function?
all other symptoms
Steps of inflammatory response
-
What is the acute phase response?
the phase preceding either recovery or death
What does the acute phase response result in?
systematic changes in body
What are the systematic effects of the acute phase response?
- sickness behaviors
What are sickness behaviors as result of acute phase response caused by?
proinflammatory cytokines acting on brainW
What are the sickness behaviors?
- fever
- loss of appetite
- lethargy
- body aches
What causes a fever in terms of acute phase response?
- COX2 activated to produce prostaglandins that increase body temps through shivering
What is the purpose of a fever?
increase chemotaxis and immune cell survival
What causes a loss of appetite in terms of acute phase response?
proinflammatory cytokines act on hunger centers in the brain to decrease appetite
What causes lethargy in terms of acute phase response?
proinflammatory cytokines act on sleep centers in brain to cause animal to be tired
What causes body aches in terms of acute phase response?
proinflammatory cytokines act on nerves to cause body aches
What are other acute phase effects?
- increased hematopoiesis of white blood cells
- increased skeletal muscle protein catabolism
- production of acute phase proteins in liver
- liver produces lipocalin-2
- liver produces hepcidin
What does increased hematopoiesis of white blood cells mean?
replenishes immune cells in blood
What does increased skeletal muscle protein catabolism mean?
protein of skeletal muscle gets broken down, releases amino acids from proteins
What kind of acute phase proteins are produced in liver?
Fe binding proteins
What are the Fe binding proteins produced in liver as result of acute phase?
transferrin and haptoglobin
What do transferrin and haptoglobin do?
bind Fe and make it unavailable to bacteria
What does bacteria produce?
siderophores
What do siderophores do?
compete with transferrin and haptoglobin to bind Fe and can remove Fe from them
What does lipcalin-2 do?
binds siderophores to keep them from binding to Fe
What does hepcidin do?
keep Fe from being released from hemoglobin
What two types of receptors do natural killer cells have to detect abnormal/infected cells?
- inhibitory and activating
What do inhibitory receptors on NK cells recognize?
MHC class one
What happens when MHC 1 binds to inhibitory receptor?
signal to NK cells to NOT kill the cell
What do activating receptors on NK cells recognize?
ligands upregulated on infected cells
What happens when ligands bind to activating receptors?
signals the NK cell to kill the infected cell
How do NK cells kill infected cells?
2 ways
- FasL on NK cell binds to Fas on infected cell which initiates apoptosis on infected cell
- NK cells secrete perforin and granzyme
What does perforin do?
punctures holes in cell membrane of infected cell
What does granzyme do?
enters cell through holes and initiates apoptosis of infected cell
