Immunology: Late Innate Immune Responses Flashcards
what are PAMPS
- pathogen-associated molecular patterns
- found on antigens
what are PRRs
- pattern recognition receptors
- found on innate immune cells cell membrane and detect IC/EC pathogens
when the complement system is activated what does it promote
- acute inflammation
- pathogen killing
- pathogen opsonisation
- leukocyte recruitment
draw the diagram of complement system activation
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how is MAC formed and what does it do
- C5b associates with another protein to form pore channels
- this allows salt and water into the pathogen causing it to swell and burst
what complement protein is a good opsonin
C3b
what complement proteins are anaphylatoxins
C3a and C5a
what do anaphylatoxins do
- promote local inflammation and leukocyte recruitment by activating mast cell
- act directly on local bv to produce vascular changes
what vascular changes does acute inflammation promote
- loss of endothelial tight junctions
- post-capillary vasocilation
- increased permeability
- endothelial expression of adhesion molecules
what cellular changes occur during acute inflammation
- neutrophils are recruited and activated, adhesion molecules expressed, transendothelial migration
- monocytes recruited
describe transendothelial migration
- neutrophil margination and inflammatory sites
- neutrophils bind to adhesion molecules
- migration across endothelium by diapedesis
- chemotaxis transport neutrophils in tissues
- PAMPs and TNF-alpha activate neutrophils
how do neutrophils pahgocytose pathogens
- phagolysosomal killing
- ROS, respiratory burst, ROS produced and release into phagosome (H202)
how do neutrophils kill pathogens (3)
- phagocytosis
- degranulation
- NETs
describe neutrophil degranulation
anti-bacterial proteins release into ECF killing pathogens
what is the downfall to neutrophillic degranulation
can cause tissue damage and potentially systemic inflammation
when does neutrophillic degranulation occur
after phagocytosis to kill all nearby EC pathogens
describe pathogen killing via NETs
- NETs composed of DNA, proteins and enzymes are release from the cell
- this immobilised the pathogen to prevent spreading but also aids phagocytosis
- minimum host damage but kills cell
what drives and mediates the acute phase response
- pro-inflammatory mediatoirs drive
- mediated by liver hepatocytes producing acute phase proteins
acute phase proteins
- C3 and MBL - complement
- CRP - opsonin
what do virally infected cells release
interferons
what do interferons do
- interfere with viruses ability to replicate within host cells and therefore prevent viral replication
- signal to cells to produce anti-viral factors that interfere with viral replication and protect the cell
- signals to other cells that a virus is present
when neraby cells recieve signal of a viral presence what happens
they produce MHC 1 and surveying T cells identify and eliminate the virus
what os the role of NK cells
recognise and destroy virally-infected and cancer cells
what happens to NK cells during acute inflammation
recruited to site of inflammation and are longer lived than neutrophils
