Innate immunity Flashcards
What does the immune system identify and eliminate
microorganisms
cancer cells
What does the immune system identify in order to activate?
danger signals
‘non-self’ molecules
What are the factors of the innate immune response
natural/physical barriers
immune cells
What are the soluble factors of the innate immune response
cytokines
inflammatory mediators
complement proteins
What cells are part of the innate immune response
macrophages
mast cells
natural killer cells
neutrophils
What soluble factors are part of the acquired immune response
cytokines
antibodies
what cells are part of the acquired immune response
B cells
T cells
What are the points of entry for pathogens
digestive system
respiratory system
urogenital system
skin damage
What are the types of barriers in the immune response
physical
secretions - mucous
expelling through sneezing
unfavourable pH
enzymes
comensal bacteria
What is the timescale for an innate immune response
rapid (mins-hours)
What is the timescale for an acquired immune response
slow - days
What are the key qualities of innate immunity
continuous
from birth
generic response to many species
what are the key qualities of acquired immunity
induced by presence of foreign materials
unique response to individual pathogens
What are the key differences between innate and acquired immunity
lag time
immunological memory
specific/generic
self regulated
What are the types of phagocytic cells
macrophages
dendritic cells
What are PAMPS
pathogen associated molecular patterns
not found in/on human cells
What is phagocytosis
intact particles (bacteria) are internalised whole
How is phagocytosis facilitated
opsonisation
What are PRRs
pathogen recognition receptors expressed by macrophages
What occurs after fusion occurs to form a phagolysosome and its contents are degraded
debris is released
peptides from pathogens are expressed on cell surface receptors
pro-inflammatory mediators are released
What is opsonisation
bacterium is coated in opsonins which bind to receptor on phagosome causing it to be engulfed
what are examples of opsonins in innate immunity
C3b
C-reactive protein (CRP)
What cell type kills cells too large to be engulfed
mast cells
What do mast cells contain in their granules
anti-microbial substances
inflammatory substances
What is the con of degranulation of a mast cell
can damage by standing tissues
What is an example of a pro-inflammatory cytokine
TNF-alpha
What are the signs of acute inflammation caused by TNFa
dilation of blood vessels
increased permeability of post-capillary venules
stimulated nerve ending
What does inflammation promote
vascular changes
recruitment/activation of neutrophils
how are neutrophils attracted to the site of inflammation
chemicals produced by bacteria
What are the 3 killing methods of neutrophils
phagocytosis
degranulation
NET’s (vomit)
How are internalised pathogens killed
phagolysosomal killing
ROS-dependent
How does phagolysosomal killing occur
phagosome fuses with azurophillic and specific granules
pH is raised
How does ROS-dependant killing mechanism work
Toxic reactive-oxygen-species is released into the phagolysome
How does degranulation kill bacteria
Release of anti-bacterial proteins from neutrophil granules
What method is used to kill extra-cellar pathogens
degranulation
How does Neutrophil Extracellular Traps (NETs) kill bacteria
Sticky web of proteins and genetic info
traps pathogens to be engulfed by another cell
Which cell type is best for wound healing and anti-inflammation
macrophages
which phagocytic cell is the best for antigen presentation
dendritic
What are the clinical features of acute inflammation
fever
increased synthesis of acute phase proteins
increased synthesis of neutrophils
Where are acute phase proteins produced
liver hepatocytes
What are the compliment system proteins
C3
MBL
what cytokine is produced by virally infected cells
interferons
what results from the binding of interferons
destroy RNA
reduce protein synthesis in cell
induce apoptosis
activate natural killer cells
How do natural killers cell know which cell to kill
Inhibitory receptor scans cell for MHC 1 which cancer cells/infected cells do not express