mucosal immunity L25 Flashcards
how to stop T and B cells from responding to food
food is full of antigens that are non-self
central tolerance can delete self-reactive T cells but not ones that recognise non dangerous antigens on foo
but food will not cause damage, so no B7 (signal 2) present on APC or DC cells so no second signal to activate Th cell
oral tolerance
soluble antigens like ones on food given orally causes the immune system to become tolerant to that antigen
on subsequent ingestion the immune system won’t mount an effect response
peripheral tolerance like this can be considered immune memory
anergy
No signal 2 so T cell lives but becomes non responsive
celiac disease
in response to gluten
has an increase in Th1 cells producing more IFN-Y
so more macrophage and B cells activated
food allergies
when consumed
more Th2 cells , so more IL-4
so more mast cells, B cells producing IgE, more histamines
IgA is the predominant antibody response in intestine
the one with least amount of inflammatory response
IgA mucosal specialisation
the dimeric structure makes it good at clumping together and neutralising pathogens
and IgA is poor at stimulating ADCC so doesn’t cause a strong inflammatory response, least amount of damage to epithelial barrier
mucosal immunity and passive approach
mucosal immunity blocks or pushes microbes away from epithelium instead of stimulating a strong response to try and kill
tight junctions - mucosal immunity
this prevents epithelium penetration of microbes so cannot get in
mucus layer - mucosal immunity
this prevents microbes getting into epithelium and traps them
anti-microbial peptides - mucosal immunity
this is in the inner mucus layer, damage microbes that get too close to the epithelium
IgA - mucosal immunity
specialised for neutralising and blocking microbes
commensal microbiota benefits
detoxification benefits
biosynthetic benefits
immune maturation
metabolic benefits
excludes pathogens - outcompetes
without commensals, the immune system does not develop
commensals can still be dangerous
they are adaptive to have lower virulence, like not having factors that allow penetration to gut epithelium
but if given the chance, can be opportunistic
appendicitis
this occurs when the appendix gets blocked and builds up of mucus and intestinal/microbial products cause inflammation and dropping of barrier integrity
this allows commensals to invade, leading to burst
immune regulation
regulatory T cells can secreted IL-10 which inhibit Th cells, B cells, macrophage activation, DC, APC and the production of TNF-A IFN-Y IL-4
also Treg can inhibit in an Ag specific manner and interact with APC via MHC 2 to also cause the same inhibitions
