III - parasites Flashcards
definition of ectoparasites
parasites that live on the outside of the host
either on the skin or outgrowths of the skin
difference between CD4 Th1/2 cells
Th1 - intracellular infective agent, micro-endoparasites (macrophage driven)
Th2 - extracellular infective agents, macro-endoparasites (eosinophil driven)
what do macrophages/dendrocytes release and what does it target
IL-12
NK cells
naive T cells
Th1 cells
what do NK cells and Th1 cells release in response to IL-12 and what does it do
releases IFN-γ
activates macrophages
causes naive T cells to preferentially become Th1 cells
what do activated macrophages release
pro-inflammatory cytokines
IL-1
IL-6
TNF-α
what causes IL-12 activation in Th1/NK cells
stimulation of TLR eg.
TLR2 binds GPI
TLR9 binds parasitic dsDNA
what do a percentage of IL-12/IFN-γ induced Th1 cells activate
protozoal specific B cells
preferentially induce IgG2/IgG3 expression in B cells
in general there is MHCII activation, what does this mean
innate and inflammatory NK/macrophages are the main ones being expanded
what do macro-parasites activate
eosinophils
basophils
what do helminths induce
Th2 response via IL-4
during a macroparasitic infection, what is the purpose of the release of IL-10 and TGFβ from Th2
limit acute inflammation via macrophages
during a macroparisitic infection, what cells are prioritised to be activated
eosinophils
basophils
what is the main antibody response in a macroparisitic infection
IgE
mice - IgG1
humans - IgG4
what is the IgE concentration of the total Ig serum
0.05%
what is the high-affinity IgE receptor
FcεRI
inducible in eosinophils
expressed on mast cells and basophils
when happens when an antigen binds to IgE bound to FcεRI cells
causes cross-linking of the bound IgE
aggregation of FcεRI
degranulation and release of mediators from the cell
what is the low affinity receptor that binds IgE
CD23/ FcεRII
function of CD23/FcεRII
regulation of IgE levels
present on eosinophils, mature B cells, macrophages
what are eosinophils
small granules which contain chemical mediators
what do eosinophils contain
eosinophil peroxidase
deoxy/ribonucleases
lipase
major basic proteins
what are pre-formed mediators basophils release when activated
histamine
serotonin
heparin
what are the newly formed lipid mediators released by basophils when activated
prostaglandin D2
leukotriene C4
platelet-activating factor
what are the newly formed cytokines released by basophils when activated
eosinophil chemotactic factor
interleukin-4
what is a main function of interleukin-4
critical cytokine in production of IgE
how does filariasis larvae use the response to insect bite to its advantage
mast cell degranulation after bite causes vasodilation
increased vascular permeability
larvae can move readily into bloodstream
the L3 nematode is a weak point for the larvae, how does it increase its chances of survival
produce proteins to block TLR’s
inhibit TCR signalling
promote Treg cells to dampen immune response
how does L3 nematode larvae inhibit TCR signalling
ES-62 tetrameric glycoprotein attached to phospholipids
taken into host T cell
inhibits PKC pathway that TCR’s induce
how does L3 modify the immune response
IL10 mediated class switch to IgG4
no complement activation
no ADCC activity
how does the class switch to IgG4 improve survival chances for L3
IgG4 binds Fcε
blocks IgE
no basophil/eosinophil degranulation
lowers IL4/IgE formative cycle
what are the 3 main ways leishmaniosis presents
cutaneous
mucocutaneous
visceral
