Immunoparasitology Flashcards
Dracunculus medinensis
females lay eggs in water
fleas take them up
when humans get infected (EATS THEM) = very long
need a steady hand to remove them, otherwise if breaks = parasitic GI antigens come out = anaphylactic shock
- wrap worm around stick (SLOWLY) = prevents form pulling back into lesion
Guinea worm
common name for D. medinensis
this worm has a larval stage that penetrates skin while people are drinking from straws
Schistosomaisis
25 human cases of D. medensis in 2016… where?
South Sudan
Chad
Ethiopia
what diseases have we eradicated?
Smallpox
Rinderpest
ability for health professionals to develop vaccines for parasites is very poor
T
public intervention + drugs = main mechanism for controling parasitic diseases
Alberta protozoan parasites
Cryptosporidium
Giardia
Toxoplasma
Amoebiasis
worms/helminths in Alberta
Enterobius
Tapeworms (Hymenolepis, Taenia, Diphullobothrium)
roundworms = Toxoascaris, Trichenella
diet or human to human transmission
T or F. One factor that makes it hard to diagnose parasitic infections is there ability to move around the body
T
lives on the outer surface of host
ectoparasite
obligate parasites
completely dependent on host during part or all of its life cycle (Plasmodium sp.)
facultative parasite
exhibits both parasitic and free living stages as a result, it does not completely depend on host for survival (N. fowleri)
accidental parasit
infects an unnatural host and survives
(Hymenolepis diminuta = rat tapeworm in humans)
erratic parasite
migrates improperly and ends up im host tissues where not usually found
(Trichinella = pork)
direct parasite impacts on host
- mechanical injury to host = migration, growth blockage
- production of toxic substances = waste products, immunologic distraction
- nutrient deprivation = competition for iron, energy, water, etc.
- anemia = consumption or destruction of red blood cells
indirect parasite impacts on the host
- inflammation = resulting form parasite presence or releasd molecules
- encapsulation = granuloma formation
- reduced cognitive capability = stemming from ALL of the above
infection prevalence tends to _______ with age
reduce
- immunolgocial memory?
- but no effective vaccines yet :(
- not always the case for every parasite
T or F. In many cases the immune response is effective at completely clearing parasitic infections
F! not absolutely effective
direct damage cause by parasites is usually ________, damage caused by response to parasites is usually ____________
parasite = minimal
immune system = significant
3 different stages of immune response to parasites
initial exposure
establishment of infection
chonic infection
initial exposure stage of parasites
- usually larval stage of parasites = must arrive safely before infection can begin
- complement important! (parasite = molecules on surface that can activate alternative pathway)
- previous exposure = circulating Abs
- migration of parasites = encounter immune cells
establishment of infection stage parasitic infection
- parasites must implement any immunomodulatory programs it has, but continue to avoid detection
- depending on location in host the parasite may encounter various immune effectors
> tissue: cellular defense, inflammation
> blood: cellular defense, antibody, circulating defense molecules, complement
> gastrointestinal: IgA, antimicrobial peptides, physical environment
chronic infection of parasites
usually immune evasion is working
immune response not capable of completely killing it
early immune cells to parasitic infections
neutrophils and eosinophils
neutrophils mechanism for parasites
- reactive nitrogen/oxygen production
- granules with cytotoxic proteins
> primary: myeloperoxidase, bactericidal/permeability-increasing protein, defensins, elastase
> secondary: alk phosphatase, lysozyme, collagenases
> tertiary
eosinophils mechanism for parasitic infections
- worm infections (parasites too large for phagocytosis)
- degranulate when Fc receptors recognize IgE = enhanced by TNF-a
- act in concert with mast cells due to IgE detection
these hav basal defense capacity that can be engaged before any cytokine production or antibpdy response is generated
tissue macs, monos, granulocytes
what kinds of parasites can phagocytic cells remove?
protozoans and small multicellular parasites
phagocytosis is helpful in causing this which regulates subsequent immune responses
inflammation and cytokine production
this parasite hijacks phagolysosome components by living in them and preventing phagolysosome formation
Leishmania
- prevents infusion of ROS/RNS into phagolysosome
how can phagocytic cells engulf targets many times their size?
recruitment of membrane from the ER and cytoplasmic vesicles
internalizing parasites are important for two reasons
cytokin production & coordination with adaptive immune response
parasitic cytokines
TNFa
IL-1
IL-6
IFNy
besides professional APCs, what other cells can help with parasitic antigen presentation ?
mast cells
eosinophils
basophils
ILC3s
half-life of IgE
2.5 days
(IgG = 23 days)
least common serum antibody
IgE
IgE has a high affinity for the FcE receptors in these cells
mast cells
basos
eos
T or F. IgE binds complement
F! it does not!!!
main function of IgE
immunity to helminth parasites = S. mansoni, T. spiralis, F. hepatica
- also plays a role in protozoans like Plasmodium
Ig isotype associated with allergy and hypersensitivity = anaphylaxis when parasite infection go awry
mast cells
critical for proper defense against helminths
two forms = tissue and mucosal
degranulation = allergic responses; can result in anaphylaxis if primed by high IgE levels specific to antigen
when triggered, mast cells degranulate, producing…
serine proteases
histamine
serotonin
anticoags = heparin
- platelet activating factor
- cytokines
- eosinophil chemotactic factor
= cause extensive swelling, vasodilation, inflammation, pain or itching
ADCC
IgE- independent
- innate effector cells (eos, NK, neuts) recognize antigen-bound Abs on surface of parasite
- recognition of Fc portion of an Ab by a cell-surface Fc receptor to IgG or IgE
= cytokines (IFN-y, cytotoxic granules = perofrin, granzymes) promotes apoptosis in target cell - important for larger helminths too large for phagocytosis
