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Unicellular parasites
Plasmodium – malaria
Giardia lamblia - giardiasis
THE IMMUNE RESPONSES TO PARASITES
L. donovani – Visceral leishmaniasis (Kala azar)L. tropica – Cutaneous leishmaniasis (Oriental sore)L. brasiliensis - Mucocutaneous leishmaniasis (Espundia)
THE IMMUNE RESPONSE TO THE SINGLE CELL PARAZITE LEISHMANIA
Dead parazitesIL-12
TNFIL-2
Th1
Th2
IL-2 IL-10
IL-4
IFNγ
Leishmania major
MACROPHAGE
NO, O2-,H2O2,OH-
CR3CR4
lipophosphoglycane
CLEARS THE INFECTION
DOES NOT CLEAR THE INFECTION
MACROPHAGE
Active radicals
ESCAPE MECHANISMS OF UNICELLULAR PARASITES
Variations in surface structure – gene conversionAlternating expression Trypanosoma
Lysis of phagosome mebraneComplement (DAF) like structures Trypanosoma cruzi
Inhibition of phagosome and lysosome fusion Toxoplasma
Poor antigenicity
Multicellular parasites
Helminths
Tape worm Diphyllobothrium latum9 m in length, lives in small intestineB12 deficiency (magaloblastic anaemia)
Trichinella spiralis „pork worm”
Life cycle of Schistosoma
Schistosoma mansoni Delayed Type Hypersensitivity - DTHFibrosis around the eggs in the liver Chronic inflammation – Fibrotic connective tissueInhibits the venous circulation of the liver
ECFNCF
C'
THE IMMUNE RESPONSE TO MULTICELLULAR WORMS
Can not be ingested by phagocytes
C3a, C5a Monocyte
Neutrophil
Eosinophil
Mast cellIL-3IL-4
Plasma cell IgE
mediators
B
B
Th2
Th2
IL-4, IL-5
LYMPH NODE
IgE IgG
BLOOD
Schistosoma mansoniActivated eosinophils bind to IgE-coated parasites via the low affinity FcεRII
and release their toxic contents onto the wormOther effector cells bind to IgG-coated parasites
Permeability
IgE – MEDIATED CELLULAR CYTOTOXICITY
Shistosoma
Eosinophil granulocyte
IgE
FcεRI
Death of worm
Granules
DEFENSE MECHANISMS AGAINST HELMINTHS
IgE – mediated protection
IgE-mediated antibody dependent cellular cytotoxicity ADCC
EFFECTOR CELLS: mast cells, basophils, and eosinophils
inflammatory mediators
vasodilation recruitment of inflammatory cells fluid outflow
smooth muscle cell contraction mechanical removal
HOST ENVIRONMENT is accepted, resistant to complement and phagocytes
SIZE – no phagocytosis
RESISTANT – to reactive radicals and enzymes of macrophages and
neutrophils
Schistosoma mansoni Delayed Type Hypersensitivity - DTHFibrosis around the eggs in the liver Chronic inflammation – Fibrotic connective tissueInhibits the venous circulation of the liver