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THE IMMUNE RESPONSES TO PARASITES
THE IMMUNE RESPONSES TO PARASITES
Unicellular parasites
Plasmodium – malaria
Giardia lamblia - giardiasis
Life cycle of Leishmania
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 parazites
NO,
IL-12
O2-,H2O2,OH-
IL-2
TNF
Active radicals
CLEARS THE
INFECTION
Th1
MACROPHAGE
IFNγ
lipophosphoglycane
IL-2
IL-10
Leishmania major
CR4
CR3
IL-4
DOES NOT CLEAR
THE INFECTION
Th2
MACROPHAGE
ESCAPE MECHANISMS OF UNICELLULAR PARASITES
Poor antigenicity
Variations in surface structure – gene conversion
Alternating expression Trypanosoma
Lysis of phagosome mebrane
Complement (DAF) like structures
Trypanosoma cruzi
Inhibition of phagosome and lysosome fusion
Toxoplasma
Multicellular parasites
Helminths
Tape worm Diphyllobothrium latum
9 m in length, lives in small intestine
B12 deficiency (magaloblastic anaemia)
Trichinella spiralis „pork worm”
Life cycle of Schistosoma
Schistosoma mansoni
Delayed Type Hypersensitivity - DTH
Fibrosis around the eggs in the liver
Chronic inflammation – Fibrotic connective tissue
Inhibits the venous circulation of the liver
Granuloma in the liver
Hepatosplenomegaly
THE IMMUNE RESPONSE TO MULTICELLULAR WORMS
Can not be ingested by phagocytes
Plasma cell IgE
IL-3
IL-4
mediators
Th2
ECF
NCF
Mast cell
Permeability 
Eosinophil
B
B
IL-4, IL-5
BLOOD
IgE
Neutrophil
IgG
Th2
C'
LYMPH NODE
C3a, C5a
Monocyte
Schistosoma mansoni
Activated eosinophils bind to IgE-coated parasites via the low affinity FcεRII
and release their toxic contents onto the worm
Other effector cells bind to IgG-coated parasites
Schistosoma lárvát támadó eozinofil sejtek
Mast cells
Eozinophils
IgE – MEDIATED CELLULAR CYTOTOXICITY
Death of worm
Shistosoma
IgE
FcεRI
Granules
Eosinophil granulocyte
DEFENSE MECHANISMS AGAINST HELMINTHS
HOST ENVIRONMENT is accepted, resistant to complement and phagocytes
SIZE – no phagocytosis
RESISTANT – to reactive radicals and enzymes of macrophages and
neutrophils
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
Schistosoma mansoni
Delayed Type Hypersensitivity - DTH
Fibrosis around the eggs in the liver
Chronic inflammation – Fibrotic connective tissue
Inhibits the venous circulation of the liver