Block D Lecture 2: Immunity to Pathogens Flashcards
What is a parasite?
An organism which benefits at the expense of another organism (usually of a different species) called a host with the host not benefitting from the association
(Slide 3)
What is one way a host-parasite association may occur?
Due to the host being injured
(Slide 3)
What are 2 examples of unicellular parasites?
Leishmania
Toxoplasma
(Slide 3)
What is leishmaniasis caused by?
Protozoa (unicellular) parasites from over 20 leishmania species
(Slide 4)
What is known to transmit leishmaniasis?
Over 90 species of sandfly
(Slide 4)
What are the 3 main forms of leishmaniasis?
Visceral
Cutaneous
Mucocutaneous
(Slide 4)
What is the fatality rate in untreated cases of visceral leishmaniasis?
> 95%
(Slide 4)
What is the most common form of leishmaniasis?
Cutaneous
(Slide 4)
What 2 things does cutaneous leishmaniasis cause?
Skin lesions and ulcers
(Slide 4)
What is mucocutaneous leishmaniasis?
Partial or total destruction of mucous membranes of the nose, mouth and throat
(Slide 4)
What is crucial in healing cutaneous leishmaniasis?
Cell-mediated immune responses
(Slide 5)
What happens in healing cutaneous leishmaniasis?
Macrophages and dendritic cells produce IL-12 to activate macrophages to kill the parasite
Interferon-gamma from NK cells and Th1 also activate macrophages
The activated macrophages then produce microbicidal (agent that kills microbes) products
(Slide 5)
What happens in Non-healing cutaneous leishmaniasis?
Macrophages are not activated
IL-4 drives a Th2 response instead
Th2 produce IL-4 / IL-13 which inhibit a Th1 response by inhibiting IL-12 production or expression of IL-12Rß2 expression and they also inhibit IFN-gamma production and activity
(Slide 7)
What 2 things are important in healing toxoplamosus?
Cell-mediated immune response and humoral response
(Slide 9)
What is toxoplasmosis caused by?
Toxoplasma parasite
(Slide 9)
What cells can the toxoplasma parasite live in?
Any cell
(Slide 9)
What are the main mediators of toxoplasmosis?
Cytotoxic (CD8+) T cells producing IFN-gamma
(Slide 9)
What role does IgA play in protecting against toxoplasmosis?
Protecting gut mucosa
(Slide 9)
What happens to toxoplasma parasites coated in IgG?
They are killed inside macrophages following phagolysosome fusion
(Slide 9)
What 2 things must the body increase in order to expel gut nematodes?
Increased mucous production
Increased peristalsis (contraction and relaxation of muscles in the gastrointestinal tract)
(Slide 10)