Exam 2- Immunity to Extracellular Pathogens

Question 1

true/false: the humoral immune response is the main protective response against extracellular pathogens

Answer 1

true

Question 2

what two things can act as opsonins when they bind to the surface of a microbe?

Answer 2

antibodies and C3b

Question 3

what is African Trypanosomiasis?

Answer 3

disease of African trypanosomes: flagellated parasitic protozoans that live in the bloodstream of several host species

Question 4

what allows some parasites to escape the humoral immune response?

Answer 4

they have different variant surface glycoproteins (VSGs)
VSGs are what the response develops to

Question 5

does an individual trypanosome have one VSG gene, a few, or many?

Answer 5

many, only expresses one at a time

Question 6

why are cape buffalo able to keep parasite levels low, without having multiple parasitemia waves?

Answer 6

able to have chronic cryptic infection
develop trypanocidal activity in serum: xanthine oxidase generates reactive oxygen species that kill the parasites
antibodies against non-VSG molecules are generated: inhibit growth

Question 7

what is a part of human protein that can mediate trypanosome killing?

Answer 7

apolipoprotein L-1

Question 8

what are helminthiases caused by?

Answer 8

nematoda and platyhelminthes mostly

Question 9

true/false: nematoda and platyhelminthes are always extracellular and can be in multiple places in the host (not just bloodstream)

Answer 9

true

Question 10

what do T helper 2 cells (Th2) induce?

Answer 10

IL-4, IL-5, IL-13
high amounts IgE (induces class switching)
stimulates growth mast cells

Question 11

what type of immune response do schistosomes elicit?

Answer 11

robust Th2 immune response

Question 12

what are the components of the Th2 response against schistosomes (blood flukes)?

Answer 12

degranulation of mast cells brings eosinophils and macrophages
these express Fc receptors for IgE and IgG and may bind to antibody-coated parasites
eosinophil can participate in antibody-dependent cell-mediated cytotoxicity once bound

Question 13

true/false: schistosomes survive for years in the vasculature of immuno-competent hosts

Answer 13

true

Question 14

true/false: it is proposed that schistosomes inhibit the formation of membrane attack complexes that could damage or destroy they outer membranes

Answer 14

true

Question 15

true/false: schistosome evade being destroyed through their eggs, which are not attacked in the body

Answer 15

false; eggs are attacked if do not make it to the exterior and are instead in the liver or other internal organs

Question 16

how do granulomas function with schistosome eggs?

Answer 16

sequester eggs away so that liver can continue to function

Question 17

true/false: the ability of the host to physically expel gastrointestinal nematodes is not linked to their ability to mount a Th2 response against the parasites

Answer 17

false; closely linked

Question 18

how is gastrointestinal worm expulsion achieved?

Answer 18

Th2 cytokines act on mast cells, non-lymphoid epithelial cells, and goblet cells to create an inhospitable environment

Question 19

true/false: nematoda and platyhelminthes occupy multiple niches in mammalian hosts

Answer 19

true

Question 20

do helminths multiply within their hosts?

Answer 20

no

Question 21

what comprises the immune response to parasitic helminthes?

Answer 21

high IgE
strong eosinophil and mast cell responses

Question 22

what cytokines are produced in response to parasitic helminthes?

Answer 22

IL-4, IL-5, IL-13

Question 23

how does the body react to schistosomes?

Answer 23

robust Th2 response
degranulation mast cells leads to eosinophils and macrophages: Fc receptors for IgE and IgG

Question 24

what do eosinophils release with parasites?

Answer 24

basic protein and other mediators
ADCC

Question 25

when schistosome eggs end up in the liver, what cytokines are important for protecting the host?

Answer 25

Th2 cytokines: IL-13 leads to fibrosis, IL-4 important