Extracellular immunity (year 2)

Question 1

why can’t extracellular pathogens be phagocytosed?

Answer 1

too big

Question 2

why can’t extracellular pathogens be penetrated by complement or T cell perforins?

Answer 2

coat/membrane too thick

Question 3

what is the extracellular immune response driven by?

Answer 3

Th2

Question 4

what are three physiological changes induced by anti-helminth immunity?

Answer 4

increased mucin secretion
increased intestinal mobility
increased water influx into the intestinal lumen

Question 5

what interleukin drives choice towards Th2?

Answer 5

IL4

Question 6

Th2 activates macrophages, but what for?

Answer 6

aid wound repair

Question 7

what cells does Th2 activate?

Answer 7

macrophages
mast cells
eosinophils

Question 8

what immunoglobulins does Th2 promote?

Answer 8

IgG and IgE

Question 9

what do mast cells do in the infection of parasites?

Answer 9

surface has many IgE, antigen binding triggers degranulation releasing enzymes
causes inflammation which stimulates gut motility and mucus secretion which is detrimental to the worms

Question 10

what is the role of eosinophils?

Answer 10

have many IgE molecules on the surface, these bind to the parasite and kills the worm when contents of the eosinophil are released

Question 11

what other ways can antibodies aid the clearance of extracellular infections?

Answer 11

complement mediated lysis
phagocytosis
neutralisation
cell mediated cytotoxicity

Question 12

what ways may helminths evade the immune system?

Answer 12

size
thick extracellular coat
masking antigens by absorbing proteins
molecular mimicry
immunosuppression
enzyme production - cleave antibody 
surface antigen shedding

Question 13

what are the ways antibody may neutralise an extracellular infection?

Answer 13

neutralise toxins
kill bacteria
opsonise bacteria
intracellular killing