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Question 1

what types of pathogens are intracellular?

Answer 1

viruses

some bacteria and protozoa

Question 2

what is main defense against intracellular pathogens?

Answer 2

cytotoxic t lymphocytes

NK cells

Question 3

what receptors are on NK cell surface and what stimulates them?

Answer 3

activating receptor = NKG2D. Recognize MIC

inhibitory receptors on cell surface - recognize MHC I receptor

Question 4

what is the main defense against extracellular pathogens?

Answer 4

complement
Ig secretion
helper T cells

Question 5

what cell type activates macrophage to kill organisms ingested?

Answer 5

Th1

Question 6

how do Th1 cells enhance killing of organisms ingested by phagocytes?

Answer 6

binds MHCII and becomes activated

upregulates CD40 and produces IFNgamma

activates production of ROS in phagocyte endosomes

Question 7

how do Th1 and Th2 and B cells facilitate pathogen uptake and breakdown in macrophages?

Answer 7

Th1 and Th2 help B cells produce high affinity Abs that facilitate pathogen uptake

activate macrophages via Fc receptors

Question 8

what is the response to helminth infections?

Answer 8

Th2 responds

produces IL-4, IL-13 which are recognized by epithelial cells on mucosal surface

cytokines stimulate eosinophils

Question 9

what is the mucosal cell response to IL-4 and IL-13 in helminth infection?

Answer 9

increase turnover helps shed parasitized cell

mucus prevents adherence and accelerates loss of parasite

Question 10

how do eosinophils get activated and respond to helminth infection?

Answer 10

IL-4 promotes IgE production by B cells

IgE targets helminth

eosinophils become cytotoxic

Question 11

General mechanism of type I hypersensitivity?

Answer 11

similar to anti-helminth response

Question 12

general mechanism of type II

Answer 12

involves antibodies binding to surface-linked antigens.

Question 13

general mechanism of type III

Answer 13

antibodies binding to soluble antigens

Question 14

general mechanism of type IV

Answer 14

depends on activation of antigen-specific T cells

Question 15

what is the most effective anti-tumor function of the immune system?

Answer 15

immunosurveillance

Question 16

what types of antigens would a tumor cell present to CTLs triggering their activation?

Answer 16

1. presention of mutant peptide from mutated cellular protein
2. reactivation of embryonic genes not normally expressed in differentiated cell
3. overexpression of normal self protein changing density of self-peptide presentation

Question 17

how do innate lymphocyts recognize tumor cell?

Answer 17

increased MIC expression on tumor cell

NGK2d receptor on NK or gammadelta cell activate cytotoxicity

Question 18

In general, how do tumor cells avoid immunosurveillance?

Answer 18

those cells that mutate and have way to evade win out

Question 19

what are the two main ways tumor cells avoid immunosurveillance?

Answer 19

immune evasion

Question 20

how does immune evasion work and give example

Answer 20

loss of expression of things that killer cells recognize

i.e. variant tumor cell cleaves MIC (becomes soluble) or blocks expression of MIC

Question 21

how does immune suppression work?

Answer 21

produce suppressing cytokines that inhibit cytotoxic and Th1 responses

and/or enhance regulatory response by immune system