11/8/12 Flashcards Preview

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Flashcards in 11/8/12 Deck (21):
1

what types of pathogens are intracellular?

viruses
some bacteria and protozoa

2

what is main defense against intracellular pathogens?

cytotoxic t lymphocytes
NK cells

3

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

activating receptor = NKG2D. Recognize MIC

inhibitory receptors on cell surface - recognize MHC I receptor

4

what is the main defense against extracellular pathogens?

complement
Ig secretion
helper T cells

5

what cell type activates macrophage to kill organisms ingested?

Th1

6

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

binds MHCII and becomes activated

upregulates CD40 and produces IFNgamma

activates production of ROS in phagocyte endosomes

7

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

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

activate macrophages via Fc receptors

8

what is the response to helminth infections?

Th2 responds

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

cytokines stimulate eosinophils

9

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

increase turnover helps shed parasitized cell

mucus prevents adherence and accelerates loss of parasite

10

how do eosinophils get activated and respond to helminth infection?

IL-4 promotes IgE production by B cells

IgE targets helminth

eosinophils become cytotoxic

11

General mechanism of type I hypersensitivity?

similar to anti-helminth response

12

general mechanism of type II

involves antibodies binding to surface-linked antigens.

13

general mechanism of type III

antibodies binding to soluble antigens

14

general mechanism of type IV

depends on activation of antigen-specific T cells

15

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

immunosurveillance

16

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

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

17

how do innate lymphocyts recognize tumor cell?

increased MIC expression on tumor cell

NGK2d receptor on NK or gammadelta cell activate cytotoxicity

18

In general, how do tumor cells avoid immunosurveillance?

those cells that mutate and have way to evade win out

19

what are the two main ways tumor cells avoid immunosurveillance?

immune evasion

20

how does immune evasion work and give example

loss of expression of things that killer cells recognize

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

21

how does immune suppression work?

produce suppressing cytokines that inhibit cytotoxic and Th1 responses

and/or enhance regulatory response by immune system