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Flashcards in 2 phagocytosis Deck (41):
1

phagocyte

ingest particles through zipper model, receptor driven

2

kinds of phagocytes

neutrophils
macrophages/monocytes
eosinophils
basophils
dendritic cells
microglial cells
osteoclasts

3

monocytes

circulate in the bloodstream

4

dendritic cells

present class II (humoral + T cell response)

5

macrophages

1 long lived
2 present in tissues (when mature)
3 02 dependent killing not vigorous
4 conditions amenable for intracellular growth of pathogens
5 pathogen tactics in battle

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macrophage pathogen tactics in battle

1 circumvent respiratory burst
2 break out of phagosome
3 prevent phagolysosome fusion
4 resist granule contents

7

polymorphs

1 short lived
2 circulating
3 respond to conditions stimulating inflammation, leaving circulation
4 vigorous respiratory burst during phagocytosis
5 extremely hostile environment
6pathogen tactics

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pathogen tactics of polymorphs

-resist phagocytes
-kill or be killed

9

receptors on phagocytes

phagocytic receptors, adhesion receptors, activation receptors, MHC class I and II

10

phagocytic receptors

integrins and complement receptors + lectins + Fc receptors

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3 roles for complement components

bacteria lysis
phagocytic chemotaxis
bacteria opsonizatoin

12

Fc receptor

if you are immune to an organism, phagocytes can still recognize with their Fc receptors
-Fc receptors recognize the constant region of IgG
- Fc receptors help internalize the microorganism and degrade it

13

2 receptor classes

immune + nonimmune

14

opsonization

recognition by specific receptors, convenient way to limit the number of receptors on surface of phagocytic cells

15

lectin

receptors on phagocytes can also recognize yeast; they can recognize carbs on yeast cells

16

in absence of acquired immunity

c3bi and complement receptors

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in presence of acquired immunity

igG, opson, Fc receptors

18

lectin

direct recognition of specific cabs
-a specific receptor

19

dectins

major class of phagocyte lectins is involved in recognition of fungal pathogens

20

activation receptors

toll like receptors, IL-1 receptor, TNF receptor, IFN gamma receptor

21

toll like receptors

recognize nuclei acids, LPS, lipoproteins specific for microorganisms

22

IL-1 receptor

mediator of inflammation

23

iFN gamma receptor

classical way where phagocytes get activated, associated with inflammatory response

24

early classical activation

1 inflammation
2 bacterial and viral diseases

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later alternative actiavation

noninflammatory
clears tissue damage
often less restrictive of pathogens

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properties of classically activated phagocyte

1 enhanced rate of phagocytosis
2 enhanced production of toxic reactive oxygen intermediates (antimicrobial)
3 enhanced production of NOI (nitric oxide; antimicrobial)
4 enhanced phagosome-lysosome fusion
5 increased number of MHC class II molecules
6 secretion of IL-12: differentiation of CD4 T cells

27

transendothelial migration

1 endothelium becomes activated and has receptors for the neutrophils
2 rolling= maing and breaking of contact bewteen phagocytic cell and endothelium
3 increased production of inflammatory mediators
4 phagocyte is mobilized and can transmigrate

28

antimicrobial activity begins

-before the microbe is completely engulfed
-primary mode of killing prior to engulfment is the oxidative burst, in which toxic oxygen free radicals are produced

29

NADPH oxidase assembly in response to microbial adhesion

most important generator of oxygen free radicals is the NADPH oxidase complex

30

mechanism II

suicide by NADPH oxidase release antimicrobial "NETS"

31

histones associated with NETS are

antimicrobial

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microorganisms get trapped by

these nets and get killed

33

live neutrophils will elicit

oxygen free radicals that will kill organisms that will also kill neutrophils
-neutrophil death willliberate nuclei acid that will create a net

34

if microorganisms are internalized

oxygen independent organisms are used instead

35

killing mechanism III

antimicrobial peptides: defensins and cathelicidins
-proteins inject themselves into the envelope of microorganisms and cause disruption of the envelope so that the microorganisms depolarize and kill

36

defensins

pair of beta sheets

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cathelicidins

helical

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tactics used by pathogens to avoid killing by phagocytes

1 kill or be killed (cytotoxicity)
2 inhibit opsonization or inactivate phagocytosis
3 survive intracellular killing

39

pathogens avoid phagocytes by: killing or being killed (cytotoxicity)

-streptococcous streptolysi O
-bordetella pertussis adenylate cyclase

40

pathogens avoid phagocytes by: inhibit opsonization of inactivate phagocytosis

1. capsule: s. pneumoniae
2. M protein: S. pyogenes
3. disrupt signaling: RhoGAP proteins

41

pathogens avoid phagocytes by: survive intracellular killing

1 inhibit phagosome-lysosome fusion: M. Tb
2 escape from phagosome: Rickettsia
3. survive lysosomal enzymes: Salmonella