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Immunology > Innate Immunity - Phagocytosis (5) > Flashcards

Innate Immunity - Phagocytosis (5) Flashcards

1
Q

What is phagocytosis?

A

the ability of some cells to ingest foreign particles
“eating cells”

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2
Q

What are the 2 major types of phagocytes?

A

macrophages
neutrophils

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3
Q

Phagocytes are a class of cells which are capable of ______ and ______ of microorganisms that incite a(n) __________

A

ingestion
killing of microorganisms
inflammatory response

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4
Q

First to accumulate around the invaders and initiate the phagocytic process are _______

A

neutrophils

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5
Q

Later, local and blood-born _______ also migrate to the tissue site and initiate phagocytosis

A

macrophages

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6
Q

Neutrophils and macrophages are sometimes referred to as _______ for their roles in phagocytosis

A

professional phagocytes

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7
Q

Dr. Verma referred neutrophils as “______” and macrophages as “_______”

A

neutrophils: suicide bombers
macrophages: serial killers

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8
Q

What is the sequence of events for phagocytosis?

A

chemotaxis
adherence
ingestion
destruction
egestion - only macrophages
“crown apple is disgusting ew” bro idk

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9
Q

Define chemotaxis

A

delivery of phagocytic cells to the site of infection

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10
Q

What is adherence?

A

phagocytic adherence to the target

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11
Q

What is ingestion?

A

engulfment of the target particle

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12
Q

What is destruction?

A

intracellular killing and digestion of the target

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13
Q

Egestion is only in the case of [neutrophils/macrophages]

A

macrophages

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14
Q

T/F: Phagocytosis occurs within the cytoplasm of a cell

A

FALSE

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15
Q

Opsonization facilitates ______ and ______

A

adherence
ingestion

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16
Q

A neutrophil can phagocytose anything more [hydrophilic/hydrophobic] than itself

A

hydroPHOBIC

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17
Q

What is opsonization? (Hydrophilic or hydrophobic?)

A

coating of a hydrophilic material with opsonins that include
IgG
IgM
C3b

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18
Q

T/F: Neutrophils do not bind hydrophilic material

A

TRUE

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19
Q

Neutrophils cannot phagocytose some bacterial with hydrophilic capsules until they are ________

A

opsonized

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20
Q

What are the neutrophil membrane receptors important in phagocytosis?

A

Fc receptors (“legs”)
C3b receptors (grabbing)

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21
Q

What are Fc receptors?

A

bind antibody that is bound to an antigen
especially IgG antibody

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22
Q

What are C3b receptors?

A

bind to C3b when it is coating bacteria

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23
Q

Once neutrophils bind to opsonized material, it is readily engulfed, forming a ________

A

phagosome

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24
Q

What is a phagosome?

A

a membrane bound vesicle containing the ingested microbe or material

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25
Q

The phagosome migrates into the cytoplasm and collides with _______ which explosively discharge their contents into the phagosome.

A

lysosomal granules

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26
Q

What is a phagolysosome?

A

a digestive vacuole formed form the fusion of a phagosome and lysosome

27
Q

Where is the engulfed microbe killed and digested?

A

within the phagolysosome

28
Q

What are the 3 killing processes to destroy pathogens?

A

lytic enzymes & antimicrobial peptides from granules
oxidative metabolism (respiratory burst)
neutrophil extracellular traps

29
Q

Lytic enzymes and antimicrobial peptides are stored in _______

A

primary granules
secondary granules

30
Q

What are the primary granules of lytic enzymes and antimicrobial peptides?

A

hydrolases
lysozyme
defensins
myeloperoxidase

31
Q

What are hydrolases? Why is it important?

A

breaks covalent bonds by adding water
important for degrading dead bacteria or dead tissues
primary granules

32
Q

What are lysozymes? Where is it found?

A

breaks down peptidoglycan in gram-positive bacteria
found in many secretions in the body
primary & secondary granules

33
Q

What are defensins? They are also called ______

A

small cationic proteins that kill bacteria, especially gram +
have hydrophobic outside and hydrophilic interior
insert into a membrane and form a pore - “punch holes”
antimicrobial peptides
primary granules

34
Q

What is myeloperoxidase?

A

an enzyme that has an important role in the oxygen-mediated killing mechanism
primary granules

35
Q

What are secondary granules of lytic enzymes and microbial peptides?

A

lysozymes
lactoferrin
collagenase

36
Q

What is lactoferrin?

A

chelates iron
bacteria needs iron for survival
secondary granules

37
Q

What is collagenase?

A

degrades connective tissue so it can move through to the site of inflammation
secondary granules

38
Q

What is the most potent killing mechanism of a neutrophil?

A

oxygen-mediated killing mechanism

39
Q

Where does oxygen-mediated killing mechanism occur?

A

phagolysosome

40
Q

What are the killing products of the respiratory burst?

A

hypochlorite
hydrogen peroxide
aldehhydes
oxygen radicals

41
Q

Hypochlorite is an active ingredient in _______

A

bleach

42
Q

What is Chronic Granulomatous Disease?

A

fatal disease caused by a defective oxidative enzyme

43
Q

What are NETs?

A

neutrophil extracellular traps
program for formation of neutrophil extracellular traps (NETs), which consist of modified chromatin decorated with bactericidal proteins from granules and cytoplasm

44
Q

What are NETs stimulated by?

A

CXCL8 or LPS

45
Q

What do NETs release?

A

nuclear material and granular proteins extracellularly (DNA, histones, granular proteins)

46
Q

In NETs, the extracellular degranulation creates a mesh that traps ______, and the ______ kill the protein

A

bacteria
antimicrobial proteins

47
Q

Is NETosis a result of neutrophil death?

A

NO - an active response to inflammatory stimuli

48
Q

What results in pus?

A

neutrophils die and lyse after extended phagocytosis, killing, and digestion of bacterial cells

49
Q

Macrophages egest digested debris and allow insertion of _________ into the plasma membrane for ______ to lymphocytes in the immunological response

A

microbial antigenic components
PRESENTATION (red in the powerpoint, seems important)

50
Q

Macrophages after killing start expressing MHC [I/II]

A

MHC II

51
Q

[M1/M2] cells are for classical activation, and [M1/M2] cells are for alternative activation

A

M1: classical activation
M2: alternative activation

52
Q

Look up important of arginine metabolism in macrophages

A
53
Q

[M1/M2] cells are present when there is chronic infection

A

M2

54
Q

What two things can happen in the removal of dying neutrophils by macrophages?

A

neutrophil can either “shake hand” with CD31 and have neutrophil surival or
neutrophil fails to reply to CD31 and phagocytosis of neutrophil occurs

55
Q

Cytokines activate _______ cells so that neutrophils in the bloodstream will, stop, attach, and then migrate toward sites of _________

A

vascular endothelial cells
microbial invasion and tissue invasion

56
Q

_______ must usually be opsonized before they can be efficiently ingested and killed

A

Microorganisms

57
Q

The most effective opsonins are ______ and _______

A

antibodies
complement

58
Q

What is the respiratory burst? It is done by what proteins?

A

ingested microorganisms are killed by potent oxidants
done by antibacterial proteins called defensins and by lytic enzymes

59
Q

T/F: Neutrophils are short-lived cells that cannot undertake prolonged or multiple phagocytosis

A

TRUE

60
Q

[Neutrophils/Macrophages] migrate to sites of inflammation secondarily. They eat and kill _______

A

Macrophages
eat and kill any surviving microbial invaders, neutrophils

61
Q

Macrophages eat dead and dying neutrophils and thus prevent _______

A

damage caused by escaping neutrophil enzymes

62
Q

_______ begin the healing process in damaged tissues

A

Macrophages

63
Q

[Neutrophils/Macrophages] are essential antigen-presenting cells for the adaptive immune system

A

Macrophages

Immunology (36 decks)

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