Lecture 5 - Phagocytosis

Question 1

What is phagocytosis

Answer 1

ability of some cells to ingest foreign particles

Question 2

What are phagocytes

Answer 2

class of cells which are capable of ingestion and
killing of microorganisms that incite inflammatory response

Question 3

What cells are the first to accumulate around invaders and initiate phagocytosis

Answer 3

neutrophils

Question 4

What are the second cells to migrate to the tissue site and intiate phagocytosis

Answer 4

local and blood-borne macrophages

Question 5

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

Answer 5

professional phagocytes

Question 6

What are the 2 professional phagocytes

Answer 6

neutrophils and macrophages

Question 7

What are the 4 steps of phagocytosis

Answer 7

1. chemotaxis
2. adherance
3. ingestion
4. destruction

Question 8

What is chemotaxis (in regards to phagocytosis)

Answer 8

delivery of phagocytic cells to the infection site

Question 9

What is adherance (in regards to phagocytosis)

Answer 9

phagocytic adherance to the target

Question 10

What is ingestion (in regards to phagocytosis)

Answer 10

engulfment of the target particle

Question 11

What is destruction (in regards to phagocytosis)

Answer 11

intracellular killing and digestion of the target

Question 12

What part of phagocytosis is only in the case of macrophages

Answer 12

egestion

Question 13

What can neutrophils phagocytose

Answer 13

anything more HYDROPHOBIC than itself

Question 14

What is opsonization

Answer 14

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

Question 15

What happens after opsonization of a hydrophilic substance

Answer 15

allows neutrophils to bind it

Question 16

What bacteria can neutrophils NOT phagocytose until they are opsonized

Answer 16

bacteria with HYDROPHILIC capsules (Staphylococcus, Streptococcus, Klebsiella)

Question 17

Why are mycobacteria sp. easily phagocytosed by neutrophils

Answer 17

have hydrophobic capsules

Question 18

What 2 neutrophil membrane receptors are important for phagocytosis

Answer 18

Fc and C3b

Question 19

What do Fc receptors bind

Answer 19

antibody that is bound to an antigen, especially IgG antibody

Question 20

What do C3b receptors bind

Answer 20

to C3b when it is coating bacteria, ect.

Question 21

What happens once neutrophils bind to opsonized material

Answer 21

it is readily engulfed, forming phagosome

Question 22

What is a phagosome

Answer 22

membrane bound vesicle containing the ingested microbe or material

Question 23

What happens when a phagosome migrates into the cytoplasm and collides with lysosomal granules

Answer 23

lysosomal granules explosively discharge their contents into the membrane-enclosed vesicle (phagosome)

Question 24

What is formed when membranes of the phagosome and lysosome fuse

Answer 24

digestive vacuole called phagolysosome

Question 25

What can fuse with the phagolysosomes

Answer 25

other lysosomes

Question 26

What occurs within the phagolysosome

Answer 26

killing and digesting of the engulfed microbe

Question 27

What does it mean when the killing process is confined to the phagolysosome?

Answer 27

none of the toxic substances and lethal activities of the phagocytes are turned against themselves

Question 28

What is the first detectable effect on bacterial physiology after phagolysosome formation; and how fast does it occur after engulfment

Answer 28

loss of viability; within a few minutes

Question 29

What happens 10-30 minutes after ingestion

Answer 29

many pathogenic and nonpathogenic bacteria are killed followed by lysis and digestion of the bacteria by lysosomal enzymes

Question 30

What are the 3 killing processes

Answer 30

1. lytic enzymes and antimicrobial peptides from granules 2. oxidative metabolism (respiratory burst) 3. neutrophil extracellular traps

Question 31

What are stored in primary and secondary granules

Answer 31

lytic enzyme and antimicrobila peptides

Question 32

Where are lytic enzymes and antimicrobial peptides stored

Answer 32

primary and secondary granules

Question 33

What are the 4 primary granules?

Answer 33

1. hydrolases 2. lysozyme 3. defensins 4. myeloperoxidase

Question 34

What are hydrolases

Answer 34

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

Question 35

What are lysozymes

Answer 35

breaks down peptidoglycan in Gram-positive bacteria. Found in many secretions in the body

Question 36

What are defensins

Answer 36

small cationic proteins that kill bacteria, especially Gram-positive bacteria; 29-42 amino acids long; hydrophobic outside and hydrophilic interior and insert into a membrane and form a pore

Question 37

What is another name for defensins

Answer 37

antimicrobial peptides

Question 38

What is a myeloperoxidase

Answer 38

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

Question 39

What are the 3 secondayr granules

Answer 39

1. lysozymes 2. lactoferrin 3. collagenase

Question 40

What is lactoferrin

Answer 40

chelates iron- bacteria need iron for survival

Question 41

What is collagenase

Answer 41

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

Question 42

What is the most potent killing mechanism of a neutrophil

Answer 42

oxygen mediated killing mechanism

Question 43

Where does oxygen mediated killing occur

Answer 43

phagolysosome

Question 44

What are the killing products of the respiratory burst

Answer 44

1. hypochlorite 2. hydrogen peroxide 3. aldehydes 4. oxygen radicals (superoxide anion and hydroxyl radical)

Question 45

What s chronic granulomatous disease

Answer 45

fatal disease causes by defective oxidative enzyme

Question 46

What are neutrophil extracellular traps (NETs)

Answer 46

Stimulated neutrophils release nuclear material and granular proteins extracellularly

Question 47

What are NETs neutrophils stimulated by

Answer 47

CXCL8 or LPS

Question 48

What nuclear material and granular proteins do NETs release extracellular

Answer 48

DNA, histones, granular proteins

Question 49

What does the extracellular degranulation in NETs creat

Answer 49

mesh that traps bacteria and the antimicrobial proteins kill the bacteria

Question 50

NET is NOT a result of neutrophil death but an active response to _____

Answer 50

inflammatory stimuli called as NETosis

Question 51

What is the fate of neutrophils after extended phagocytosis, killing, and digestion of baterial cells AND what does this form

Answer 51

die and lyse; forms pus

Question 52

What is the fate of macrophages

Answer 52

egest digested debris and allow insertion of microbial antigenic components into the plasma membrane for presentation to lymphocytes in the immunological response

Question 53

What are the major surface receptors of macrophages

Answer 53

1. complement receptors 2. antibody receptors

Question 54

How are macrophages innately activated

Answer 54

TLRs and related receptors

Question 55

What does IL-4, IL-13, and IL-10 do to macrophages

Answer 55

alternate activation- M2 cells (tissue repair and less microbial killing)

Question 56

What does IFN-y do to macrohages

Answer 56

classical activation-M1 cells

Question 57

How does arginine cells activate macrophages

Answer 57

1. converted to ornithine, activates M2 cells 2. NOS2 activates M1 cells

Question 58

What is the role of macrophages in chronic infections

Answer 58

prolonged tissue irritation->M2 macrophages accumulate->IL-1, TGFB, fibroblast GF, angiogenic factors->fibrosis->granuloma formation

Question 59

how do macophages remove dying neutrophils

Answer 59

when CD31 fails to reply, neutrophil is phagocytosed

Question 60

What cells begin the healing process in damaged tissues?

Answer 60

macrophages