5 explo Neutrophils at the crossroads of innate and adaptive immunity

Question 1

most abundant leukocytes in blood

Answer 1

neutrophils

Question 2

the first type of leukocytes to arrive at affected tissues and display potent micro-
bicidal functions

Answer 2

neutrophils

Question 3

they have been classically viewed as the first line of defense.

Answer 3

neutrophils

Question 4

are polymorphonuclear and granular leukocytes
that function as an essential part of the innate immune system. in humans, it contain 50-70% of all circulating leukocytes.

Answer 4

neutrophils

Question 5

average size of mature neutrophils

Answer 5

7-10 micrometer (um)

Question 6

Neutrophils can rapidly move from the blood into sites of infection or inflammation through a process known as the

Answer 6

leukocyte adhesion cascade.

Question 7

neutrophils die by _______ and are eliminated by macrophages.

Answer 7

apoptosis

Question 8

first line of defense

Answer 8

neutrophils

Question 9

are produced from committed hematopoietic progenitor cells in the hematopoietic cords located at venous sinuses in the bone marrow.

Answer 9

neutrophils

Question 10

The CMP cells, in turn, transform into ____________________ which mature into neutrophils

Answer 10

granulocyte–monocyte progenitors

Question 11

The master regulator of both granulopoiesis and neutrophil release
from the bone marrow is ____ which regulates granulopoiesis
by inducing proliferation of granulocytic precursors in the bone
marrow,28 and regulates mature neutrophil release from the bone
marrow by interfering with the CXCR4-CXCL12 axis.26

Answer 11

G-CSF

Question 12

The chemokine _____ (stromal-derived factor-1/SDF-1) is produced by bone mar-
row stromal cells, whereas bone marrow neutrophils express the ______

Answer 12

CXCL 12 , CXCR4

Question 13

Lack of the ______receptor results in severe neutropenia both in mice30

Answer 13

G-CSF

Question 14

what is G-CSF

Answer 14

Granulocyte colony stimulating factor (G-CSF) is a type of growth factor that increases the number of white blood cells in the blood.

Question 15

Production of G-CSF is regulated by _______ which produce ______

Answer 15

γδ T lymphocytes , IL-17

Question 16

The production of IL-17 is in turn regulated by ____ and ____ producing IL-23.

Answer 16

tissue-resident macrophages , dendritic cells (DCs)

Question 17

during altered conditions, such as bleeding or infections, when extra cells are required the hematopoietic system is capable of rapidly increasing its cellular output. This stress-induced response has been called

Answer 17

emergency hematopoiesis.

Question 18

_____ are considered short-lived cells. Once in the blood, neutrophils present a short circulating half-life of ______ hours in humans

Answer 18

neutrophils , 6-8

Question 19

Mature neutrophils can divide in response to serum amyloid A, and in the spleen a group of neutrophils proliferates and is mobilized to fight a ________________ infection

Answer 19

Streptococcus pneumoniae

Question 20

Migration of neutrophils into the affected site proceeds through a systematically
controlled process known as

Answer 20

leukocyte adhesion cascade

Question 21

Neutrophil transmigration through the endothelium can take place via

Answer 21

paracellular or a transcellular route.

Question 22

In the _________ route neutrophils move through endothelial cell junctions whereas in the _______ route neutrophils pass directly through the endothelial cell body.

Answer 22

paracellular , transcellular

Question 23

____ are contractile cells located at the abluminal site of small blood vessels and are responsible for controlling capillary permeability.

Answer 23

pericytes

Question 24

Elongation and passage of the uropod between pericytes is regulated mainly by _____

Answer 24

β2 integrins

Question 25

Once neutrophils move into tissues, they follow __________ to reach infection or inflammation sites. Some chemoattractans for neutrophils are chemokines, __ __ __

Answer 25

chemoattractant gradients, CXCL8 and CXCL2

Question 26

Once neutrophils have completed their antimicrobial functions, they undergo _____.

Answer 26

apoptosis

Question 27

Failure to clear these apoptotic cells, results in __________ and release of products that generate proinflammatory signals.

Answer 27

secondary necrosis

Question 28

T/F: Dying neutrophils are believed to be cleared by macrophages in the bone marrow, liver, and spleen

Answer 28

TRUE

Question 29

In the liver, resident macrophages (Kupffer cells) are thought to eliminate neutrophils that die in the ____.

Answer 29

vasculature

Question 30

Neutrophils form ____ while fighting certain infections, and this product can leave the body through the skin.80

Answer 30

pus

Question 31

in urinary tract, infections neutrophils can be eliminated in the _____

Answer 31

bladder

Question 32

neutrophils are required to protect tissues constantly exposed to the environment such as the ______ and the _______.

Answer 32

eye , oral mucosa

Question 33

T/F: Neutrophils migrate to the surface of the eye for cleaning it during the night, and afterward they die in this site

Answer 33

TRUE

Question 34

there is a constant migration of neu trophils into the mouth for protection against the ______

Answer 34

oral microbiota

Question 35

It was calculated that around _____ neutrophils migrate into the oral cavity every minute under basal conditions.

Answer 35

30 000

Question 36

It was calculated that around _____ neutrophils migrate into the oral cavity every minute under basal conditions.

Answer 36

30 000

Question 37

a sterile tissue injury caused a strong inflammation response with neutrophils transmigrating out of the vasculature to the site of injury. Then, many neutrophils were observed to leave the tissue and reenter the vasculature. This process is known as??

Answer 37

reverse transmigration

Question 38

ANTIMICROBIAL MECHANISMS OF NEUTROPHILS

Answer 38

degranulation, production of ROS, phagocytosis, and formation of NET

Question 39

four types of granules in neutrophils.

Answer 39

Primary or azurophil granules containing MPO, NE, azuracidin, defensins.

Question 40

______ granules are the first to be produced during the development of the neutrophil

Answer 40

Azurophil

Question 41

Secondary or specific granules contain ______, which sequesters iron important for microbial growth.

Answer 41

lactofferin

Question 42

Secondary granules also contain __________ and _________. Tertiary or gelatinase granules contain gelatinase proteins such as matrix metalloproteinase-9 (MMP-9), which is important for degradation of ECM proteins.

Answer 42

cathelicidin and metalloproteinases

Question 43

The order of degranulation is as follows:

Answer 43

secretory vesicles and tertiary granules > secondary granules > primary granules.

Question 44

Primed neutrophils typically present enhanced generation of ROS by the NADPH oxidase, and it seems that NADPH oxidase-derived ROS are necessary for preventing excessive degranulation of tertiary granules.

Answer 44

o

Question 45

Neutrophils activate the ______ to generate large amounts of superoxide, which is as a precursor of H2O2 and other forms of ROS with potent antimicrobial activity.103

Answer 45

NADPH oxidase

Question 46

The critical role of NADPH oxidase in controlling microbial infections became evident in individuals with _______________

Answer 46

chronic granulomatous disease

Question 47

Patients with chronic granulomatous disease have poor ____ oxidase enzymatic activity, resulting in life-threatening bacterial and fungal infections.

Answer 47

NADPH

Question 48

The activity of the NADPH oxidase can also be regulated by _______ fluxes and by voltage gated proton channels, and chloride channels.

Answer 48

calcium

Question 49

large amounts of ____ are produced during neutrophil phagocytosis,

Answer 49

superoxide

Question 50

Phagocytosis is a receptor-mediated process during which a particle larger than 0.5 μm is internalized by the cell into a vacuole called the____

Answer 50

phagosome

Question 51

Neutrophils recognize pathogens through PAMPs or through

Answer 51

opsonins

Question 52

NETosis is a dynamic cell death program for neutrophils that is responsible for

Answer 52

NET formation

Question 53

T/F: NET are considered a beneficial neutrophil response with the main function of controlling the dissemination of infectious microorganisms.

Answer 53

true

Question 54

Neutrophils migrate into lymph nodes close to inflamed tissues via ___ lymphatics.

Answer 54

afferent

Question 55

it was found that neutrophils can enter lymph nodes not only via lymphatic vessels but also from ___, across high endothelial venules (HEVs) during infection,159

Answer 55

blood

Question 56

Neutrophils can regulate the adaptive immune response by activating or by inhibiting _____ responses.

Answer 56

T lymphocyte

Question 57

Neutrophils can also directly modulate _________ activation survival and differentiation by means of secretion of cytokines such as BAFF

Answer 57

B lymphocyte

Question 58

Neutrophils produce ______(Arg-1) and store it in azurophilic granules. Release of (Arg-1) in close proximity of lymphocytes inhibits ________ functions.

Answer 58

arginase 1, T lymphocyte

Question 59

neutrophils show circadian phenotype changes, in a process known as ___

Answer 59

aging