Acute inflammation cellular phase: neutrophil sequence and macrophage arrival

Question 1

What are the 7 events in the sequence of neutrophils in acute inflammation?

Answer 1

Margination, rolling, adhesion, transmigration and chemotaxis, phagocytosis, destruction of material, resolution

Question 2

How does vasodilation allow margination of neutrophils to occur in acute inflammation?

Answer 2

Blood flow slows so that neutrophils can marginate from centre of post-capillary venule to periphery

Question 3

What molecules are activated by cytokines for rolling of neutrophils in acute inflammation?

Answer 3

Selectins

Question 4

How do selectins cause neutrophils to roll along blood vessels in acute inflammation?

Answer 4

They are positioned as ‘speed bumps’ on endothelial cell surface of vessel wall, then they bind to sialyl Lewis-X on neutrophils, this causes rolling

Question 5

In neutrophil rolling in acute inflammation, what part of the neutrophil do selectins bind to?

Answer 5

Sialyl Lewis-X

Question 6

In adhesion of neutrophils in acute inflammation, what molecule is activated by chemokines and where is it located?

Answer 6

Integrins on neutrophil cell surface

Question 7

Why do activated integrins allow firm adhesion between neutrophils and endothelial cells of vessel walls in acute inflammation?

Answer 7

Activated integrins have higher affinity for adhesion molecules on endothelial cell surface

Question 8

What molecule mediates transmigration of neutrophils across spaces between endothelial cells in vessel walls in acute inflammation?

Answer 8

Platelet Endothelial Cell Adhesion Molecule-1

PECAM-1

Question 9

What structure in the neutrophil allow it to move towards pathogen by chemotaxis in acute inflammation?

Answer 9

Cytoskeleton

Question 10

How do chemoattractants activate the neutrophil for chemotaxis in acute inflammation?

Answer 10

Chemoattractant activates actin in cytoskeleton

Question 11

Give 4 examples of chemoattractants for neutrophil chemotaxis in acute inflammation?

Answer 11

Bacterial products

IL-8

C5a

LTB4 (leukotriene)

Question 12

How does the neutrophil recognise the target in phagocytosis of acute inflammation?

Answer 12

Opsonised target sends ‘eat-me’ signals

Question 13

What structure of the neutrophil changes shape to form a phagosome around the target in phagocytosis?

Answer 13

Pseudopods

Question 14

How is the phagolysosome formed in phagocytosis?

Answer 14

Phagosome is internalised and fuses with lysosome

Question 15

What 3 types of molecules destroy phagocytosed material inside the phagolysosome in oxygen-dependent killing?

Answer 15

Lysosomal enzymes

ROS

Reactive nitrogen species

Question 16

What enzyme assembles in the phagosome membrane in activated neutrophils to allow oxygen-dependent killing?

Answer 16

Phagocyte oxidase

Question 17

Which 2 molecules are converted from oxygen by phagocyte oxidase to allow oxygen-dependent killing?

Answer 17

Hydrogen peroxide

Superoxide

Question 18

What is myeloperoxidase?

Answer 18

Enzyme found in neutrophil granules that converts hydrogen peroxide into bleach/hypochlorite

Question 19

Is oxygen-dependent killing more or less effective than oxygen-independent killing?

Answer 19

More effective

Question 20

In oxygen-independent killing, what chemicals are used and where are they found?

Answer 20

Lysozymes in macrophages

Major basin protein in eosinophils

Generally chemicals are found in leucocyte cytoplasmic granules

Question 21

What occurs in resolution of acute inflammation?

Answer 21

After all pathogens die, neutrophils die by apoptosis within 24hrs of pathogen elimination, so that macrophage phase can start

Question 22

When does the macrophage phase start after acute inflammation?

Answer 22

2-3 days after start of acute inflammation

Question 23

What 3 events in the sequence of macrophages are different from how these events occur in the sequence of neutrophils in inflammation?

Answer 23

Phagocytosis, destruction of ingested material, resolution

Question 24

What method do macrophages use to destroy phagocytosed material in inflammation?

Answer 24

Oxygen-independent killing with lysozymes