Lecture 3

Question 1

Identify the following cell types.

Answer 1

1. Eosinophil.
2. Neutrophil.
3. Basophil.

Question 2

Define “acute inflammation.”

Answer 2

Accumulation of neutrophils in the tissues.

Question 3

What is pus composed of?

Answer 3

Dead and dying neutrophils.

Question 4

True or False: Neutrophils have uncondensed chromatin, so they can readily regenerate.

Answer 4

FALSE

Neutrophils have condensed chromatin. They are short-lived, end-stage cells.

Question 5

What might you find in a neutrophil’s vesicles?

Answer 5

Proteolytic enzymes

Bacteriocides

Glycogen

Question 6

How long will a neutrophil live in normal (uninflamed) tissue?

Answer 6

1-2 days.

Question 7

How long does a neutrophil normally circulate in the blood stream?

Answer 7

8-10 hours.

Question 8

True or False: Neutrophils require specific antigens in order to attack pathogens.

Answer 8

FALSE

Neutrophils are part of the innate immune system and do not respond to specific antigens.

Question 9

Neutrophils store glycogen, which is unusual amongst leukocytes. What do they use it for?

Answer 9

Anaerobic respiration.

Useful for penetrating damaged tissue where the oxygen supply may be cut off.

Question 10

Neutrophils are not perfectly circular, but have a lot of extra membrane. Why is this?

Answer 10

Phagocytosis.

Motility.

Question 11

Name the four major receptor types on the neutrophil surface.

Answer 11

Cell adhesion molecules.

Antibody receptor (FcR).

Complement receptors.

Cytokine (inflammatory mediator) receptors.

Question 12

What is the term for a neutrophil slowly rolling along a blood vessel?

Answer 12

Margination.

Question 13

Where does neutrophil margination occur?

Answer 13

Post-capillary venules.

Question 14

What is the term for an acute neutrophilia in the blood induced by fear, epinephrine, or glucocoritcoids?

Answer 14

Stress leukogram.

Question 15

How do anti-inflammatories affect neutrophils?

Answer 15

They disrupt margination, preventing neutrophils from migrating to target tissues.

Question 16

Which endothelial molecules are responsible for neutrophil rolling?

Answer 16

Selectins.

Question 17

Which endothelial molecules are responsible for neutrophil sticking (i.e. cause the neutrophil to stop rolling)?

Answer 17

Integrins.

Question 18

Define diapedesis.

Answer 18

The passage of a cell through the intact endothelial layer to reach a target tissue.

In neutrophils, diapedesis occurs after the neutrophil has encountered integrin molecules.

Question 19

Define chemotaxis.

Answer 19

The movement of a cell in response to chemical stimuli.

Neutrophils rely on chemotaxis to locate bacteria in the tissues.

Question 20

Define opsonization.

Answer 20

When a pathogen is marked and prepared for phagocytosis.

Opsonin molecules may include:

Antibody

Complement molecules

Some acute phase proteins

Question 21

What is the name of the pictured process?

Answer 21

Diapedesis.

This is a neutrophil squeezing in between endothelial cells.

Question 22

True or False: A neutrophil will not bind to anything more hydrophilic than itself.

Answer 22

TRUE

Neutrophils can bind to objects that are more hydrophobic than themselves.

Question 23

What is the term for an engulfed membrane-bound vesicle containing a microbe?

Answer 23

Phagosome.

Question 24

What is the term for a phagosome that has fused with a lysosome?

Answer 24

Phagolysosome.

Question 25

What is required for a neutrophil to bind to a microbe?

Answer 25

If the microbe's membrane is more hydrophobic than the neutrophil's, the neutrophil can bind. Otherwise, the microbe must be opsonized.

Question 26

How does a bacterial capsule protect a bacterium from neutrophils?

Answer 26

The hydrophilic capsule prevents phagocytosis.

Question 27

Mycobacteria are effective intracellular pathogens. How do they enter the cell? How do they survive once inside?

Answer 27

Mycobacteria have hydrophobic capsules, facilitating their uptake by neutrophils. Once inside, they resist being killed in the phagosome.

Question 28

Name the three killing methods used by a neutrophil.

Answer 28

1. Enzymes from granules. 2. Oxidative metabolism (respiratory burst). 3. Defensins.

Question 29

True or False: Defensins are effective against bacterial capsules.

Answer 29

FALSE Defensins are only effective against membranes.

Question 30

How do defensins work?

Answer 30

Have hyrophobic and hydrophilic ends. The hydrophobic ends insert into the membrane. Multiple molecules form a pore in the membrane, causing cellular lysis.

Question 31

Why is lactoferrin effective against bacteria?

Answer 31

Bacteria require iron for growth. Lactoferrin sequesters iron through chelation, preventing bacterial growth.

Question 32

Describe the pH changes within the phagosome.

Answer 32

1. Killing phase - pH is basic, allowing defensins to function. 2. Digestion phase - pH is acidic, allowing hydrolases to function.

Question 33

What is the most potent killing mechanism of a neutrophil?

Answer 33

Respiratory burst.

Question 34

True or False: Neutrophils can perform respiratory burst under anaerobic conditions.

Answer 34

FALSE Oxygen is required to create reactive oxygen intermediates.

Question 35

What factors can upregulate neutrophil activity?

Answer 35

Innate defense cytokines T helper cytokines

Question 36

What is a NET?

Answer 36

Neutrophil Extracellular Trap If a neutrophil cannot phagocytose a pathogen, it undergoes netosis, whereby it explodes and casts a net of DNA and histones.

Question 37

How will endothelial cells respond to "danger signals" from the tissues (i.e. PAMPs and DAMPs)?

Answer 37

Upregulate integrins to facilitate neutrophil movement to the target tissues.

Question 38

What is the primary function of eosinophils?

Answer 38

Defense against multicellular parasitic invasion (e.g. helminths).

Question 39

What color do an eosinophil's granules stain?

Answer 39

Pink

Question 40

True or False: Eosinophils rely on phagocytosis to kill pathogens.

Answer 40

FALSE An eosinophil's targets are too large to be phagocytosed. Damaging products are released extracellularly.

Question 41

True or False: An eosinophil can perform diapedesis and chemotaxis much like a neutrophil.

Answer 41

TRUE

Question 42

What factors can increase eosinophil activity?

Answer 42

Cytokines from T cells and macrophages.

Question 43

What factors can decrease eosinophil activity?

Answer 43

Stress and glucocorticoids

Question 44

What factors can decrease neutrophil activity?

Answer 44

Stress, glucocorticoids Some viral infections Bacterial virulence factors Prepartrurient period Neonate (less efficient neutrophil function. Improves over first week of life).