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VMPM (Immunology) > Lecture 3 > Flashcards

Lecture 3 Flashcards

1
Q
A
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2
Q

Identify the following cell types.

A
  1. Eosinophil.
  2. Neutrophil.
  3. Basophil.
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3
Q

Define “acute inflammation.”

A

Accumulation of neutrophils in the tissues.

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4
Q

What is pus composed of?

A

Dead and dying neutrophils.

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5
Q

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

A

FALSE

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

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6
Q

What might you find in a neutrophil’s vesicles?

A

Proteolytic enzymes

Bacteriocides

Glycogen

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7
Q

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

A

1-2 days.

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8
Q

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

A

8-10 hours.

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9
Q

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

A

FALSE

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

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10
Q

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

A

Anaerobic respiration.

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

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11
Q

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

A

Phagocytosis.

Motility.

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12
Q

Name the four major receptor types on the neutrophil surface.

A

Cell adhesion molecules.

Antibody receptor (FcR).

Complement receptors.

Cytokine (inflammatory mediator) receptors.

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13
Q

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

A

Margination.

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14
Q

Where does neutrophil margination occur?

A

Post-capillary venules.

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15
Q

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

A

Stress leukogram.

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16
Q

How do anti-inflammatories affect neutrophils?

A

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

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17
Q

Which endothelial molecules are responsible for neutrophil rolling?

A

Selectins.

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18
Q

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

A

Integrins.

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19
Q

Define diapedesis.

A

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.

20
Q

Define chemotaxis.

A

The movement of a cell in response to chemical stimuli.

Neutrophils rely on chemotaxis to locate bacteria in the tissues.

21
Q

Define opsonization.

A

When a pathogen is marked and prepared for phagocytosis.

Opsonin molecules may include:

Antibody

Complement molecules

Some acute phase proteins

22
Q

What is the name of the pictured process?

A

Diapedesis.

This is a neutrophil squeezing in between endothelial cells.

23
Q

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

A

TRUE

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

24
Q

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

A

Phagosome.

25
Q

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

A

Phagolysosome.

26
Q

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

A

If the microbe’s membrane is more hydrophobic than the neutrophil’s, the neutrophil can bind.

Otherwise, the microbe must be opsonized.

27
Q

How does a bacterial capsule protect a bacterium from neutrophils?

A

The hydrophilic capsule prevents phagocytosis.

28
Q

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

A

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

29
Q

Name the three killing methods used by a neutrophil.

A
  1. Enzymes from granules.
  2. Oxidative metabolism (respiratory burst).
  3. Defensins.
30
Q

True or False: Defensins are effective against bacterial capsules.

A

FALSE

Defensins must make contact with the bacterial membrane in order to be effective.

31
Q

How do defensins work?

A

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

32
Q

Why is lactoferrin effective against bacteria?

A

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

33
Q

Describe the pH changes within the phagosome.

A
  1. Killing phase - pH is basic, allowing defensins to function.
  2. Digestion phase - pH is acidic, allowing hydrolases to function.
34
Q

What is the most potent killing mechanism of a neutrophil?

A

Respiratory burst.

35
Q

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

A

FALSE

Oxygen is required to create reactive oxygen intermediates.

36
Q

What factors can upregulate neutrophil activity?

A

Innate defense cytokines

T helper cytokines

37
Q

What is a NET?

A

Neutrophil Extracellular Trap

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

38
Q

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

A

Upregulate integrins to facilitate neutrophil movement to the target tissues.

39
Q

What is the primary function of eosinophils?

A

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

40
Q

What color do an eosinophil’s granules stain?

A

Pink

41
Q

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

A

FALSE

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

42
Q

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

A

TRUE

43
Q

What factors can increase eosinophil activity?

A

Cytokines from T cells and macrophages.

44
Q

What factors can decrease eosinophil activity?

A

Stress and glucocorticoids

45
Q

What factors can decrease neutrophil activity?

A

Stress, glucocorticoids

Some viral infections

Bacterial virulence factors

Prepartrurient period

Neonate (less efficient neutrophil function. Improves over first week of life).

VMPM (Immunology) (15 decks)

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