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Sp 15-Micro Final > Opsonization and Phagocytosis > Flashcards

Opsonization and Phagocytosis Flashcards

1
Q

What is opsonization?

A

the process of attaching opsonins, such as IgG or complement fragments, to microbial surfaces to target the microbes for phagocytosis

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2
Q

What are opsonins?

A

Macromolecules attached to the surface of a microbe that can be recognized by receptors on neutrophils and macrophages

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3
Q

What are the primary opsonins?

A

IgG

Complement factor C3

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4
Q

True or False: Most microorganisms do not need opsonins in order to be phagocytosed.

A

False, Most microorganisms will NOT be phagocytosed without opsonins present.

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5
Q

Opsonins change the organism’s surface from _________ (relative to the PMN) to more _______.

A

Hydrophilic –> Hydrophobic

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6
Q

____ receptors on a phagocyte will bind to IgG during opsonization of a microbe.

A

Fc

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7
Q

How does IgG work to mediate phagocytosis of a microbe?

A
  • IgG attaches to Microbe
  • Fc on a phagocytic cell binds to IgG-tagged microbe
  • Fc receptor signal activates phagocyte
  • Phagocytosis of microbe
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8
Q

How do complement fragments mediate phagocytosis of a microbe?

A
  • C3b (or C4b) bind to the microbe
  • Phagocyte C3b-Receptor recognizes bound C3b
  • Phagocytosis of microbe
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9
Q

What are the complement by products of neutrophil activation (inflammation/tissue injury)?

A

C5a and C3a

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10
Q

What are the three common receptors for opsonins?

A 
Fc Lambda (on phagocytes)
CR
leukocyte integrin Mac-1
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11
Q

When talking about IgG receptors, what are the three classes of the Fc domain on neutrophils (Fc lambda-R)?

A

Fc lambda-R I (CD64)
Fc lambda-R II (CD32)
Fc lambda-R III (CD16)

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12
Q

What does it mean for a neutrophils to “display death sign”?

A

The loss of CD16 (Fc lambda-RIII) creates a signal for macrophages to phagocytose the neutrophils.

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13
Q

Which Fc-lambda R is most important for phagocytosis of IgG coated particles and microorganisms?

A

RII (CD32)

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14
Q

Activation of complement cascade causes _______cleavage of complement factors, creating potential ligands for complement receptors on neutrophil surfaces.

A

Proteolytic

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15
Q

____ and ____ are chemotactic factors within the complement system.

A

C3a and C5a

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16
Q

____ and ____ are the main complement derived opsonins.

A

C3b and C3bi

17
Q

Name the receptors for fragments of C3.

A

Type 1: CR1 –phagocytosis, clears immune complexes
Type 2: CR2 – coreceptor for B cell activation
Type 3: CR3 – phagocytosis, leukocyte adhesion
Type 4: CR4 – phagocytosis

18
Q

What is the major phagocytic cell in the innate immune response that is continually circulating?

A

Neutrophils

19
Q

What part of the neutrophil is responsible for killing microbes?

A

Primary Granules

Secondary Granules

20
Q

The neutrophil expresses receptors for many bacterial constituents. What are the seven receptors mentioned?

A 
LPS Receptor
CR4
Glycan Receptor
Mannose Receptor
CR3
Scavenger Receptor
TLRs
21
Q

What is the function of macrophages?

A

Phagocytosis and cytokine production

22
Q

What is the differences between monocytes and macrophages?

A
  • Monocytes CIRCULATE in the blood

- monocytes differentiate into Macrophages once they enter tissues

23
Q

What are the common receptors for macrophages?

A 
LPS receptor-CD14
TLR
Fc receptors
mannose receptors
Chemokine receptors
IFN
24
Q

What factors will increase the number of PMNs?

A

Stress
Injury
Infection
increased cytokines

25
Q

What are the two primary mechanisms of destruction and killing?

A
  1. Oxidative Mechanisms (Reactive Oxygen Species)

2. Non-Oxidative Mechanisms

26
Q

How would PMN utilize non-oxidative mechanisms for killing and destruction?

A

Enzymes
Cytoplasmic Granules
pH changes

27
Q

What are the 5 kinds of phagocytic cells?

A
  1. Neutrophils (PMNs)
  2. Macrophage/monocytes
  3. Eosinophils
  4. Basophils
  5. Dendritic Cells
28
Q

What are the three mentioned tactics used by pathogens to avoid killing by phagocytes?

A
  1. Cytotoxicity (kill or be killed)
  2. Inhibit opsonization or inactivate phagocytosis
  3. Survive intracellular killing

Sp 15-Micro Final (12 decks)

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