Opsonization and phagocytosis

Question 1

___ is the process of attaching opsonins, such as IgG or complement fragments, to microbial ___ to target the microbes for ___.

Answer 1

Opsonization; surfaces; phagocytosis

Question 2

what cells have receptors that can recognize macromolecules attached to the surface of a microbe?

Answer 2

neutrophils and macrophages

Question 3

What are the two primary opsonins?

Answer 3

IgG and complement factor C3

Question 4

T/F. Most microorganisms will be phagocytosed without opsonins.

Answer 4

False, most microorganisms will NOT be phagocytosed without opsonins.

Question 5

___ extend to cover particle (but only the part that is opsonized).

Answer 5

Pseudopods

Question 6

Changes the organism’s surface from ___ (relative to the PMN) to more ___ increases ingestion.

Answer 6

hydrophilic; hydrophobic

Question 7

IgG antibodies bind to microbes and are then recognized by ___ receptors on phagocytes.

Answer 7

Fc

Question 8

___ receptor signals activate phagocyte and leads to engulfment of the particles. The particles are internalized into vesicles known as ___, which fuse with ___, and the phagocytosed particles are destroyed in these phagolysosomes.

Answer 8

Fc; phagosomes; lysosomes

Question 9

T/F. IgG, not complement fragments, mediate opsonization.

Answer 9

False. IgG and complement fragments mediate opsonization.

Question 10

Binding of ___ to microbe by recognition of the ___ receptor causes ___ of the microbe.

Answer 10

C3b; C3b; phagocytosis

Question 11

Cell bound ___ is an opsonin that promotes phagocytosis.

Answer 11

C3b

Question 12

Complement activation leads to ___ activation and inflammation and tissue injury.

Answer 12

neutrophil

Question 13

What are the receptors for opsonins?

Answer 13

FCgamma on phagocytes

CR and leukocyte integrin Mac-1

Question 14

The Fc receptors are grouped based on what?

Answer 14

their affinity for heavy chains of different IgGs

Question 15

What are the two FcRs have a high affinity for immunoglobulin?

Answer 15

FCgammaRI and FCepisilonRI

Question 16

What region of the IgG receptor reacts with organism?

Answer 16

Fab-region

Question 17

What region of the IgG receptor is FcgammaR?

Answer 17

Fc domain on PMN

Question 18

T/F. The loss of CD16 “bright” peak is a signal for macrophages to phagocytose the neutrophils- they signal that they are apoptotic.

Answer 18

True

Question 19

What Fcgamma R subtype is the most important for phagocytosis of IgG coated particles and microorganisms?

Answer 19

RII

Question 20

Activation of ___ cascade causes proteolytic cleavage of complement factors creating potential ligands for complement receptors on neutrophil surfaces.

Answer 20

complement

Question 21

What type of complement related proteins are C3a and C5a?

Answer 21

chemotactic factors

Question 22

What type of complement related proteins are C3b and C3bi?

Answer 22

the main complement derived opsonins

Question 23

How many complement receptors are there?

Answer 23

4

Question 24

what is the major phagocytic cell in the innate immune response?

Answer 24

neutrophils

Question 25

What phagocytic cell is continually circulating, binding and releasing from the vascular endothelia and contains granules in the cytoplasm responsible for killing microbes?

Answer 25

neutrophils

Question 26

Matching: What does each neutrophil receptor recognize on bacteria?

1. LPS receptor
2. CR3,4
3. Scavenger receptor
4. Mannose receptor
5. Glycan receptor:

A. Complement (C’) receptors (C3b)
B. CD14
C. toll-like receptor-4
D. Polysaccharides
E. sialic acid-bearing protein
F. Binds mannose on bacteria, activates C’

Answer 26

1. B,C
2. A
3. E
4. F
5. D

Question 27

What cell that circulates in the blood and eventually move into the tissues to become macrophages functions to phagocytosize and produce cytokines?

Answer 27

monocytes

Question 28

Match:

1. Lung
2. Liver
3. Bone
4. Connective tissue
5. Kidney
6. Brain

A. Kupfer cells
B. Mesangial
C. Osteoclasts
D. Histocytes
E. Microglial cells
F. alveolar macrophages

Answer 28

1. F
2. A
3. C
4. D
5. B
6. E

Question 29

What receptors are found on macrophages?

Answer 29

LPS receptor-CD14
Toll-like receptors
Fc receptors
Mannose receptor
Complement receptors
IFNg receptor
Chemokine receptors

Question 30

T/F. Stress and injury are factors that increase PMNs but infection and increased cytokines decrease PMNs.

Answer 30

False. All (stress, injury, infection and increased cytokines) increase PMNs

Question 31

What are the two mechanisms for destruction and killing?

Answer 31

oxidative

non-oxidative (enzymes and cytoplasmic granules and pH changes)

Question 32

Once the microbes are inside a phagolysosome, how are they killed?

Answer 32

by ROS and NO

Question 33

What are the five phagocytic cells?

Answer 33

neutrophils (polymorphonuclear leukocytes - PMNs)
macrophages/monocytes
eosinophils
basophils
dendritic cells

Question 34

T/F. Macrophages ingest and degrade gram-negative bacteria and is activated by LPS to secrete cytokines.

Answer 34

True.

Question 35

What two cytokines cause local AND systemic effects?

Answer 35

IL-1, TNFalpha and IL-6

Question 36

What tactics are used by pathogens to avoid killing by phagocytes?

Answer 36

1. kill or be killed
2. inhibit opsonization or inactivate phagocytosis
3. survive intracellular killing