2- Innate Immunity

Question 1

How does an exotoxin damage host tissues?

Answer 1

binds to a specific cell surface receptor

Question 2

How does an endotoxin damage host tissues?

Answer 2

It stimulates phagocytes to secrete cytokines and cause local or systemic symptoms

Question 3

What is the direct cytopathic effect?

Answer 3

Intracellular destrction by an an intracellular bacteria or virus.

Question 4

What is the complement system?

Answer 4

The first defense against pathogens using proteins that coat and kill the bacteria.

Question 5

What is the most important protein for the complement system?

Answer 5

C3

Question 6

How is the alternative pathway activated?

Answer 6

Triggered by microbial surface membranes or other innate immunity components.

Question 7

How is the lectin pathway activated?

Answer 7

Mannose-binding lectin binding to the pathogen surface.

Question 8

How is the innate classical pathway activated?

Answer 8

CRP

Question 9

How is the adaptive classical pathway activated?

Answer 9

By the binding of antibodies to the bacterial surfaces.

Question 10

Cleavage of C3 peptide yields what 2 important complement proteins?

Answer 10

C3a and C3b

Question 11

What is the function of C3a?

Answer 11

It’s an anaphylatoxin

Question 12

What is the function of C3b?

Answer 12

It’s an opsonin

Question 13

What is the function of C4b?

Answer 13

It’s an opsonin

Question 14

What is the function of C5a?

Answer 14

It’s both an anaphylatoxin and chemotractant

Question 15

What is the cause of hereditary angioedema?

Answer 15

A lack of C1 inhibitor. This allows the complement process to continuously run and causes edema in various organs and tissues.

Question 16

What is the end result of the complement system?

Answer 16

Membrane Attack Complex (MAC)

Question 17

What is the C# convertase of the alternative complement pathway?

Answer 17

C3bBb

Question 18

Why is C3bBb the amplification step of the alternative pathway?

Answer 18

Since it’s the C3 convertase and bound to the surface of the pathogen, lots of C3b is made and covers the pathogen for opsonization.

Question 19

What is the function of CR1?

Answer 19

Since it’s on the macrophage, it binds to C3b on the pathogen and eats it.

Question 20

What is the function of CR3 and CR4?

Answer 20

Same as CR1. On the macrophage, binds to C3b and allows the macrophage to feast.

Question 21

What proteins compose the MAC?

Answer 21

C5-9

Question 22

What infections might occur if there is a deficiency in any C5-9 proteins?

Answer 22

Neisseria infections

Question 23

What does the MAC do?

Answer 23

Make holes in the membranes of the bacteria.

Question 24

How do C3a and C5a act as anaphylatoxins?

Answer 24

They induce smooth muscle contraction and degrtanulation of basophils and mast cells.

Question 25

What is the general function of defensins?

Answer 25

They are + charged molecules that attract the - charged proteins of the pathogens, penetrate the membranes of the pathogens and destroy them.

Question 26

Where are α –defensins from?

Answer 26

Neutrophils and other cells of innate immunity like Paneth cells of the GI

Question 27

Where are β-defensins from?

Answer 27

Most epithelial surfaces- skin, respiratory, and urogenital tract.

Question 28

What is the process of macrophage activation and completion of phagocytosis?

Answer 28

Macrophage recognizes pathogen structures using various receptors --> M0 binds the pathogen --> internalize in a phagosome --> lysosome fuses with phagosome --> everything in the phagosome is destroyed

Question 29

What are toll-like receptors (TLR's)?

Answer 29

They are signalling receptors on cells that allows the body to detect pathogens based on pathogen structures. The "watchdogs" of the body.

Question 30

What are the function of IL-1β from macrophages?

Answer 30

They locally activate the lymphocytes and tissue destruction.

Question 31

What are the functions of TNF- α from macrophages?

Answer 31

Locally they increase vascular permability, systemically they induce fever.

Question 32

What are the functions of IL-6 from macrophages?

Answer 32

Induce fever systemically

Question 33

What is the function of CXCL8 (IL-8) from macrophages?

Answer 33

It's a local chemotactic factor for PMN's

Question 34

What are the functions of IL-12 from macrophages?

Answer 34

Locally they activate NK cells to secrete IFN-γ

Question 35

How does LSP activation of macrophages lead to septic shock?

Answer 35

LPS causes a widespread production of TNF- α, which dilates blood vessels and causes a massive leakage of fluids into tissues throughout the body.

Question 36

What are the 1st type of WBC to a site of infection?

Answer 36

Neutrophils

Question 37

How are neutrophils attracted to a site of infection?

Answer 37

CXCL8 from macrophages and C5a from the complement

Question 38

What are the 4 steps of extravasation of neutrophils into tissues

Answer 38

1. Rolling adhesion (selectins on neutrophil bind to vessel wall), 2. Tight binding (using integrin and CXCL8), 3. Diapedesis (sqeeze through the wall), 4. Migration (using CXCL8 gradient to infection)

Question 39

What is the cause of the respiratory burst?

Answer 39

Neutrophils, when they eat, increase O2 consumption, subsequently making superoxide radicals and H2O2

Question 40

What are the 3 proinflammatory cytokines?

Answer 40

IL-1, IL-6 and TNF-α

Question 41

What occurs during the acute phase response?

Answer 41

Acute phase proteins like mannose-binding lectin and CRP are made to enhance fixation of the complement on pathogens.

Question 42

What are the 2 functions of CRP?

Answer 42

Act as an opsonin and it triggers the classical complement pathway

Question 43

What are the 2 main functions of IFNα and IFNβ?

Answer 43

1. to interfere with viral replication and 2. activate NK cells to kill virus infected cells.

Question 44

What are the 2 main functions of NK cells?

Answer 44

1. to kill the infected cells using cytotoxic granules and 2. to release IFN-γ which recruits macrophages to the infection.

Question 45

What receptor on NK cells bind to the MIC-A and B of infected cells?

Answer 45

NKG2D