4: Innate Immunity

Question 1

Four intracellular pathogens + four extracellular pathogens

Answer 1

Intracellular: bacteria, Protozoa, viruses, mycobacterium

Extracellular: bacteria, Protozoa, parasites, fungi

Question 2

Four major players in intracellular infections

Answer 2

CTLs, NK cells, T cells, macrophages

Question 3

Three major players in extracellular infections

Answer 3

Neutrophils, Abs, complement

Question 4

What is an important bridge between innate and adaptive immunity?

Answer 4

PRRs

Question 5

What can PRRs do?

Answer 5

Cause activation/maturation of APCs

Question 6

What cytokines direct development of Th1 and Th2?

Answer 6

Th1: IL-12
Th2: IL-4

Question 7

Th1 vs Th2: intracellular vs extracellular pathogens?

Answer 7

Th1: intracellular
Th2: extracellular

Question 8

Major cytokine that mediates innate immunity

Answer 8

IFN type 1

Question 9

What cytokine is released by virally infected cells?

Answer 9

IFN type I (a/B)

Question 10

What do viruses release from host cells to activate macrophages and DCs?

Answer 10

PAMPs and DAMPs

Question 11

Where do virally infected cells present their viral peptides?

Answer 11

MHC Class I

Question 12

Five cytokines from macrophages and their functions

Answer 12

IL-8: recruit neutrophils
MCP-1: recruit monocytes
IL-1, TNF-a, IL-6: acute phase response

Question 13

What is the acute phase response? (Three cytokines, three effects)

Answer 13

Formed by IL-1, TNF-a, and IL-6 -> causes fever, APP induction, and arthralgia/myalgia

Question 14

Potency of cytokines causing fever

Answer 14

1. IL-1
2. TNF-a
3. IL-6

Question 15

Potency of cytokines causing APP induction

Answer 15

1. IL-6
2. IL-1
3. TNF-a

Question 16

What one cytokine causes arthralgia/myalgia?

Answer 16

TNF-a

Question 17

How do DCs bias CD4 differentiation

Answer 17

Based on whether DC has a viral or bacterial Ag

Question 18

Two cytokines by Th1 cells and their functions

Answer 18

IL-1: in LN, proliferation of CTLs

IFN-y: stimulate macrophages

Question 19

Which two cell types must work with macrophages bc they dont kill viral particles, just kill host cells

Answer 19

NK cells, CTLs

Question 20

What two cytokines increase CTL resistance to apoptosis?

Answer 20

IFN-y, IL-2

Question 21

First Ig produced by B cells + its affinity and avidity

Answer 21

IgM - low affinity, high avidity

Question 22

Why is IgM high avidity?

Answer 22

10 binding sites

Question 23

How do B cells learn how to isotype switch to IgG and IgA?

Answer 23

By interaction with Th2 cells

Question 24

When Abs act as opsonin, what two things do they attach to?

Answer 24

1. Epitope on Ag

2. Fc portion binds phagocyte receptor

Question 25

What two stress-associated molecules are presented on infected cells acting as killing signals for NK cells?

Answer 25

MICA, MICB

Question 26

Two receptor types on NK cells and what they recognize on infected cells

Answer 26

1. KARS: recognize MICA, MICB | 2. KIRS: recognize class I MHC

Question 27

KAR vs KIR activation in NK cells

Answer 27

KAR activation -> activation of protein tyrosine kinases in NK cell KIR activation -> activation of protein tyrosine phosphatases in NK cell

Question 28

How are NK cells activated by microbes?

Answer 28

They are not

Question 29

Three steps in NK cell killing

Answer 29

1. Perforins -> make a hole 2. Granzymes -> enter hole and digest enzymes 3. Enemy cell undergoes apoptosis

Question 30

Macrophage/NK amplification loop

Answer 30

1. Macrophages make IL-12 -> stimulate NK cells to produce IFN-y 2. IFN-y activates macrophages to phagocytose

Question 31

What type of activation occurs when macrophages are activated with IFN-y

Answer 31

Classical M activation

Question 32

Two principle pathogenic mechanisms of bacteria

Answer 32

1. Inflammation/tissue destruction | 2. Bacterial toxin

Question 33

Bacterial endotoxins vs exotoxins

Answer 33

Endotoxins: in bacterial cell walls, not released by living bacteria Exotoxins: constantly secreted by bacteria

Question 34

Example of an endotoxin

Answer 34

LP: in gram negative bacteria

Question 35

Three examples of bacterial exotoxins

Answer 35

Diphtheria toxin, cholera toxin, tetanus toxin

Question 36

What complement pathway can CRP activate?

Answer 36

Classical pathway

Question 37

Major job of C3b

Answer 37

Opsonize bacteria -> bind CR1 on macrophage/neutrophil surface to recruit phagocytes to engulf bacteria

Question 38

How does opsonization bring bacteria and phagocyte together?

Answer 38

It allows two negatively charged cell walls to come together

Question 39

Name for C3a and C5a

Answer 39

Anaphylatoxins

Question 40

Three functions of anaphylatoxins

Answer 40

1. Activate mast cells 2. Mediate leukocyte chemotaxis 3. Attract neutrophils to infection

Question 41

What do mast cells release and what does this do?

Answer 41

Histamine and proteases -> enhanced blood flow -> edema, itchiness, irritation

Question 42

Macrophage function on endothelial cells

Answer 42

Increases CAMs, especially P/E selectins

Question 43

What TLRs recognize gram positive vs gram negative bacteria

Answer 43

Gram positive: TLR2, TLR6 | Gram negative: TLR4

Question 44

What does local inflammation around an LN cause

Answer 44

Upregulation of CAMs on HEVs -> T and B cells enter en masse

Question 45

Four major players in helminths infections

Answer 45

1. Eosinophils 2. Basophils 3. Mast cells 4. IgE

Question 46

Which Th cell is important in fungal infections, and which facilitates the fungus?

Answer 46

Th1 fights fungus, Th2 helps fungus