killing pathogens

Question 1

What cytokine does the effector T cell Th1 produce and its role

Answer 1

Produces IFN-y(gamma) and v good at activating macrophages to improve phagocytosis

Question 2

What cytokines does the effector T cell Th2 produce and their roles

Answer 2

IL-4
IL-5
IL-13
Can activate eosinophils and mast cell activation

Question 3

What cytokines does the effector T cell Th17 produce and its role

Answer 3

IL-17
IL-22
Activate and recruit neutrophils

Question 4

What does signal 3 direct

Answer 4

Directs T cell effector function

Question 5

How is signal 3 induced

Answer 5

Signal 3 given by cytokines and tells T cell the infection type (bacteria, virus, parasite) so which subset it can differentiate to

Question 6

What happens after a T cell has differentiated

Answer 6

Th1/2/17 cells migrate to infection site to aid innate immune response

Question 7

What are the different classes of B cells

Answer 7

IgM
IgA
IgG
IgE

Question 8

What are characteristics of igM

Answer 8

Good complement fixer
Good opsonizer
First antibody made

Question 9

What are characteristics of IgA

Answer 9

Resistant to stomach acid
Protects mucosal surfaces
Secreted in milk

Question 10

What are characteristics of IgG

Answer 10

Ok complement fixer
Good opsonizer
Helps NK cell kill
Can cross placenta

Question 11

What are characteristics of IgE

Answer 11

Defends against parasites
Causes anaphylactic shock
Causes allergies

Question 12

How does the classical pathway function

Answer 12

Uses Ab (IgM/IgG) to identify pathogen
Ab has high affinity for its Ag increasing specificity and efficiency of complement activation

Question 13

What are the three main effector functions of complement

Answer 13

1)opsonisation to enhance phagocytosis
2)stimulating inflammation by recruiting and activating immune cells
3)lysing microbes and cells

Question 14

What are the by products of complement activation

Answer 14

C3a
C4a
C5a

Question 15

How do the byproducts of complement activation act

Answer 15

Act locally - recruit cells to infection site and activate cells

Question 16

What is the respiratory burst in phagosome killing

Answer 16

The enzyme phagocyte oxidase + cofactor NADPH oxidase initiate respiratory burst coverting O2 into reaction oxygen species e.g hydrogen peroxide

Question 17

What can neutrophils produce that degrades bacteria

Answer 17

Elastase

Question 18

How does a neutrophil die

Answer 18

Process called NETosis

Question 19

How does NETosis work

Answer 19

Nucleus swells and burst extruding DNA which has anti-microbial molecules attached => can trap and kill bactreia, fungi and viruses

Question 20

Which T helper cells enhance immunity to helminths

Answer 20

T helper 2 cells (Th2)

Question 21

How does Th2 cells enhance immunity to helminths

Answer 21

IL-4 and IL-13 enhance muscle contractions and IL-4 promotes mast cell degranulation

Question 22

How do memory T and B cells estalist effector functions

Answer 22

T cells committed to correct phenotype - Th1/T2/Th17
B cells committed to correct isotype/class - IgM, IgG, IgA, IgE

Question 23

Why are immune cells targets for infection

Answer 23

Evading the killing mechanism makes infection easier (macrophage)
Immune cells migrate around the host - good transporters
Immune evasion makes it easier to manipulate immune pathways

Question 24

What are characteristics of listeria monocytogenes

Answer 24

Can break out of phagosome and then lives ＋replicates in the cytosol
Uses host actin to move within and between cells

Question 25

How are macrophages fully activated

Answer 25

Via the cytokine IFN-y(gamma).

Question 26

What is mycobacterium tuberculosis good at

Answer 26

Evading phagocytosis

Question 27

What does mycobacterium tuberculosis result in

Answer 27

Chronic infections w continual production of IFN-y(gamma) and macrophage activation

Question 28

What do viral infections stimulate the production of

Answer 28

Type 1 interferons

Question 29

What are the types of interferons

Answer 29

IFN-a(alpha) IFN-B(beta)

Question 30

What do type 1 IFNs induce

Answer 30

Anti-viral state in cells that protects them from being infected

Question 31

What are the functions of type 1 IFNs

Answer 31

Inhibition of viral gene expression Induces apoptosis Promote T cell and NK cell activation

Question 32

How does the Type 1 IFN function by inhibiting viral gene expression

Answer 32

Block viral transcription and translation Viral RNA degradation Autophagy (cells eat own organelles)

Question 33

How does the Type 1 IFN function by inducing apoptosis

Answer 33

Misfolded viral proteins triggers unfolded protein response causing apoptosis

Question 34

How does the Type 1 IFN function by promoting T cell and NK cell activation

Answer 34

Sequester lymphocytes in LN Increases cytotoxicity of CTL and NK cells Promote Th1 differentiation

Question 35

What do NK (natural killer) cells target

Answer 35

Target cels infected with bacteria, virus and protozoa

Question 36

How are perforin and granzyme used as killing mechanisms

Answer 36

Perforin creates a pore in the infected cells membrane Granzyme enters via pore and induces apoptosis

Question 37

How do Fas and Fas ligand mediated cell killing work

Answer 37

Target cells express Fas ligand CTL (cytotoxic T lymphocyte)/NK express FAS ligand (FasL) activating fas Fas activation signals apoptosis