Immunology 2

Question 1

What are defensins

Answer 1

V.small anti microbial peptides produced by leukcytes and epithelial cells that can insert themselves into membranes of microbes and disrupt their membrane

Question 2

What secreted Ig activates complement by binding c1q?

Answer 2

IgM and IgG

Question 3

What if tigger phagocyte binding?

Answer 3

IgG and IgA ( via FcgammaR and FcalphaR)

Question 4

What Ig binds to mast cells?

Answer 4

IgE via FcelipsumR

Question 5

What Ig bind NK cells

Answer 5

IgG

Question 6

Describe neutralisation by antibodies

Answer 6

By binding to microbes or toxins secreted by microbes their activity can be blocked.

Question 7

What is complement?

Answer 7

A collection of proteins found in circulation and tissue fluid

Question 8

Can complement proteins act as activation enzymes?

Answer 8

Yes

Question 9

What is the main event of complement activation?

Answer 9

The conversion of C3 to C3a and C3b

Question 10

How is the classical pathway activated?

Answer 10

Antigen binds to IgM or IgG that then binds complement proteins c1q ( looks like bunch of tulips)

Question 11

How many Ig must c1q bind to be activated?

Answer 11

2 or more IgG or one IgM

Question 12

What proteins are associated with c1q?

Answer 12

C1r and c1s

Question 13

How is c3 convert as formed in the classical pathway?

Answer 13

C1 r and c1s activate c4 and c2 and splits them into fragments

Question 14

What two fragments form a complex that is a c3 convertase? (Classical)

Answer 14

C2a and c4b

Question 15

How is the lectin pathway activated?

Answer 15

Acute phase protein called mannose binding lectin that is structurally similar to c1q

Question 16

What is the difference between c1 q and mannose binding lectin?

Answer 16

Mannose binding lectin binds directly to microbial mannose residues but c1q binds to FC regions

Question 17

What mannose binding lectin associated proteins activate c2 and c4?

Answer 17

Masp-1 and masp-2

Question 18

What does c3b do to trigger the alternative pathway?

Answer 18

It binds to microbes and to another protein called factor B.

Question 19

In the alternative pathway what does factor B do?

Answer 19

It splits into fragments and joins with another fragment called p. Forms 3bBbp which is another c3 convertase

Question 20

What else does c3b bind to?

Answer 20

It binds to c3 convertAse which changes its substrate specificity to C5. C5 b is starting point of the membrane attack pathway

Question 21

What does c5b stick to?

Answer 21

The lipid membrane surface of a microbe

Question 22

What happens after c5b binds?

Answer 22

C6 and c7 join followed by c8 that inserts itself into the membrane followed by 12-14 copies of c9 that form a tubular structure with hollow centre - microbe punching hole that destroys microb

Question 23

What are phagocytes?

Answer 23

Macrophages already present in tissue

Question 24

What happens when a microbe binds to a PRR on a phagocyte

Answer 24

This triggers the phagocyte to release cytokines and lipid mediators but also triggers process of phagocytosis.

Question 25

What is a phagosome?

Answer 25

Vesicle formed by the process of phagocytosis

Question 26

What are lysosomes and what are their function in phagocytosis?

Answer 26

Lysosomes are vesicles of lytic enzymes found in cytoplasm. They bind to phagosome and release contents onto surface of the microbe.

Question 27

How are reminants of a microbe removed from the cell

Answer 27

By exocytosis.

Question 28

What is opsonisation?

Answer 28

Coating microbes in molecules of the immune system such as C-reactive protein and mannin binding lectin

Question 29

How are parasites destroyed?

Answer 29

Killed extracellularly by eosinophils that release digestive enzymes from stored granules

Question 30

What receptors do eosinophils ave?

Answer 30

FC and co olé net receptors. IgG receptors and IgE receptors once activated

Question 31

True or false: mast cells kill microbes?

Answer 31

False. They do not kill anything. They promote inflammation

Question 32

What is the benefit of inflammation?

Answer 32

Allows cells and molecules to infiltrate infected tissues

Question 33

What FC receptor do Mast cells have?

Answer 33

IgE FC receptor. They are coated n a layer of IgE

Question 34

IgE is important for the activation of what two cells?

Answer 34

Mast cells and eosinophils

Question 35

What two ways can mast cells be activated?

Answer 35

By cross linking of antigen to two or more IgE on cell surface or by binding of c3b or c5a to complement receptor on mast cell

Question 36

What do mast cells contain?

Answer 36

Granules packed with inflammatory mediators such as histamine and heparin

Question 37

Upon activation what else do mast cells produce?

Answer 37

De novo production from arachidonic acid of leucotrines and prostaglandins - released more slowly

Question 38

What do prostaglandins do?

Answer 38

They increase blood flow to infected area and chemotaxis (summon white blood cells)

Question 39

6 stages of inflammation

Answer 39

1) vasodilation 2) leucocyte adhesion 3) vascular permeability 4) chemotaxis of leucocytes 5) immobilisation 6) activation

Question 40

What are the two types of adhesion molecules that help to stick leucocytes to endothelial cells

Answer 40

Selectins and integrins

Question 41

Explain the capture and roll stage

Answer 41

Interaction of leucocytes with selectin on endothelial,cells causes movement to slow down

Question 42

Explain activation and flattening?

Answer 42

This is the second interaction of leucocytes with integrins which allows then to bind very strongly to the endothelial cell surface.

Question 43

Explain extrarasation?

Answer 43

Movement of leucocyte across endothelial cell surface - squeezed between endothelial cells

Question 44

After extrarasation what do they leucocytes do?

Answer 44

They move through the tissue in a directional fashion towards the infection (chemotaxis!)

Question 45

How do macrophages improve chemotaxis?

Answer 45

By producing chemoattractants that form a concentration gradient.

Question 46

What do the chemoattractants do to leucocytes?

Answer 46

Causes formation of integrins on end closest to the chemoattractants - improving connection with tissues and looses connection at other end - moves towards infection

Question 47

What also happens as part of acute phase response (inflammatory response)

Answer 47

Fever Leucocytes is Acute phase protein release from liver