Principles - Innate Immune System 1) Proteins

Question 1

What produces acute phase proteins?

Answer 1

liver

Question 2

What do acute phase proteins do?

Answer 2

mediate inflammatory response
Activate macrophages
Influence chemotaxis
Act as opsonins
Role in tissue repair and remodelling

Question 3

What is C reactive protein?

Answer 3

acute phase protein which acts as opsonin for phagocytes and facilitates binding of complement proteins
Levels rise dramatically in response to infection

Question 4

What is a normal level or CRP?

Answer 4

<5mg/l

Question 5

What are cytokines?

Answer 5

diverse collection of solubule proteins and peptides which modulate behaviour of cells at low concentrations

Question 6

What are the names of the cytokine families?

Answer 6

interferons, interleukins, colony stimulating factors, chemokines (and others)

Question 7

What are interferons important in?

Answer 7

limitation of viral infections

Question 8

What are interleukins?

Answer 8

produced by T cells, these direct cells to divide or differentiate

Question 9

What is interleukin 2 important for?

Answer 9

T cell differentiation and activation

Question 10

What are colony stimulation factors for?

Answer 10

directing the division or differention of bone marrow stem cells e.g act on myeloid cells

Question 11

What are chemokines for?

Answer 11

direct movement of cells in the body

Question 12

When is TNFa formed?

Answer 12

during the acute phase response, important in inflammation

Question 13

What can TNFa activate?

Answer 13

endothelial cells

Question 14

How many proteins does the complement system consist of?

Answer 14

about 30

Question 15

Where are complement proteins produced?

Answer 15

liver

Question 16

When does precursor A become an active enzyme?

Answer 16

when cleaved

Question 17

Is the complement system involved in innate or acquire immune system?

Answer 17

both

Question 18

What is lupus?

Answer 18

an immunopathological disease which is the result of problems with the complement system function

Question 19

What does C3 deficiency result in?

Answer 19

repeated deep seated bacterial infections

Question 20

What is C5 cleaved to?

Answer 20

C5a and C5b

Question 21

How many pathways are there of complement activation?

Answer 21

3

Question 22

Which complement proteins are involved in chemotaxis?

Answer 22

C5a and C3a

Question 23

Which complement proteins are involved in opsonisation and cell activation?

Answer 23

C3b

Question 24

What are the names of the 3 pathways in complement activation?

Answer 24

Classical, Lectin and Alternative

Question 25

What activates the classical pathways?

Answer 25

antibodies

Question 26

What happens in activation of the classical pathway?

Answer 26

antibodies (IgG or IgM) bind to C1, leading to a conformational change in c1

Question 27

What is the order in which the proteins are activated in the classical pathway?

Answer 27

c1, c4, c2, c3

Question 28

What is the classical pathway particularly important for?

Answer 28

clearing bacterial infection | protection against autoimmunity

Question 29

What happens in the Lectin Pathway?

Answer 29

Lectin binds specifically to carbohydrates, whihc bind to Mannose-Binding Lectin

Question 30

What does the Lectin Pathway bypass the need for?

Answer 30

antibodies

Question 31

What do all 3 pathways lead to being activated?

Answer 31

c3

Question 32

What occurs in the Alternative Pathway?

Answer 32

There is a spontaneous hydrolysis of c3 and binding of c3 to bacterial cell wall components, resulting in c3 being cleaved into active fragments

Question 33

What is the alternative pathway dependant on?

Answer 33

activator surfaces (NOT the adaptive immune response)

Question 34

What are examples of bacterial cell wall components c3 is bound to in the alternative pathway?

Answer 34

lipopolysaccharide of gram negative bacteria | teichoic acid of gram positive bacteria

Question 35

What is the alternative pathway vital for?

Answer 35

protection against meningococcus and other encapsulated bacteria

Question 36

What is the major amplification step in the complement cascade?

Answer 36

activation of c3

Question 37

What does the activation of c3 trigger?

Answer 37

formation of final common pathway, complements c5-9 assemble to form the membrane attack complex

Question 38

What does the membrane attack complex lead to?

Answer 38

osmotic cell lysis

Question 39

What happens to C3a?

Answer 39

released into interstitium, is involved in increasing vascular permeability and mediating inflammation

Question 40

What does C3b do?

Answer 40

Is an opsonin - coats bacteria and leads to phagocytosis Promotes specific antibody formation by plasma cells Dissolve the antibodies that trigger the cascade

Question 41

How can the complement system be regulated by biochemical properies of complement components?

Answer 41

Only cleaved proteins are active | and these have a very short half life

Question 42

How can the complement system be regulated by complement inhibitors?

Answer 42

``` Soluble inhibitors (C1 inhibitor, Factor 1, Factor H and c4 binding protein) Inhibitors bound to cell membranes (CD59 and DAF) ```

Question 43

What does CD59 do?

Answer 43

prevents insertion of membrane attack complex

Question 44

What does DAF do?

Answer 44

competes for C4 fragments

Question 45

Who are complement deficiences most common in?

Answer 45

Asian and Middle Eastern populations

Question 46

What are complement deficiences most commonly?

Answer 46

alternative pathway and final common pathway deficiencies