I&d Complement, Phagocytosis And Inflammation

Front 1

Complement is a _______ system

Back 1

cascade

Front 2

How many cascade systems of molecules are present in plasma? What are their names?

Back 2

Four. Complement, clotting, fibrinolytic and kinin

Front 3

What do cascade systems respond to? What to do they induce?

Back 3

Respond to tissue damage, induce inflammation (Complement most important in relation to infection)

Front 4

Complement is the most important cascade system in relation to...

Back 4

...infection

Front 5

What are the main roles of the cascades other than complement?

Back 5

Tissue repair

Front 6

What is a cascade?

Back 6

An entire series of reactions which occurs as a result of a single trigger reaction or compound

Front 7

What does activation of the complement cascade system result in? (3)

Back 7

Inflammation
Enhanced Phagocytosis
Cell lysis

Front 8

What does the complement cascade do? (Also, where does its name originate from?)

Back 8

It 'complements' (enhances) the ability of antibody to dispose of microorganisms

1757121110

Front 9

There are inhibitors of complement. What is the point of these?

Back 9

They prevent complement from damaging own cells

Front 10

What is the central component of complement?

Back 10

C3 - it is a major serum protein (the clear liquid that separates from blood on clotting)

Front 11

What leads to activation of C3?

Back 11

The enzymatic splitting of it

Front 12

If activation of C3 occurs on the surface of a bacterial cell, most of the C3 is left in the form of the cleavage fragment ___. The function of ___ is to...

Back 12

C3b. Mark out the bacterium for phagocytosis (phagocytic cells have receptors that recognise and attach to C3b)

Bacteria is now said to be OPSONISED

Front 13

What is opsonisation?

Back 13

The process by which bacteria are altered in such a manner that they are more readily and more efficiently engulfed by phagocytes.

E.g. C3b attachment to bacteria is an example of opsonisation

Front 14

Other than to be a marker for phagocytes, what is the other use for C3b?

Back 14

To act as a focus for other complement components (C5,6,7,8,9) to collect and form into small pores that puncture the cell membrane and make it leak --> Leading to death (lysis)

Front 15

Lysis by membrane attack complex is less important than C3b attachment, normally. However, for which species is this not true?

Back 15

With the Neisseria species

Front 16

What is the function of C3a? What does it combine with to achieve this?

Back 16

Its function is to promote inflammation - achieved by working together with C5a

Front 17

How do C3a and C5a promote inflammation?

Back 17

By attracting neutrophils and activating mast cells

Front 18

How does attraction of neutrophils and active mast cells cause inflammation?

Back 18

Local vascular permeability increases

Front 19

What happens as a result of inflammation?

Back 19

Neutrophils, monocytes, antibodies and more complement flow into the tissues

Front 20

Collectively, C3a and C5a are known as...

Back 20

Anaphylatoxins (Any of several toxic substances that trigger anaphylaxis (An acute allergic reaction to an antigen))

Front 21

What are the three ways cleavage of C3 can occur?

Back 21

ALTERNATIVE PATHWAY: Spontaneously on the surface of cells (e.g. bacteria) with help from factors B, D and Properdin. Produces C3bBb which converts C3 into C3a and C3b

CLASSICAL PATHWAY: Requires *presence of antibody*.
C1q, C1r and C1s bind to antibody attached to pathogen --> Activation of C4 and C2 forms classical pathway C3 convertase (C4b2a) which cleaves C3 into C3a and C3b

LECTIN PATHWAY: Antibody *independent*. Triggered by microbial surface sugar recognition by MBL and by MASP-1 and-2

Front 22

What helps C3 cleave on the surface of some cells like bactera?

Back 22

Factor B, Factor D, properdin. Produces enzyme C3bBb (alternative pathway C3 convertase)

Front 23

What does the classical pathway of cleavage of C3 require?

Back 23

Antibody

Front 24

Describe the lectin pathway

Back 24

Mannose-binding lectin binds to mannose residues on carbohydrate or glycoprotein components of microorganisms including bacteria

MBL forms a complex with MASP-I (Mannan-binding lectin-Associated Serine Protease) and MASP-II, two protease zymogens.

MASP-I and MASP-II are very similar to C1r and C1s molecules of the classical complement pathway

When the carbohydrate-recognising heads of MBL bind to specifically arranged mannose residues on the phospholipid bilayer of a pathogen, MASP-I and MASP-II are activated to cleave complement components C4 and C2 into C4a, C4b, C2a, and C2b.

C4b and C2a combine on the surface of the pathogen to form C3 convertase (C4b and C2a --> C4b2a), while C4a and C2b act as chemoattractants.

Front 25

Where are receptors for complement found? (3)

Back 25

Phagocytes
Erythrocytes
B lymphocytes

Front 26

How does the Epstein-Barr virus infect?

Back 26

It uses receptors for complement on B-cells to attach to them and infect, causing glandular fever.

Front 27

What attracts phagocytes to where they are needed?

Back 27

Chemotactic gradients (complement is important in regard to this, as well as microbial and other immunological molecules)

Front 28

How does the phagocyte attach to the bacterium?

Back 28

*Pattern recognition receptors* (PRRs) on the surface pf phagocyte recognise *pathogen-associated molecular patterns* (PAMPS) on the surface of the microbe.

Binding is enhanced if complement or antibody has coated the microbe, and they are recognised by corresponding complement receptors and receptors for antibody (Fc receptors) on the phagocyte

Front 29

What are Fc receptors?

Back 29

Receptors on phagocytes that recognise antibody on a bacterium.

Bacterium with antibody on them are easier to engulf

There are also 'complement' receptors

Front 30

When the bacterium is taken into the phagocyte, it is said to be in a...

Back 30

...phagosome

Front 31

What does the lysosome destroying the bacteria contain?

Back 31

Oxygen free radicals and granules possessing toxic proteins

Front 32

The fused phagosome and lysosome is referred to as a...

Back 32

...phagolysosome

Front 33

When a phagocyte engulfs a microbe there us usually a __________ _____ during which there is generation of microbicidal...

Back 33

'respiratory burst'. Generation of microbicidal oxygen free radicals (inc. superoxide - leading to production of hydrogen peroxide and hypochlorite)

Front 34

What are the ways of non-oxidative killing? (4)

Back 34

Lysozyme
Defensins (produced in the milk of the mother)
Lactoferrin
Protease

Front 35

What are the oxidative killing methods?

Back 35

Reactive oxygen intermediates (O2- (superoxide), H2OH, OH' (hydroxyl radical) OCL- (hypochlorite))

Front 36

What are the nitric oxide-relating killing methods?

Back 36

Reactive nitrogen intermediates

Front 37

Where are mast cells found?

Back 37

CT, skin, lung, intestine

Front 38

What is the term used when mast cells release the contents of their granules?

Back 38

They are said to 'degranulate'

Front 39

What does degranulation of mast cells achieve?

Back 39

It helps initiate the acute inflammatory response

Front 40

What do the granules in mast cells contain a lot of? What does it act on?

Back 40

Histamine. Acts on blood vessels and smooth muscle

Front 41

What does histamine release cause?

Back 41

Increased blood flow to area and process of damage-limitation and control of infection begins.

Front 42

Which complement components stimulate mast cells?

Back 42

C3a and C5a and specific antigen (when sensitised by IgE antibody)

Front 43

Mast cells are involve with innate/adaptive immunity

Back 43

Both

Front 44

Blood basophils are very similar/different to mast cells

Back 44

Similar

Front 45

When can inflammatory response be dangerous?

Back 45

When it occurs in a limited area like the airways or brain, or if it leads to breakdown of vital tissue (e.g. burst appendix)

Front 46

What is the intention of inflammatory response?

Back 46

Restricting infection, limiting tissue damage and initiating repair

Front 47

Back 47

.

Front 48

What part of complement triggers mast cells to release inflammatory mediators?

Back 48

C3a and C5a

Front 49

What part of complement is a chemotacic factor for neutrophils and macrophages?

Back 49

C5a

Front 50

What complement parts trigger lysis of cells? (By punching holes in cell membranes)

Back 50

C5b - 9

Front 51

Which part of complement causes opsonisation?

Back 51

C3b

Front 52

Which part of complement helps with transport of immune complexes?

Back 52

C3b

Front 53

RBCs have complement T/F

Back 53

T

Front 54

RBCs can take immune complexes (Erythrocytes with complement and antibody on them) to which organs?

Back 54

The spleen and liver

Front 55

Prokaryotes often have which sugar at the end of their cell membrane chains? Why is this important?

Back 55

Mannose. Used for Mannose Binding Lectin (MBL) - important in phagocytosis

Front 56

What is the C3 convertase of the classical pathway?

Back 56

C4b2a

Front 57

What is the C3 convertase of the Lectin pathway?

Back 57

C4b2a

Front 58

What is the C3 convertase of the alternative pathway?

Back 58

C3bBb

Front 59

What happens to C3 if left on its own?

Back 59

It will slowly autocatalyse.

Front 60

How many molecules of C9 combine when doing cell lysis?

Back 60

7

Front 61

What is an example of something that PAMP recognises?

Back 61

Exposed mannose

Front 62

What does a line above C3bBb mean?

Back 62

That it is active