TRAN 1001 > L9 - Complement > Flashcards

L9 - Complement Flashcards

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1
Q

Another name for known antibodies is what

A

antisera

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2
Q

What are the two types of antisera

A

Polyclonal
Monoclonal

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3
Q

Describe polyclonal antisera

A

Mixture of antibodies with different specificities (each have different fab region)

Recognizes various epitopes within the same antigen

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4
Q

Describe monoclonal antisera

A

Mixture of antibodies with the same specificities. All have same antigen binding site

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5
Q

Describe the steps to polyclonal antibody production

A

Animal is inoculated with antigen to induce the production of antibodies

Multiple B cells within the animal react (BCR combines with epitope) and product an antibody

Blood sample is collected from the animal and separated

Plasma that contains many different antibodies that recognize different epitopes on an antigen

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6
Q

What portion of the blood are antibodies found in

A

Plasma (supernatant)

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7
Q

Describe the step to monoclonal antibody production

A

Small animal is inoculated with antigen to induce the production of antibodies

Animal spleen is removed and made into a cell suspension

Spleen cells are fused with myeloma (cancerous plasma) cells to create hybridomas - will grow continuously

Hybridomas are grown in selective media so only they survive

Hybridomas form clone and are screened for the desired antibody

Select clones are cultures to produce antibodies

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8
Q

Why are spleens used for making monoclonal antibodies

A

Spleens make the most B-cells

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9
Q

What are some advantages to polyclonal antibodies

A

Inexpensive to produce
Quick to produce
Easy to store

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10
Q

What are some disadvantages to polyclonal antibodies

A

Variability between batches produced on different animals

Higher potential for cross-reactivity

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11
Q

What are some advantages to monoclonal antibodies

A

High specificity to a single epitope (reduced cross reactivity)

Can produce large quantities

Many clinical and therapeutic applications

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12
Q

What are some disadvantages to monoclonal antibodies

A

More expensive to produce

Longer time required to produce

Greater storage demands

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13
Q

What are some diagnostic clinical applications of monoclonal antibodies (MAbs)

A
  • Typing tissue and blood (HLA, blood group antigens)
  • Identifying pathogens
  • Identifying classes of leukemias and lymphomas
  • Identifying tumor antigens and autoantibodies on tissues
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14
Q

What are some therapeutic clinical applications of monoclonal antibodies (MAbs)

A

Delivering immunotherapy, such as:
Drug delivery to a specific location - we tag the monoclonal antibody with medication and it goes to its epitope
Phagocytosis activation
Complement activation

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15
Q

V briefly - what is the complement system

A

A group of 30+ proteins that help the immune system fight infection

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16
Q

Outline how the Complement system works

A
  • Activated by detecting something foreign
  • Proteins activate each other in a chain reaction (complement cascade)
  • Proteins tag invaders (opsonization)
  • Lyse foreign cells (cytolysis)
  • Guide immune cells to the infection site
  • Increase blood flow (inflammation)
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17
Q

Is the complement system part of the innate or adaptive immune system

A

Innate - is non-specific and has no memory

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18
Q

What are the three distinct pathways by which complement can be activated

A

Classical pathway
Lectin pathway
Alternative pathway

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19
Q

Describe activation of the classical pathway

A

Activated when antibodies bind on a pathogen or target cell

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20
Q

What are the two common proteins that are made by all three of the complement pathways

A

C3 and C5

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21
Q

Describe activation of the lectin pathway

A

Activated when pattern recognition molecules (mannose binding lectin) binds to specific sugar residues (mannose) found on microbial surfaces

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22
Q

Describe activation of the alternative pathway

A

Spontaneous low-level activation (hydrolysis) of C3
Always on - kind of acts like a surveillance system

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23
Q

Describe the binding of the recognition unit of the classical pathway and what happens after (up until the activation unit)

A
  • Antibody binds to antigen on pathogen
  • C1qrs (recognition unit) comes
  • When 2 or more C1q globular heads attach to the bound antibody in its Fc region, this initiated C1, causing a configuration change where C1r becomes enzymatically active
  • C1r then cleaves C1s
  • C1s becomes enzymaticlaly active and cleaves the next set of proteins - C4 and C2
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24
Q

What protein makes up the recognition unit of the classical pathway. What holds it together?

A

C1qrs
Held together by calcium

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25
C1q binds to which part of the antibody
The Fc region
26
When C1r becomes active, what does it do?
Cleaves C1s
27
The activation unit consists of what proteins
C4 C2 C3
28
C1s cleaves C4 into what
C4a and C4b
29
What is the fate of C4a
Floats off and is degraded
30
What is the fate of C4b
Binds to the cell wall of the pathogen
31
C1s cleaves C2 into what?
C2a and C2b
32
What is the fate of C2a
Binds to cell wall of pathogen
33
What is the fate of C2b
Floats off and is degraded
34
What two proteins combine to become C3 convertase
C4b and C2a
35
C3 convertase cleaves what into what
C3a and C3b
36
What is the fate of C3a
Floats off as an anaphylatoxin
37
What is the fate of C3b
Combines with C3 convertase or becomes an opsonin
38
What proteins make up C5
C4b C2a C3b
39
Describe the amplification loop of the classical pathway
One C3 convertase can split up to 200 C3 and C3b can opsonize multiple pathogens
40
What proteins are involved in the membrane attack complex (MAC)
C5 C6 C7 C8 C9
41
C5 convertase cleaves what into what
C5 into C5a and C5b
42
What is the fate of C5a
Floats off and becomes an anaphylatoxin
43
What is the fate of C5b
binds to the pathogen (start of the MAC)
44
Once C5b binds to the pathogen, what follows?
C6, C7,C8 and multiple monomers of C9 also join to form the MAC
45
MAC causes cell damage by which 2 different mechanisms
1. Channel formation (creates a hole) 2. Reordering and re-orientation of membrane molecules (makes membrane leaky)
46
Both the two mechanisms lead to destruction of the pathogen via:
- influx of water into the cell (cell bursts) - Loss of electrolytes from the cell (cell shrinks)
47
What do anaphylatoxins do
Promote inflammation
48
What is the benefit of promoting inflammation?
Eliminates cause of injury, clears out damage cells and begins repair of tissues
49
How does C3a act as an anaphylatoxin (its mechanism of action)
Binds to receptor on mast cells and basophils, releasing the contents of their granules (histamine), which acts on nearby blood vessels to dilate
50
Increased blood flow leads to what symptom in the body
Redness and heat
51
Increased vascular permeability leads to what symptom in the body
Pain, swelling, and difficulty moving that area - Fluid and proteins leak out of the vessel into tissues
52
How does C5a act as an anaphylatoxin (its mechanism of action)
Attracts neutrophils and monocytes to the site of infection via chemotaxis Binds to receptors on neutrophils triggering their activation (increased phagocytosis, release contents of granules)
53
Define margination
Neutrophils cling to the capillary wall So they don't keep moving past the site where they're supposed to be
54
Define Diapedesis
Neutrophils flatten and squeeze out of capillaries
55
T/F Complement is a cell-mediated component of innate immune defenses
False - It is a humoral component of innate immune defenses
56
How does the complement system act as a housekeeping mechanism
It tags apoptotic cells and immune complexes for clearance by innate immune cells
57
What happens if uncontrolled activation of the complement system occurs
Chronic inflammation Tissue damage
58
Deficiencies in complement proteins can do what?
Increase infection risk
59
What disease might cause a decrease in complement proteins
Liver disease
60
Why is the complement system relevant to transfusion medicine
Bc it is a major mechanism behind immune mediated RBC destruction. When RBC antibodies bind to RBC antigens on transfused donor RBCs they can activate the complement cascade
61
Why is complement activation bad after a transfusion
If you're transfusing RBCs, the patient is already anemic. Not helpful if those donor RBCs are getting immediately killed
62
What two antibodies can activate complement
IgG and IgM
63
At what temperature do IgG antibodies bind with epitopes
37 degrees C
64
T/F For complement activation, 2 IgG molecules must be present on an antigen
True
65
At what temperature do IgM antibodies bind with epitopes
21 degrees C
66
T/F For complement activation, 2 IgM molecuels must be present on an antigen
False - just one!
67
What is better at activating complement - IgG or IgM?
IgM because you need less
68
T/F Blood group systems make only one kind of Immunoglobulin and cannot switch
True
69
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