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Basics + innate immunity Flashcards

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1
Q

Describe the flow of lymph in a lymph node

A

Kidney shaped, enter from outside, go through cortical sinus, drain to medullary sinus then out through efferent lymphatic vessel.

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2
Q

Where in the lymph nodes do B cells, T cells, and APC lie.

A

Primary lymphoid follicle - naive B cells
Paracortical area - T cells
Medullary cords - APC

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3
Q

Where do B cells go after activation?

A

Germinal Centers

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4
Q

Where are lymph nodes not found

A

CNS

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5
Q

What organs comprises central lymphoid tissue

A

Bone marrow and thymus

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6
Q

Where is the thymus and how does it grow?

A

Mediastinum, enlarges in childhood, regresses after puberty but continues to function

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7
Q

What is the function of the thymus

A

Maturation of T cells.
CD4/CD8 selection
Deletion of self-reactive T cells via AIRE
MHC class maturation

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8
Q

What are lymphoid tissue in the GI called?

A

Peyer’s patch

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9
Q

Function of the spleen

A

Release lymphocyte when needed, remove cellular debris from blood like RBC.

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10
Q

Describe the recirculation of lymphocytes

A

During inflammation, extravasated fluid drains via lymph circulation, carrying with it antigen and APCs with antigen. This goes to the lymph nodes for presenting to lymphocytes.

If lymphocyte activation occurs, lymphocytes proliferate and leave the lymph nodes to the site of infection.

If not activation occurs, lymphocytes continue circulating round the lymph vessels

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11
Q

Describe briefly the full process of an immune response

A

Pathogen enters circulation, picked up by phagocytes.

Innate immunity activated, complement activation, inflammation cascade initiated.

Pathogen engulfed and presented in lymph node
If match occurs, specific immunity activated and released to site of infection. Antibody production starts and joins the fight.

After infection cleared, phagocytes clean up debris and anti-inflammation begins, resolution.

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12
Q

Characteristics of innate immunity

A 
Rapid 0-4 hours
Non-specific 
No memory 
Common to shared genotype
Comprises cellular and humoral components
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13
Q

Characteristics of adaptive immunity

A

Delayed 3 days

Specific - one antibody one antigen

Humoral and cellular components

Memory allows for remembrance of encountered pathogens, gives rise to immunity and variation between people

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14
Q

Which immunglobulin class lines mucosa?

A

IgA

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15
Q

Fatty acids lining the lungs help in microbial defense - True or false?

A

False. Fatty acids are found on the skin

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16
Q

What are phagocytes in the liver called?

A

Kuppfer cells

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17
Q

Where are alveolar macrophages found?

A

In the lung

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18
Q

What are resident skin phagocytes called?

A

Langerhans cells

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19
Q

Eosinophils are responsible for forming pus - true or false?

A

False - neutrophils do that

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20
Q

What is the function of eosinophils?

A

Defense against large parasites and helminths

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21
Q

How are eosinophils activated?

A

By complement opsonisation

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22
Q

What do dendritic cells do?

A

Phagocytose pathogens
Antigen-presenting cell
Release cytokines to activate inflammatory pathways

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23
Q

What is found inside mast cells?

A

Granules of histamine, prostaglandins, leukotrienes

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24
Q

What activates mast cells?

A

IgE

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25
How are natural killer cells activated?
Surface glycocproteins of virally-infected cells
26
What inhibits activation of NK cells?
MHC class 1 - prevents autolysis
27
Where are perforins found? What is their function
In NK cells Inserts itself into target to create transmembrane pore Forms conduit for lytic enzymes to enter
28
What are the 5 functions of complement
``` Activate inflammatory pathway Opsonise pathogens Form MAC Clear immune complexes Recruit phagocytes ```
29
What is a muramidase?
Lysozyme that splits peptidoglycan wall of some bacteria
30
Describe 2 ways which the innate immune system recognises foreign microbes
"PAMP" - pathogen associated molecular pattern Binds to host cell "pattern recognition receptors" PRR Activates NFkappaB Toll-like receptors (TLRs) - 10 types in humans also leads to activation of NFkappaB
31
What pathways is activated when TLRs and PAMPs are recognised?
NFkappaB
32
What do "CRP" and "MBL" do ?
C reactive protein and Mannose Binding lectin work to opsonise pathogens and fix complement
33
What does IL-1 do?
Causes fever
34
What does TNFalpha do?
Primary pro-inflammatory cytokine
35
Describe interferons
"Interferes" with viral replication, protects cells from viral infections. Activate immune cells like NK cells Upregulates MHC 1 and 2 in infected cell. MHC molecules help to present viral antigen, activating other immune cells like CD8 and CD4 T cells
36
Name the 3 pathways of complement activation
Classical Lectin Alternative
37
What is the common product in the 3 complement pathways
C3 convertase
38
How is the classical pathway activated?
Activated by antibody-antigen complexes and pathogen PAMPs
39
Describe the classical pathway
C1q -> C1s esterase ->C4 + C2 -> C4b2a = C3 convertase
40
What is the C3 convertase made by the classical and lectin pathway?
C4b2a
41
Describe the lectin pathway
MBL AKA ficolin bind to mannose/oligosaccharides activate MASP1 and MASP2 cleave C4 and C2 -> C4a2b
42
What is the c3 convertase made by the alternative pathway
C3bBb, stabilised by properdin to become C3bBbP
43
Describe the alternative pathway
C3 hydrolysed to C3(h2o) + factor B and D become C3(h2o)Bb which is a C3 convertase which then works on C3 to make C3b and c3a. C3b interacts with factor B to become C3bB which interacts with Factor D to become C3bBb which needs to be stabilised by factor P to become C3bBbP = C3 convertase
44
What is c3a involved in?
Proinflammatory signalling and phagocyte recruitment
45
What are the 2 functions of C3b
1) opsonise pathogens | 2) become C5 convertase
46
How is C5 convertase made?
C3b + c4b2a + c3bBb to form c4b2a3b and (c3b)2Bb Both of which are c5 convertases
47
What are the 2 C5 convertases
C4b2a3b and (c3b)2Bb
48
What does C5 convertase do?
Converts C5 to C5a and C5b
49
What does C5b do?
Forms MAC
50
What does C5a do?
Anaphylotoxic proinflammatory signalling molecule
51
How is MAC formed?
C5b + c6 + c7 + c8 forms a complex on the membrane of the target. C9 joins the complex and polymerises itself to form a ring complex, eventually forming a pore which opens the pathogen to the environment, lysing it.
52
What complements are involved in MAC formation?
C5b, c6 c7 c8 and c9
53
What does an anaphylotoxin do?
``` Local inflammation Increased vascular permeability Smooth muscle contraction Induce adhesion molecules Recruit phagocytes ```
54
How does complement clear immune complexes
C3b attaches itself to antigen-antibody complexes, tagged for destruction by phagocytes or attach to RBC for degradation in the spleen
55
Which MHC molecule is commonly lost in virally infected cells?
MHC class I
56
What are the 3 conditions that have to be met for phagocytosis to occur
C3b bind to bacterium (oposnisation) C5a bind to phagocytes (anaphylotoxin activation) Antibody on bacterium bind to Fc receptor on phagocyte
57
What are 5 ways which phagocytes can kill a pathogen
``` Acidification Toxic oxygen derrived products Toxic nitrogen oxides Antimicrobial peptides Enzymes (lysozymes) ```
58
What happens when a NK cell is activated by an infected cell?
Polarisation of granules between nucleus and targets, extracellular release of granules which neutralises target
59
Describe antibody-dependent cellular cytotoxicity (ADCC)
Activation of NK cells by virally infected cells, via antibody-opsonised pathogen
60
What receptor is required for antibody-dependent cellular cytotoxicity (ADCC)
FcGammaRIII AKA CD16
61
What is the function of FcGammaRIII AKA CD16 receptor?
Receive IgG which are bound to virally infected cells, activates NK cells to kill it.
62
NK cells are activated by surface antigen-receptors - true or false?
False, NK cells do not have antigen receptors.
63
What is the role of mast cells in neutrophil recruitment?
Activated mast cells release chemokines which initiaties chemotaxis of neutrophils to site of infection.
64
How do APCs bridge the gap between innate and specific immunity?
APCs engulf pathogens and display their antigens on their surface They travel to lymph nodes and wait for its specific lymphocyte to arrive, activating it, initiating the specific immunity process.
65
Which class of MHC molecule do APCs use to present antigen?
MHC class II
66
What MHC class is used by virally-infected cells to present viral antigens?
MHC class 1
67
Describe the process of viral antigen presentation in an infected cell
Virus enters cell, viral proteins degraded in proteasome, become peptides Antigenic peptides go to rER Antigen associated with MHC I molecules and are transported to the surface where they are presented together.
68
What other roles do macrophages have when not involved in immunity?
Clearing cellular debris | Apoptising damaged cells (cancer prevention)
69
Which CD[][] are expressed by macrophages and function as co-stimulatory molecules?
CD80 and CD86
70
What is the role of fibroblasts in immune response?
Synthesise extracellular matrix and collagen Help in wound healing Also play a role in initiating immune response.

2 Immunology (3 decks)

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