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SEM1 BIOSCIENCE > Case 6 > Flashcards

Case 6 Flashcards

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1
Q

The cytokine that causes T cells to commit to the Th2 lineage in TI hypersensitivity reaction is…

A

IL4

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2
Q

What antibody switches class during TI hypersensitivity?

A

IgG - IgE

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3
Q

Describe the positive feedback loop of IL4 production

A

IL4 causes Th2 cell stimulation
Th2 cells cause increased IgE
increased IgE caused more FCE-mast cell binding
More degranulation and IL4 release

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4
Q

What mast cell receptor does IgE bind?

A

FCE receptor

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5
Q

What is crosslinking?

A

When 2 or more IgE antibodies are bound to FCE receptors on mast cells. Antigen binding activates receptors

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6
Q

How does mast cell degranulation occur?

A

FCE receptor activation

Ca2+ influx

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7
Q

What type of receptor is FCE?

A

Lyn tyrosine kinase

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8
Q

What are the contents of degranulate?

A 
IL4
IL5
Leuokotrienes
Histamine
Prostaglandins
PAF
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9
Q

What are the functions of the components of degranulate?

A

IL4+5- chemokines
Histamine- vasodilation/bronchoconstriction
PAF+prostaglandins- inflammation

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10
Q

From what stem cells do mast cells arise?

A

Myeloid progenitor cells

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11
Q

What is another name for type II hypersensitivity reaction?

A

Cytotoxic hypersensitivity

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12
Q

What leukocytes are attracted to the area following degranulation?

A

Neutrophils and eosinophils

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13
Q

What is the antibody mediator of TII hypersensitivity?

A

IgG

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14
Q

TI hypersensitivity is a misrecognition of what type of pathogens?

A

Extracellular

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15
Q

To where is the antigen bound in a TII hypersensitivity reaction?

A

Cell membrane of a self cell

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16
Q

Outline the effector mechanism of TII hypersensitivity

A 
B cells secrets IgG in response to antigen
antigen also binds self cell membrane
C1 complement protein binds IgG
Complement activated
inflammatory response
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17
Q

What is the timeline of TII hypersensitivity

A

mins-hours

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18
Q

examples of TI hypersensitivity reactions are…

A

asthma
hay-fever
anaphylaxis

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19
Q

examples of TII hypersensitivity reactions are….

A

Penicillin rash

rheumatoid arthritis

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20
Q

Another name for TIII hypersensitivity is…

A

Immune complex reaction

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21
Q

TIII involves an immune response mounted by which antibody?

A

IgG

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22
Q

What molecules make up an ‘immune complex’?

A

Free antigen and antibody

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23
Q

What conditions are favoured by a TIII hypersensitivity reaction?

A

Excess of antigen in relation to antibody

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24
Q

Where does the immune complex reaction take place?

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A

Vascular endothelial space

25
What does a TIII hypersensitivity reaction lead to?
Complement acitivation | Inflammation
26
What is the timescale of TIII hypersensitivity?
3-8 hours
27
Examples of TIII hypersensitivity are...
Serum sickness | Lupus
28
TIV hypersensitivity is driven by a ..... cell response
Th1 cell
29
What cytokine cause Th1 cell lineage commitment?
IL12
30
What effector cytokines are released by Th1 cells in TIV hypersensitivity?
IL2 and IFNy
31
What is the function of IL2? (TIV)
stimulation of Th1 lineage- hence increases allergic response
32
What is the function of IFNy? (TIV)
activates and mobilises macrophages
33
What effect does macrophage mobilisation have ? (TIV)
IL1 and TNFa release | inflammatory response
34
What is an allergen:hapten complex?
complex formed in epidermis | leads to APC (lagerhans/dendritic cell) phagocytosis
35
Following phagocytosis and migration to the lymph nodes, APCs display antigen in context of what?
MHC class II
36
What is the co-receptor stimulatory signal needed for T cell activation? (TIV)
CD28:CD80
37
What is the mediator of a TIV hypersensitivity reaction?
T cells (specifically Th1)
38
What are the effector cells of a TIV hypersensitivity reaction?
Macrophages | secrete IL1 and TNFa
39
Some examples of TIV hypersensitivity are
atopic dermatitis scabies tuberculin skin test
40
What type of receptor is the histamine receptor?
GPCR
41
What cytokine is elevated in AD sufferers and thought to be responsible for the eczema itch?
IL31
42
What lineage of T cells more commonly produce IL31?
Th2
43
What are the main functions of IL31?
cell mediated immunity | itch receptor binding
44
Ichtyosis vulgaris shows what inheritance pattern? What gene is there a defect in?
Autosomal dominant | Filaggrin mutation
45
What are the triggers and drivers of AD?
triggers- allergens | drivers- immune sensitivity/skin barrier defects
46
What are the two main inherited skin barrier defects?
Filagrin | Claudin
47
What are the functions of the filagrin protein?
``` Keratinocyte maturation (cytoskeleton remodelling) Amino acid release (water retention) ```
48
What are the main functions of the claudin protein?
Formation of tight intercellular junctions between keratinocytes
49
What is the result of mutations in filagrin and claudin genes?
Skin barrier defects | Increased allergen penetrance
50
What is the mechanism of action of corticosteriods?
Increase lipocortin/annexin expression Annexin inhibits phospholipase A2 (arachidonic acid pathway) No prostaglandins produced Inflammatory response suppressed
51
What is the consequence of long term corticosteriod use?
systemic distribution -ve feedback on hypothalamic axis adrenal cortex suppression of cortisol release Cushings syndrome
52
emollients work via...
creation of a barrier that is inpenetrable to allergens
53
atopic dermatitis is a combination of both decreased skin barrier function and....
increased immune hypersensitivity
54
induration 72 hours following the mantoux test is indicative of a....
positive result | previous TB exposure
55
If a pt has had no previous TB exposure, why is the mantoux test result negative?
phagocytes can clear the injected tuberculin before the adaptive immune arm can mount a response
56
a negative mantoux test result despite previous TB vaccination is likely to indicate...
immunodeficiency
57
What is the role of TSLP in ezcema?
Promotes a Th2 enviroment (as well as Th1) Causes histamine release More inflammation Increased skin barrier function
58
What are the symptoms of cushings syndrome?
abdominal obeseity hypertension moon face

SEM1 BIOSCIENCE (9 decks)

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