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*Haematology + Immunology > Immunology 3 - Hypersensitivity > Flashcards

Immunology 3 - Hypersensitivity Flashcards

(63 cards)

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1
Q

What are CD8+ cells?

A

T killer cells

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2
Q

What are CD4+ cells?

A

T helper cells

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3
Q

What is Type 1 hypersensitivity reaction?

A

Allergy/immediate hypersensitivity

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4
Q

Allergies are mediated by what?

A

IgE

Hypersensitive T helper cells

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5
Q

What are the phases of type 1 hypersensitivity?

A

Sensitisation Phase

Reaction phase

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6
Q

What is the atopic triad?

A

Atopic dermatitis
Atopic asthma
Allergic rhinitis

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7
Q

What is atopic dermatitis?

A

Eczema

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8
Q

What is the pathophysiology of atopic dermatitis?

A

Degranlation of basophils + mast cells in response to sensitised IgE
“leaky” skin lets allergen in and water out

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9
Q

How are allergies investigaed?

A

Skin testing
Patch testing
Serum Tryptase

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10
Q

How are allergies treated?

A

Antihistamines
Corticosteroids
Adrenaline
Allergen avoidance

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11
Q

What blood antibodies do type A blood individuals have in their plasma?

A

Anti B

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12
Q

What blood antibodies do type O blood individuals have in their plasma?

A

Anti-A and anti-B

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13
Q

What is a hypersensitivity reaction?

A

Excessive immune response to an antigen that causes harm

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14
Q

What pathogens are associated with hypersensitivity reactions?

A

Influenza - cytokine storm

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15
Q

How does Influenza cause hypersensitivity reaction?

A

Cytokine storm
Cytokines attract leukocytes and trigger vascular changes
Hypotension and coagulation
Cytokines can spill into systemic circulation

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16
Q

How can dust trigger hypersensitivity?

A

Dust can mimic parasites and stimulate an antibody response

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17
Q

How do small molecules trigger hypersensitivity?

A

Act as haptens - bind to proteins and elicit immune response

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18
Q

Type 1 hypersensitivity is mediated by what?

A

Immediate response by IgE

Mast cells, Eosinophil degranulation

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19
Q

What is a Type 2 hypersensitivity reaction?

A

Previous exposure causing antibody generation

Reaction on SECOND exposure

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20
Q

What is a Type 3 hypersensitivity reaction?

A

Immune complex

Like type 2 but takes hrs

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21
Q

What is a Type 4 hypersensitivity reaction?

A

2-3 day delayed hypersensitivity

- autoimmunity associated

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22
Q

Type 2 hypersensitivity is mediated by what?

A

IgG

Complement, phagocytes

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23
Q

Type 3 hypersensitivity is mediated by what?

A

IgG

Complement, neutrophils

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24
Q

Type 4 hypersensitivity is mediated by what?

A

T-cells

Macrophages

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25
Outline the pathway of Type 1 hypersensitivity
Th2 cells release IL-4 IL4 stimulates B-cells to release IgE IgE binds to the allergen
26
What are the typical atopic symptoms?
``` Anaphylaxis Angioedema Urticaria Rhinitis Asthma Eczema ```
27
Peanut allergy is associated with which proteins?
Ara h2 - stable protein | Ara h8 - unstable
28
Which peanut protein is associated with cross-reactivity?
Ara h8
29
What allergen is associated with penicillin?
beta-lactam
30
What is the role of filaggrin in allergies?
Expressed by keratinocytes Maintains epithelial barriers (moisture and pH) Polymorphisms in Filaggrin associated with allergy
31
How does the time of allergy development affect allergies?
Developing an allergy whilst young increases the risk of developing another
32
What is the hygiene hypothesis?
Increase in allergies in developing world caused by reduced early exposure to microorganisms
33
Outline anaphylaxis?
Mast cells produce prostaglandins and leukotrienes This causes vasodilation and vascular permeability Fluids shift from vascular to extravascular space This causes a severe BP drop Histamine release in skin causes swelling
34
What pathways of mast cells cause prostaglandin and leukotriene release?
Cyclooxygenase | Lipoxygenase
35
Outline Allergic rhinitis
Allergens stimulate mast cells in nasal mucosa Vasodilation and oedema causes nasal stuffiness Leukotrienes cause mucus secretion
36
What is the affect of leukotrienes on the lungs?
Smooth muscle contraction leading to reduced airflow | This causes wheeze
37
How are allergies treated?
``` Desensitisation (immunotherapy) B2-adrenergic agonists Epinephrine Antihistamines Anto-leukotrienes Corticosteroids ```
38
How do B2-adrenergic agonists work?
(salbutamol) | Prevents bronchial smooth muscle contraction
39
How does Epinephrine work?
Stimlates alpha and beta adrenergic receptors | Increase blood pressure and decrease vascular permeability
40
How do antihistamines work?
Block histamine receptors in skin, nose and mucus membranes
41
What is Type 2 hypersensitivity?
Antibody mediated hypersensitivity IgG or IgM reacting with antigen on cell surface Causes immune mediated haemolysis
42
Anti B and Anti A antibodies are which type of antibodies?
IgM
43
What is Alloimmune haemolysis?
Rhesus antigen | IgG crosses placenta and causes haemolytic disease in SECOND child
44
What are the main types of Immune mediated haemolysis?
Autoimmune Alloimmune Type 2 autoimmune
45
What is Goodpasture's syndrome?
Type II Autoimmune Hypersensitivity Against Solid Tissue | IgG autoantibodies bind to long and glomeruli - inflammatory response
46
What is the mechanisms of penicillin allergy?
Penicillin binds to proteins on RBC surface - acts as hapten Causes that RBC to be destroyed by FcR on splenic macrophage
47
What mutation is associated with Graves Disease?
HLA allele DR3
48
What is Type 3 hypersensitivity?
Immune complex disease - take time to form | IgG mediated
49
What is required for antigens to form complexes?
Antigens must be polyvalent | Ratio of antibodies:antigens is vital
50
How are complexes cleared?
Complement Receptor 1 transfers complexes to phagocytes
51
Failure of complex clearance leads to what?
Activation of the innate immune system (mast cells and platelets)
52
What is Immune complex disease of the kidney?
Glomerulonephriits - immune complexes form in epithelial lining causing infiltrate
53
What are the mechanisms for immune damage of the glomerulus?
Autoantibodies against the glomerular basement membrane (Goodpasture's) Immune complex deposits in the glomerulus (Lupus)
54
Outline type 4 hypersensitivity?
Slowest - T-cell mediated Dendritic cells with antigens migrate to lymph nodes > Present to T cells T cell clones proliferate and migrate to site of inflammation TNF secreted by Macrophages and T cells and stimulate damage
55
RA is what type of hypersensitivity?
Type 4 | Th1, Th17 and TNF mediated
56
What antigens drive RA?
Citrullinated proteins (arginine > citrulline
57
Outline the pathophysiology of RA?
Citrullinated proteins act as antigens which are recognised by T and B cells, these produce antibodies (Anti-cyclic citrullinated peptide antibodies) Synovium infiltrated by T(h1,17) cells, macrophages TNF and IL-17 activate neutrophils and osteoclasts, creating erosions
58
What are the risk factors for RA?
Smoking HLA-DR4 Porphyromonas infections
59
Outline the pathophysiology of MS?
Th1, 17 cells and macrophages develop inflammatory lesions of the CNS Myelin loss causes neurological symptoms Recovery between attacks Chronic disability due to AXONAL loss
60
Name 3 T-cell mediated delayed hypersensitivity (type 4) conditions?
``` RA MS T1DM IBD Psoriasis Coeliac ```
61
How is delayed hypersensitivity treated?
``` Anti-inflammatory drugs NSAIDS, Corticosteroids Anti-TNF Anti-IL-6 B-cell antibodies Immunosuppressants ```
62
Name 3 type 3 hypersensitivity conditions?
Farmer's lung Post-streptococcal glomerulonephritis Lupus
63
Name 3 type 2 hypersensitivity conditions?
Graves' Disease Blood transfusion reactions Haemolytic disease of the newborn Drug-induced haemolysis

*Haematology + Immunology (22 decks)

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