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Allergy and the Immune Response to Parasites Flashcards

1
Q

Why are multicellular parasites difficult to eradicate? (3)

A
  1. They are less antigenic
  2. Cannot be engulfed
  3. Have a long life-span
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2
Q

What are the functions of IL-4? (2)

A
  1. Induce differentiation of TH2 cells
  2. Induce claSs-switching to IgE
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3
Q

IgE binds to what receptor on mast cells, basophils, or activated eosinophils?

A
  • FcεRI (R1) - high affinity
  • FcεRII (R2) - low affinity
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4
Q

How long can IgE remain in serum after binding to R1 or R2?

A
  • Months to years
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5
Q

The R1 receptor is a tetramer where the α-chain is responsible for _____, and the β, γ, and γ chins are responsible for _____

A
  • Binding IgE
  • Signaling
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6
Q

B-cells have 50,000 to 100,000 receptors that are ______, whereas mast cells with bound IgE can have >500,000 R1 receptors that are _______

A
  • Monospecific
  • Polyspecific
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7
Q

Mast cells secrete the remodeling enzyme ______ in mucosal tissue and ______ in connective tissue.

A
  • Tryptase
  • Chymotryptase
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8
Q

When a pathogen binds TLR, it secretes IL-4 and IL-13 to amplify _____ and IL-5 for _____.

A
  • TH2 response
  • Eosinophil production/activation
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9
Q

What are the preformed mediators contained in the granules of mast cells?

A
  1. Tryptase (or chymotryptase)
  2. Histamine and/or heparin
  3. TNF-α
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10
Q

What are the biological effects of histamine and heparin?

A
  1. Poison parasites
  2. Increase vascular permeability
  3. Cause smooth muscle contraction

Overall triggers inflammation

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11
Q

What are the biological effects of TNF-α stored in granules of mast cells?

A
  1. Promote inflammation
  2. Stimulate cytokine production by many cell types
  3. Activates endothelium (induces expression of adhesion molecules)
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12
Q

What are mast cell mediators are synthesized after degranulation?

A
  1. IL-4 and IL-13
  2. IL-3, IL-5, GM-CSF
  3. CCL13
  4. Leukotrienes and prostaglandins
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13
Q

Where are the following histamine receptors located? H1, H2, H3, and H4

A
  • H1 - vascular endothelial cells, smooth muscle cells, heart, and brain
  • H2 - vascular endothelium and GI
  • H3 - CNS
  • H4 - Bone marrow
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14
Q

Prostaglandins and leukotrienes are formed from what common precursor present in cell membranes?

A

Arachidonic acid

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15
Q

What are the functions of prostaglandins in smooth muscle, endothelial cells in blood vessels, and neutrophils?

A
  • Smooth muscle - constriction
  • Endothelial cells - vasodilation
  • Neutrophils -chemotaxis
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16
Q

True or false. Aspirin blocks prostaglandin and leukotriene synthesis to help reduce inflammation.

A

False. It only blocks prostaglandins, not leukotrienes

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17
Q

What is the biological effect of CCL13 expressed by mast cells after degranulation?

A

Attraction of monocytes, macrophages, and neutrophils

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18
Q

In the context of IgE, why are mast cells more variable than B cells in terms of their response to antigen

A

Because mast cells bind to different IgE molecules of various specificities for antigen that can be diverse in their structure and biological origin

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19
Q

Which of the following have biological activities in common with histamine but are more potent?

  1. Prostaglandins
  2. Arachidonic acid
  3. Carboxylpeptidases
  4. Heparin
  5. Leukotrienes
A

Leukotrienes - about 100x more potent

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20
Q

Which forms of hypersensitivity reactions are antibody-mediated and which are T-cell mediated

A
  1. Type I: immediate - antibody
  2. Type II: cytotoxic - antibody
  3. Type III: immune complex - antibody
  4. Type IV: Delayed - T-cell mediated
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21
Q

Hypersensitivity reactions occur when an already immune or ______ individual is re-exposed to the initiating substance (allergen).

A

Sensitized

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22
Q

Explain the tenents of the hygiene hypothesis

A
  • Excessive hygiene reduces childhood exposure to pathogens
  • Vaccination reduces developing immune system’s experience in facing natural infections
  • Overreliance on antibiotics to terminate infections
23
Q

Type I hypersensitivities are mediated by ____ in response to allergens and usually occur within minutes

24
Q

What features of inhaled allergens promote priming of TH2 cells that drive IgE response.

A
  • Many allergens are proteases
  • Low molecular weight
  • High solubility
  • High stability
  • Contains peptides that bind to MHC-II
25
What genetic and environmental factors can predispose an individual to type I hypersensitivity? (3)
1. Structural variations in MHC-II enhances presentation of allergen-derived peptides 2. TCR α-locus noncoding variant can enhance T-cell recognition of certain allergen-derived peptides 3. Variations in expression of IL-4
26
Describe the 3 stages of type I hypersensitivity reactions 1. Sensitization 2. Immediate rxn 3. Late-phase rxn
1. Sensitization - first exposure to allergen; IgE binds to mast cells and basophils 2. Immediate rxn - second exposure; allergen triggers cross-linking of IgE and degranulation (~10 minutes) 3. Late-phase - synthesis of prostaglandins and leukotrienes (~8 hours)
27
What are the functions of eosinophils in the late-phase reaction of a type I hypersensitivity reaction?
1. Release toxic granular proteins (tissue injury) 2. Amplify inflammatory response with chemokines, prostaglandins, or leukotrienes
28
When allergens enter the blood, it triggers \_\_\_\_\_\_
Systemic anaphylaxis
29
What are the symptoms of anaphylatic shock?
1. Urticaria 2. Nausea/vomitting 3. Rapid drop in bp due to vasodilation 4. Difficulty breathing 5. Organ damage
30
What are haptens?
Molecules too small to invoke an immune response Ex: penicillin
31
What is meant by “wheal & flare”?
Urticaria and angioedema
32
Inhalled allergens of the UPPER airway leads to \_\_\_\_\_\_
allergic rhinitis of the nasal passages and conjunctiva
33
Inhalled allergens of the LOWER airways leads to \_\_\_\_\_
asthma
34
Desensitization to an allergen involves giving a series of small injections of allergen to mount an immune response. Why does this work?
When allergen enters the blood stream, it then binds to IgG before it can bind to IgE and trigger systemic anaphylaxis.
35
What is the function of Omalizumab (Zolair)?
Anti-IgE monoclonal antibodies used to treat type I hypersensitivity
36
What is the function of Mepolizumab?
* Monoclonal antibody against IL-5 * Inhibits eosinophils
37
\_\_\_\_\_ hypersensitivity reactions involve IgG or IgM against cell structures, resulting in destruction of the cell via complementation, opsonization, or antibody-dependent cellular toxicity (ADCC).
Type II
38
Improper transfusion of blood types (ABO and Rh antigens) results in a ______ hypersensitivity reaction.
Type II
39
What are isohemagglutinins?
IgM antibodies directed against blood group antigens
40
First and subsequent pregnancies of Rh- mothers carrying Rh+ fetus are infused with \_\_\_\_\_, an anti-Rh IgG.
RhoGam
41
Type III hypersensitivity is caused by \_\_\_\_\_
deposition of immune complexes
42
Where are immune complexes most likely to deposit in type III hypersensitivity? (3)
1. Blood capillaries 2. Lung alveoli 3. Kidney Glomeruli
43
The adverse effects of immune-complex deposition are a direct result of _______ and subsequent accumulation of \_\_\_\_\_\_\_
* Complement activation (C3a and C5a) * Neutrophil and platelet infiltration
44
A penicillin allergy would be considered a type ____ hypersensitivity?
Type III
45
What are the consequences to immune complex deposition in the following locations: 1. Blood vessels 2. Basement membranes of kidneys 3. Basement membranes of joints 4. Skin
1. Blood vessels → vasculitis 2. Basement membranes of kidneys → glomerulonephritis 3. Basement membranes of joints → arthritis 4. Skin → urticaria
46
Type IV hypersensitivity reactions are mediated by \_\_\_\_\_
Antigen-specific TH1 cells
47
Type IV hypersensitivity reactions typically occur ____ after exposure to antigen
1-3 days
48
TH1 cells cause damage in type IV hypersensitivity reactions by secreting IFN-γ and TNF-β. What are the consequences of this?
* IFN-γ - activation of macrophages * TNF-β - tissue destruction, macrophage activation, macrophage chemotactic factor
49
A nickel allergy is an example of a type ___ hypersensitivity
Type IV
50
How would a type IV hypersensitivity reaction present histologically?
* Macrophage and T-cell infiltrates * Granuloma formation * “erythema and induration”
51
Contact dermatitis is an example of a type ____ hypersensitivity
Type IV
52
In order for a hapten to trigger contact dermatitis, it must be able to _____ (2)
1. Penetrate the skin 2. Covalently couple with host proteins
53
What are the most common causes of contact dermatitis? (6)
1. Organic chemicals 2. Metals 3. Topical drugs 4. Cosmetics 5. Plant material

Immunology (13 decks)

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