Lecture 19: Allergy Flashcards Preview

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Flashcards in Lecture 19: Allergy Deck (33):
1

an environmental Ag that elicits allergic responses in susceptible individuals. These Ags have little or no intrinsic toxicity

Allergen 

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Clinically adverse reactions to environmental Ags mediateed by acquired immune responses

Allergy

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Allergies are clinically adverse reactions to environmental Ags mediated by acquired immune responses which are marked by:

  • The presence of allergen-specific IgE 
  • Mast-Cells and eosinophils recruitment and/or activation
  • Th2-type of responses and IL-4,IL-5, and IL-13 are key elements 

4

The propensity for developing immediate hypersensitivity reactions to common environmental allergens 

Atopy 

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All allergic disease have what common mechanistic aspects:

  • All result rom harmful immune responses
  • Immune responses are driven by non-infectious Ags
  • Immune responses are all associated with the generation of IgE 

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Allergens are a diverse group of ___ and ___

proteins and glycoproteins

7

Allergens activate the innate immune response by:

  • An intrinsic enzymatic activity 
  • Activation of PRRs 

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Indoor allergens are usually associated with ____

asthma

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Outdoor allergens are usually associated in 

allergic rhinitis

10

Several allergnes have protease activity, which is important why?

may play an role in crossing skin or mucosal barriers

11

Polymorphisms in what genes are known to be involved in allergic disease

  • The ß chain of the high affinity receptor for IgE (FceRIß)
  • The IL-4 gene
  • The HLA-DR alleles
  • the CD14 

12

Studies on HLA Associations show that in a North American Population IgE and IgG hypersensitivity to the ragweed Ags is associated with ____ in patients with ragweed pollen allergy 

HLA-DR2

13

CD14

  • Main cellular expression:
    • Dendritic cells
    • Monocytes
    • Macrophages
    • Granulocytes
  • Known or proposed function(s)
    • Binds complex of LPS and LPS-binding protein and Displays LPS to TLR4; required for LPS-induced macrophage activation 

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High levels of ___ in the cord blood of infants predicts future development of atopy

IgE 

15

What is the hygiene hypothesis

  • the increased incidence of allergy is associated with the decrease in exposure to common infections during early life 
  • infections in childhoood cause Th1-type  responses and restore the Th1/Th2 balance
  • Increased hygiene leads to:
    • Shift form Th1 to Th2 type of immunity
    • Decreased number/activity of Treg cells

16

Th2 type cells produce IL-4 and IL-13 that function to

  • IL-4 
    • B cells:
      • Isotype switching ot IgE
    • T cells:
      • Th2 differentiation, proliferation
    • Macrophages:
      • Alternative activation and inhibition of IFN-gamma-mediated classical activation 
    • Mast cells: proliferation
  • IL-13
    • B cells:
      • Isotype switching to IgE
    • Epithelial cells:
      • Increased mucus produciton 
    • Fibroblasts:
      • increased collagen synthesis 
    • Macrophages:
      • Alternative activation 

17

Crosslinking of FceRI leads to 

activation of the cells (mast cells, basophils) and release of inflammatory mediators 

18

Mast cells reside in the ___ 

tissue (usually near a blood vessel)

19

Basophils reside in 

circulation 

20

Explain desensitization by allergen immunotherapy 

  • It compreses an induction of subcutaneous injections of increasing doses of the allergen extract, given once every 1-2 weeks 
  • Once the maximum dose is achieved (usualy after 6-10 weeks), maintenance injections may be required monthly for 2-3 years but may provide benefit for a further number of years 

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