Allergy Flashcards
What indicates the presence of an allergy?
- Allergen-specific IgE presence
- Mast cell/eosiniphil recruitment
- Th2 resposne with IL-4,5,13
What is atopy?
Likelihood of developing a hypersensitivity reaction to common allergens
What is the chemical structure of most allergens?
Protein or glycoproteins
How do allergens activate the innate immune system?
- Enzymatic activity
2. Activating PRR
Allergic rhinitis is more commonly found with what?
Outdoor allergens
The protease activity of allergens lends them what benefit?
Ability to cross the skin or mucosal barrier
What factor would contribute to the over development of Th2 which would make a person more susceptible to develop allergies?
- Antibiotic use
- Urban life
- Diet
- Sensitization to house-dust, mites, bugs
What gene polymorphism same considered to contribute to the formation of allergic disease?
- High Fcepsilon beta chain receptor
- IL-4 gene (upregulated)
- HLA-DR
- CD14
What can contribute to reducing the development of atopic phenotypes (Type I hypersensitivity reaction)?
Increasing development of Th1 cells will help increase the Treg cells produced early in life. Furthermore, reduce the Th2 cells that are produced early in life, reducing ability for Type I reactions
What factors help contribute to Th1 stimulation and therefore reducing the overpopulation of Th2 cells?
- Rural life
- Siblings
- Helminth infections
- LPS exposure
- Exposure to multiple antigens
Allergens are proteins or glycoproteins meaning they will interact with what cells for presentation?
- APC for MHCII presentation which causes release of IL-4 from the DC, causing differentiation of T cell into Th2
What is the effect of histamine release?
Smooth muscle contraction, vascular permeability
What is the effect of TNF-alpha and IL-1
target to endothelial cells, causing inflammation
What is the effect of tryptase?
Causes anaphylaxis and urticaria
What is the effect of prostaglandin E2 (PGE2)?
Cause pain and increase vascular permeability
What is the effect of PGD2 and leukotrienes?
Smooth muscle contraction and vascular permeability
What is the effect of bradykinin?
Vasodilation, which can cause hypotension
What are the different mechanisms for desensitization?
- IgG blocking antibodies
- Regulation
- Immune deviation
How does IgG blocking antibodies promote a mechanism of desensitization?
IgG4 will continue to develop and compete for allergen binding with IgE. Reducing the ability for IgE to bind with Fc(epsilon)RI and cause de granulation of mast cells.
How does regulation of mechanisms of desensitization essentially reduce allergen sensitivity?
This will increase the number of T red cells which can more effectively reduce migration/infiltration/inflammation of the other cell types
How can immune deviation contribute to the desensitization mechanism for type I hypersensitivity reactions?
Reduce Th2 and increase Th1. Th1 are inhibitory to Th2 formation, which will reduce IgE production and therefore the ability for mast cells to bind and become de granulated.
What is an allergen?
Ag that stimulates allergic reaction with little or no intrinsic activity
