LEC 17 Hypersensitivity Flashcards
1
Q
How does prior sensitization occur in Type I hypersensitivity?
A
- pt exposed to antigen/allergen
- DCs present the antigen/allergen to a Th2 cell
- Th2 cells activated B cells which promotes IgE production
- IgE Fc region binds the Fc receptor of a mast cell
- pt is now said to be sensitized
2
Q
What antibody class is most important in type I hypersensitivity?
A
IgE
3
Q
What is the mechanism by which a type I hypersensitivity occurs?
A
- antigen binds and cross-links a prebound IgE on a mast cell, basophil, or activated eosinophil
- Mast cell degranulation and release of histamine, proteases
4
Q
How quickly does a type I hypersensitivity reaction occur?
A
minutes to hours
5
Q
The released inflammatory mediators from degranulation of the mast cell during a type I hypersensitivity reaction induce what effects on the body?
A
- vascular permeability (Swelling/edema)
- vasodilation (Low BP)
- bronchial and visceral smooth muscle contraction (bronchospasm/wheezing)
- mucus secretions in nasal, bronchial, and gastric glands
- local inflammation
6
Q
Which eicosanoids do mast cells produce during a type I hypersensitivity reaction?
A
Prostaglandins and Leukotrienes
LTs are potent bronchial constrictors & increase vascular permeability
7
Q
Hours after mast cell activation in a type I hypersensitivity reaction, what cytokines are produced by the mast cell?
A
- IL-4
- IL-5
- IL-13
- TGF-β
