Type I Hypersensitivity- lecture 10/26/21 Flashcards
Type I hypersensitivity mediated by:
IgE, mast cell degranulation
Immediate mast cell mediators
Histamine, IL-8, ECF-A
Mast cell mediators after ~30-60 mins
Prostaglandins, leukotrienes
Histamine
Itching, edema (opens blood vessels), bronchial constriction
ECF-A
Eosinophil chemotactic factor
Il-8
Chemokine, neutrophil chemotaxis
Leukotrienes and prostaglandins (4 functions)
- Edema
- Bronchial constriction
- Eosinophil activation
- Eosinophil and neutrophil chemotaxis
Sensitization
Making antibodies (IgE) for a particular antigen (allergen), could take a number of exposures
Factors of why individuals make IgE antibodies
- Genetic component
- Environmental component
- Mode of at administration (skin or mucosal membrane)
- APCs preferentially activating Th2 and Tfh secreting IL-4 and IL-13
- Failure to control Th2
Anaphylactic shock
Blood pressure drop caused by systemic vasodilation
Examples of IgE mediated allergic reaction
- Allergic rhinitis
- bronchial asthma
- Acute drug reactions
- Food allergies
- Insect stings
- acute urticaria
Two phases of allergic response
Acute phase and late phase (chemokine from cells recruited to the area and those cells
Treatments of type I hypersensitivity (5)
- Epinephrine
- Removal of antigen
- Treat with antihistamines etc
- Treat chronic inflammation with corticosteroids
- Xolair (inhibits IgE binding to mast cells)