Hypersensitivity and Allergy Flashcards
(20 cards)
What is Type 1 Hypersensitivity?
Allergy (environmental non-infectious antigens)
What is the time period for the immediate reaction in Type 1 hypersensitivity?
Less than 30 minutes
What is the Sensitisation in Type 1 Hypersensitivity?
First encounter with the antigen resulting in activation of APC and Memory effector cells
What is are the overlying mechanism involved in Type 1 Hypersensitivity?
- Adaptive response
- Mast cell activation
What is involved in the adaptive response of Type 1 Hypersensitivity?
- Abnormal TH2 Cell Response
- IgE production
Where are Mast Cell found?
- Mucosal tissue
- Epithelial tissue
- Connective Tissue surrounding blood vessels
What happens in the second exposure to the allergen?
Allergen-IgE cross linking occurs.
This leads to Mast Cell Degranulation
What happens in the first exposure response?
TH2 response leading to
- Activation of APC
- Memory Effector Cells
What are the mediators release as a result of Mast Cell activation?
- Histamine
- Leukotriene C4, D4, E4
- Tryptase
- Platelet Activating Factor
What causes Uriticaria?
Mast cell activation in Epidermis
Release of
- Histamine
- Leukotrienes
What can Urticaria lead to if there is prolonged and chronic exposure to allergen?
- Atopic Dermatitis
- Eczema
What causes Angioedema?
Mast Cell Activation in Deep Dermis
Release of
- Histamine
- Bradykinin
Where does Angioedema affect?
- Lip
- Eyes
- Tongue
- Upper Respiratory Airways
What is used to give symptomatic relief of Allergy?
Anti-histamines
Corticosteroids
Leukotriene Receptor Antagonists
How is Desensitization therapy administered to patients?
- Anti-IgE monoclonal antibody
- Oral immunotherapy targeting: Shift from TH2 to TH1, Inhibitory anti-inflammatory cytokines, CD4+CD25 Regulatory T cells, Allergen specific blocking IgG
What are the type of allergens?
-Seasonal Exposure
Tree and Grass Pollens
-Perennial Exposure
House Mite, Animal Dander, Fungal Spores
-Accidental Exposure
Insect Venom, Medicine, Latex, Foods (milk, peanuts, nuts)
What is the Hygiene Hypothesis?
Children exposed to animals, Pets, Microbes, in the early postnatal period appear to be protected against certain allergic diseases
What is the Biodiversity Hypothesis?
Western lifestyle induces alteration of the symbiotic relationships with parasites and bacteria leading to dysbiosis of microbiome at mucosal surfaces.
What is dysbiosis?
What is microbiome?
- Compositional and functional alterations in microbiome
- Complete genetic content of all the microorganisms that typically inhabit the body such as the skin or gastrointestinal tract
What are the Types of Hypersensitivity?
Type 1: Allergy (environmental non-infectious antigens)
Type 2: Cell Bound antigen
Type 3: Immune Complexes
Type 4: Involves lymphocytes and macrophages
