Hypersensitivity Flashcards
Hypersensetivity
undesirable pathologic lesions triggered by immune responses
Hypersensitivity Types
Type I, Type II, Type III, Type IV
Parasitic Infestation in normal animal
inflammatory responses that result from the release of the contents of the mast cell, basophil, and eosinophil cytoplasmic granules.
Response in Hypersensitive animal
causes unwanted inflammatory diseases. Inflammatory mediators, cytokines, and enzymes are rapidly released from mast cell granules. These cause allergies and anaphylaxis
First Exposure to Allergen
hypersensitive animal responds to allergen by mounting an exaggerated Th2 response and so produce excessive IgE. IgE will bind to tissue mast cells
Second Exposure to Allergen
degranulation is initiated when an antigen molecule cross-links IgE to two Fc Receptors
Mast Cell Degranulation
- very rapid (seconds to minutes). Granules are extruded from the cell and then their contents can diffuse into tissues.
- Mast cells begin to generate leukotrienes and prostaglandins
- This is followed by activation of cytokine genes and cytokine synthesis (IL-4, IL-5, and IL-13)
Allergy effects
histamine, prostaglandins, and leukotrienes cause vasodilation, vascular leak, and bronchial constriction
Anaphylaxis
- A sudden shock syndrome resulting from the massive release of mast cell mediators
- Histamine cause massive smooth muscle contraction
- The bronchi constrict and the victim suffocates
Allergy Diagnosis
panel of intradermal skin tests. Each spot denotes a position where a small volume of dilute allergen was injected intradermally. If the dog is allergic to an allergen, a local reaction characterized by redness and swelling occur around the injection site.
Immunotherapy
- Trying to force a switch from IgE to IgG
2. Administer very low doses of antigen. Gradually increase the dose.