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19 Cards in this Set
- Front
- Back
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What type of Ab mediates type I hypersensitivites?
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IgE
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How quickly do type I hyp. occur?
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Within minutes
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Allergy response is driven by what type of T cell?
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Th2
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True or false: Th2 cells can switch the B cell Ab isotype from IgM to IgE?
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True
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Antigens that selectively stimulate Th2 cells that drive IgE responses are called?
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Allergens
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Why does transmucosal Ag delivery favor Th2 activation over Th1?
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Because IFN-gamma secreting Th1 cells can inhibit IgE production.
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Where are mast cells located?
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Tissues near small blood vessels and postcapillary venules
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What causes mast cells to release histimine?
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When Ag crosslinks with IgE bound to the FceRI receptor on the surface of the mast cell.
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What three things do mast cells release?
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Histamine, Enzymes that break down tissue matrix proteins and other inflammatory molecules such as TNF-alpha and IL-4.
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What are the main steps that occur in sensitizing an individual for an allergic response?
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Ag is taken up by APC and complexed with MHC II. APC presents AG to naive T cells, promoting Th2 idfferentiation. Th2 cell secretes cytokines causing B cells to become IgE plasma cells. Clones of the plasma cells and memory cells are made. IgE binds mast cell receptors, sensitizing the individual.
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What happens in second exposure in an allergic response?
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Cross-linking of cell-bound IgE by Ag causes mast cell degranulation. Histamine and others are released. These mediators cause symptoms common of many allergies such as asthma, hay fever, etc.
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What happens in allergic rhinitis?
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Inhilation of Ag activates mucosal mast cells under nasal epithelium. Local edema leads to sneeizing etc from histamine release.
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What can occur when airborne allergens deposit on the cojunctiva of the eye?
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Allergic conjunctivitis.
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What would occur to a person who is allergic to bee stings?
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Local mast cell activation immediately causes increased vascular permeability, vasodilation and fluid leakage.
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A more prolonged skin allergy that causes rash from chronic inflammation is called what?
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Eczema
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What allergic response occurs commonly from ingested allergens?
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Urticaria "Hives"
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What can occur when allergen is given systemically or rapidly absorbed from the gut?
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Anaphylactic shock.
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Why is anaphylactic shock such a rapid and fatal response?
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Mast cells associated with all blood vessels may become activated leading to loss of BP, constricted airways, or epiglottal swelling.
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Rapid injection of what can prevent fatalities in anaphylactic shock?
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Epinephrin
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