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AllergicRhinitis Jax
Allergic Rhinitis, Jackson, 1/23/2013
| Question | Answer |
|---|---|
| Define atopy | IgE mediated immediate hypersensitivity reaction to certain antigens causing rapid vascular leakage, and mucosal secretions, followed by inflammation |
| Define immediate hypersensitivity | Vascular and smooth muscles reactions that happen within minutes of reintroduction of antigen to previously sensitized individuals |
| Define late-phase hypersensitivity | Mast cell mediators that are cytokines recruit neutrophils and eosinophils to the site of reaction over several hours; Result of tissue injury from repeated bouts of immediate hypersensitivity |
| Define allergen | Antigens that elicit immediate hypersensitivity reactions; any atopic individual can be allergic to one or more antigen |
| Which cell mediators cause rapid increases in vascular permeability and smooth muscle contractions, causing many symptoms of allergy? | Mast cells |
| Antigens bind to B cells which activate | B and T cells in an immune response |
| In response to an allergen, Th2 cells stimulate the production of | IgE |
| IgE binds to what? | Fc receptor on mast cells |
| List the Ig in order of most concentrated to least concentrated in the human body | IgG, IgA, IgM, IgD, IgE |
| Describe a type 1 allergic reaction | Allergen reacts with Th2 cells instead of Th1 cells to produce IgE. IgE binds to the Fc receptors on mast cells and basophils which causes degranulation |
| A high IgE level is caused by | A Th2 helper t cell response |
| Which cytokines are important for the increase of IgE and increased mucus production | IL4 and IL13 |
| What test is used to measure allergen-specific IgE | Immunoassay |
| What does IL4 do? | Stimulates B lymphocytes for the allergen to switch to IgE producing plasma cells |
| In atopic patients, mast cells are coated with IgE antibodies specific for the antigen they are allergic to. This coating of mast cells leads to | Sensitization because immune response will be elicited each time the person is exposed to the allergen |
| Binding of IgE activates mechanical signalling from mast cells causing signal trasduction to what three pathways | Degranulation, Synthesis and secretion of lipid mediators, and synthesis and secretion of cytokines |
| Define degranulation | Granule exocytosis leads to vasoactive amines to cause vascular dilation and smooth muscle contraction and proteases to lead to local tissue damage |
| What do lipid mediators do? | Causes prostaglandins to stimulate vascular dilation and leukotrienes to cause prolonged smooth muscle contractions |
| What do cytokines do? | Local inflammation (leukocyte recruitment) and cause the late phase reaction |
| Explain the pathogenesis of allergic rhinitis | Nasal mucosa react to an inhaled allergen by producing histamine and Th2 cells that produce IL-13 (increased mucus production) |
| Most skin tests for allergies are rapid, sensitive, and cost effective tests for | Allergen-specific IgE on the patients mast cells |
| Positive skin test gives what reaction? | Wheal and flare |
| The wheal and flare reaction is due mainly to | Histamine |
| Which reaction is read for a allergen test? | Early phase |
| Describe an in vitro allergen test | Blood is taken to measure blood IgE levels. Total blood IgE is measured and then allergen-specific IgE is measured using an ELISA or fluorescent enzyme |
| Why would you use an in vitro test instead of a skin test? | There is no risk for allergic reactions and it is not affected my any medications the patient may be taking |
Created by:
mcasto
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