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23 Cards in this Set
- Front
- Back
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Which of the hypersensitivity reactions are antibody mediated?
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Types 1, 11, and 111.
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Which of the hypersensitivity reactions is cell mediated?
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Type 1V
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What antibody mediates type 1 reactions?
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Immunoglobulin E(IgE)
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What antibodies mediate types 11 and 111 reactions?
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IgG and IgM
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What are type 1 reactions also referred to as?
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Immediate hypersensitivity or anaphylactic hypersensitivity
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In type 1 reactions, allergens(antigens) are presented to TH2 cells. Theactivated TH2 cells then release IL-4, IL-5 and IL-13. Describe the function of each of these cytokines in type 1 reactions.
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IL-4- key factor that causes B cells to switch from IgM to IgE production
IL-5 activates eosinophils IL-13- also promotes IgE production and causes mucus secretion. |
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What are the steps of a type 1 reaction?
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IgE antibody is induced by an allergen---IgE binds to Fc receptors on the surface of mast cells/basophils. When the individual is reexposed to the allergen the second time---the allergen causes cross linking of bound IgE molecules---the cross linking activates IgE mediated degranulation in mast cells/basophils with release of various mediators.
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Histamine and proteases/hydrolases are primary mediators. What are their functions?
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Histamine: vasodilation, increases vascular permeability, increases secretions(nasal respiratory).
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The function of proteases/hydrolases: tissue damage, activate complement. TRUE/FALSE
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TRUE
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Leukotrienes B4, C4, D4, E4, and cytokines are secondary mediators. What are their functions?
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Leukotrienes: B4--- recruits WBC. C4/D4/E4---vasodilation, increases vascular permeability.
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Cytokines: mediate the inflammatory response of the late phase. TRUE/FALSE
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TRUE
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What are the phases of type 1 hypersensitivity reactions?
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Immediate phase: rapid degranulation of preformed mediators in mast cells/basophils within minutes of reexposure to antigen that cross links the cell bound-IgE.
Late phase: 2-24 hrs after antigen exposure, secondary mediators cause an influx of inflammatory cells. |
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What are the symptoms of the immediate phase of type 1 reactions?
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Edema, erythema, itching, wheal and flare.
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What are the symptoms of the late phase of type 1 reactions?
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Edema and induration(firmness due to increased tissue density).
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What are the common clinical manisfestations of type 1 hypersensitivity reactions?
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Skin: urticaria(hives), eczema
Airways: rhinitis, asthma Eyes: conjunctivitis |
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What are the consequences of IgE mediated responses in the GI tract, airways, and blood vessels?
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GI tract: increased fluid secretion, increased peristalsis---expulsion of GI tract contents(diarrhea, vomiting).
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What are the consequences of IgE mediated responses in the airways and blood vessels?
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Airways: decreased diameter, increased mucus secretion---expulsion of contents(phlegm and coughing)
Blood vessels: increased blood flow, increased permeability---edema, inflammation, and increased lymph flow takes antigen to lymph nodes. |
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What is the most severe form of type 1 hypersensitivity reactions?
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Systemic anaphylaxis, which manifests as life threatening bronchoconstriction and systemic vasodilation(hypotensive shock)
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What are some common causes of anaphylaxis?
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Peanuts, bee venom, medicine and latex
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What drugs are commonly given to prevent anaphylactic reactions?
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Antihistamines, corticosteroids and cromolyn sodium. Epinephrine can be given as treatment for anaphylactic reactions.
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How does cromolyn sodium work on mast cells?
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It stabilizes mast cell membranes preventing degranulation.
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What do patients with atopic disorders(asthma, eczema, and urticaria) have elevated levels of?
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IgE
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Drugs commonly cause hypersensitivity reactions by acting as haptens. What is a hapten and how does this induce hypersensitivity reactions?
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A hapten is a molecule, which by itself, cannot induce an immune response. The hapten, usually a drug or its metabolitr binds to an endogenous protein that then induces antibody formation. The antibody reacts to the hapten(drug or its metabolite)upon subsequent exposure.
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