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17 Cards in this Set
- Front
- Back
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What are the 4 subdivision of hypersensitivity disorders?
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• Type I: Immediate hypersensitivity disorder
• Type II: antibody-mediated disorders • Type III: immune complex-mediated disorders • Type IV: T-cell-mediated disorders |
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What is the mechanism of type I hypersensitivity disorders?
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IgE-mediated hypersensitivity that leads to the release of inflammatory mediators for sensitized mast cells
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Name and describe the 2 phases of type I hypersensitivity reactions
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1. Primary early response: characterized by vasodilation, vascular leakage, and smooth muscle contraction
2. Secondary or late phase response: chaharcterized by more intense infiltration of tissues w/ eosinophils & epithelial cell damage |
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What is an anaphylactic reaction?
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• a systemic life-threatening hypersensitivity reaction
• characterized by edema in many tissues and a fall in BP secondary to vasodilation |
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What is an atopic reaction?
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• a type I reaction when the antigen is confined to a particular site
• refers to a genetically determined hypersensitivity to common environmental allergens |
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What are some common atopic disorders?
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• urticaria (hives)
• allergic rhinitis (hay fever) • atopic dermatitis • food allergies • some forms of asthma |
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What are characteristics of type II hypersensitivity reactions?
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• mediated by IgG or IgM antibodies directed againsts antigens on the surface of cells
• examples include mismatched blood transfusion rxns, ABO or Rh incompatibility, and certain drug reactions |
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What are characteristics of type III hypersensitivity reactions?
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• mediated by the formation of insoluble antigen-antibody complexes that activate complement
• generates chemotactic and vasoactive mediates that cause tissue damage by alering blood flow, increasing vascular permability, and inducing an inflammatory response |
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What are examples of type III hypersensitivity reactions?
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• Post-streptococcal glomerulonephritis
• Osler nodes of endocarditis |
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What type of hypersensitivity reaction involve T-cell mediated immune responses?
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Type IV
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What are the 2 basic types of type IV hypersensitivity reactions?
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• direct cell-mediated cytotoxicity
• delayed-type hypersensitivity disorders |
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Describe direct cell-mediated cytotoxicity
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• CD8+ cytolytic T lymphocytes (CTLs) directly kill the antigen-presenting target cells
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Describe delayed-type hypersensitivity reactions
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cytokines promote differentiation & activation of macrophages that function as phagocytic and antigen-presenting cells
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What are examples of a type IV delayed-type hypersensitivity reaction?
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• Purified protein derivative (PPD)
• Allergic contact dermatitis • Hypersensitivity Pneumonitis |
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What is the most common type of allergic reaction to latex?
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a contact dermatitis caused by a type IV delay-type hypersensitivity
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What is self-tolerance?
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the ability of the immune system to differentiate self from non-self
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what causes B-cells to produce IgE?
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stimulation by an antigen-stimulated T-H2 cell
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